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Road traffic pollution and public nuisance
the Science of the Total Environment The Science of the Total Environment 146/147 (1994~ 81-91
ELSEVIER
Road traffic pollution and public nuisance I.S. M c C r a e
~a
, I.D. Williams b
aTransport Research Laboratory, Old Wokingham Road, Crowthorne, Berkshire, RGll 6A U, UK bUrban Pollution Research Centre, School of Environmental Science and Engineering, Middlesex University. Bounds Green Road. London, NIl 2NQ, UK
Abstract Road traffic affects the public in a wide variety of ways, many of which cause some degree of annoyance. The major disturbances to the public arising from vehicular emissions include physical effects such as the irritation of eyes and mucous membranes, visual intrusion, soiling, or more subjective impacts. A literature survey has been conducted which identified the vehicle-derived air pollutants suspected of causing some degree of nuisance to the public but also highlighted the limited data in this area. A preliminary investigation of the relationship between public attitude and pollutant concentrations has been conducted at two locations in the London Borough of Ealing and a single location in the London Borough of Haringey. A range of pollutants was monitored continuously including oxides of carbon, nitrogen and sulphur, selected volatile organic compounds and particulate matter. Traffic flows and meteorological conditions were also recorded throughout the survey period. To measure the local public opinion concerning vehiclederived pollutants, pedestrians and occupants of residential and business premises were surveyed. The preliminary analysis of this data indicates the importance of diesel-engined vehicles to public annoyance and the significance of diesel derived particulate matter. Key words: Motor vehicle emissions; Particulates; Public nuisance; Social surveys
1. Introduction Air pollution from traffic is one of the main factors considered in the environmental appraisal of road schemes. At present this appraisal concentrates on the emission and roadside concentration of those regulated compounds which are recognised as causing adverse effects on human health or the local or regional environment. The prominence of the motor vehicle as a source of pollution, combined with the greater environmental awareness of * Corresponding author.
the European public, has led to an increased concern towards vehicle-derived pollutants that cause, or are suspected to cause, nuisance to the general public. Previous research [1-3] has indicated that disturbances to the public from vehicle emissions may include dust and dirt; smoke, fumes and odour; reduced visibility; urban soiling; and physical effects such as irritation of the eyes and mucous membranes. The majority of this research has concentrated on social survey techniques and only limited attempts have been made to link the degree of public nuisance (as measured through social survey techniques) to actual measured levels of
0048-9697/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved. SSDI 0048-9697(92)03593-Q
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Table 1 Vehicle derived pollutants contributing to nuisance effects Nuisance
Pollutant
Fumes/smoke/odour Visibility reduction Soiling Physical irritation
Particulates/Volatile organic compounds (e.g. carbonyl compounds)/Hydrocarbons Particulates/Hydrocarbons/Secondary pollutants (e.g. ozone, nitrogen dioxide)/Hydrocarbons Particulates Particulates/Hydrocarbons/Secondary pollutants/Volatile organic compounds
pollutants [4,5]. Those air pollutants identified as contributors to nuisance effects are indicated in Table 1. The aim of this research is to relate the subjective nuisance from motor vehicle emissions to some quantifiable parameter such as traffic flow or an easily monitored pollutant such as carbon monoxide, which itself does not necessarily cause nuisance at the concentrations that occur in practice. This paper describes the preliminary analysis of the results from a series of experiments to quantify the nuisance effects reported by the public to air pollutants from road traffic.
2. Experimental methods A pilot survey was performed initially at two sites in the London Borough of Ealing with the first of a series of planned follow-up surveys conducted in Wood Green, in the London Borough of Haringey. A residential and a commercial site were selected in the Ealing area, with a single residential site chosen in the Wood Green vicinity. Ealing is a fairly affluent district in west London, with a central commercial sector and large residential estates to the north and south of the main highway. It is an extremely busy commuter area, with rail and underground links to central London and ready access to the motorway network. Wood Green is a less prosperous, but equally busy, area in north London, with a popular central shopping area largely surrounded by terraced housing. It is situated to the south of the busy North Circular Road and also has rail and underground links with central London. The pilot survey residential site (Site A) was located to the north-east of Ealing town centre in Westbury Road, an area containing mainly private
detached and semi-detached housing and some multi-storey apartments. Continuous air quality monitoring was performed at this site between March and May 1991, and was accompanied by the household social survey. The commercial site for the pilot survey (Site B) was located in Ealing High Street, which is a busy one-way street in the centre of the town. The street contains a number of shops and offices, the central post office, one of the main entrances to a popular shopping complex and several bus stops. Continuous air quality monitoring was carried out at this site, between the end of May to the beginning of July 1991. Social surveys were conducted throughout the town centre between February and July 1991. The Wood Green residential site was situated to the east of the town centre, in Vincent Road (Site C), where continuous air quality monitoring was undertaken between February and April 1992. The housing in the area consists mainly of small terraced residences, some of which have been converted into apartments. Social surveys were performed in this area between February and March 1992. 2.1. Social survey methods
During the pilot survey, three distinct categories of respondent were targeted: pedestrians, householders and business people, where business people were defined as those people who work in offices or shops in the survey areas. Specific questionnaires were designed for each target group to take into account factors such as the interview location, the (assumed) special interests of each group and the time available for the interview. Pedestrians and householders were interviewed individually, but it became apparent as the survey progressed that the majority of business people did not have sufficient free time available for a lengthy
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interview. Therefore, a self-completion postal questionnaire was designed specifically for businesses in an attempt to improve the response rate. In order to allow the responses of the different target groups to be compared, each questionnaire contained a number of common questions. The interviewees' responses were coded to allow the data to be stored, retrieved and analysed by computer. The questions were specifically designed to: •
• •
assess the relative importance to the public of air pollution from road traffic when compared to other social and environmental issues; identify the environmental nuisances which are believed to be traffic generated; discover the extent of the various nuisances to the public at work, at home and outdoors in urban areas.
Classification data, such as gender, age, and socio-economic grouping, were also collected so that the responses of specific groups to a particular question or set of questions could be compared. A detailed description of the questionnaires used in this pilot survey will be available shortly [6]. When the pilot survey was completed, the methodology utilised was evaluated, resulting in the social survey techniques being improved and modified. The updated methodology was used in the third survey at Wood Green, although to date only householders have been surveyed.
2.2. Air quality monitoring
Air quality parameters were monitored using T R L ' s mobile laboratory [7]. The laboratory is equipped to monitor carbon monoxide, ozone, nitrogen oxides (nitric oxide, nitrogen dioxide and total), sulphur dioxide, gaseous hydrocarbons (methane, non-methane and total) and total suspended particulates. Gaseous samples were collected via a PTFE lined manifold, set 1.6 m above ground level, through which ambient air was continuously drawn. Gaseous pollutants were detected using rack-mounted commercially available analysers and pollutant concentrations were recorded on a data logger. Readings were logged once every second and 15-rain averages were calculated and stored on disc for later analysis. Total suspended particulates (TSP) were collected, at a height of 2.5 m, by drawing ambient air through 60-mm diameter glass fibre filter papers, using two different flow rates. Twenty-four-hour samples were collected using a sampling pump with a flow rate of 30 l/min, and 4-h samples spanning the morning and evening peak traffic volumes were collected using flow rates of approximately 90 l/rain, The mobile laboratory was also modified to monitor smoke and carbonyl compounds, which were regarded as potentially important contributors to nuisance effects [3,6]. Smoke was monitored using the British Standard 8-port smoke sampler and carbonyls were measured using US Environmental Protection Agency Method T O - 5 , both with a sample intake height of 1.6 m [81.
Table 2 Pollutants monitored in TRL's mobile laboratory Pollutant
Detection Principle
Sampling Period
Carbon monoxide Nitrogen oxides Gaseous hydrocarbons Ozone Sulphur dioxide Total suspended particulates
Infra-red {Gas correlation) Chemiluminescence Flame ionisation Ultra-violet absorption Ultra-violet fluorescence Gravimetric
Smoke Carbonyl compounds
Reflectance HPLC with UV/visible detector
Continuous Continuous Continuous Continuous Continuous 24 h 4 h (peak traffic times) 24 h 2-3 h {peak traffic times)
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3. Results 3.1 Social survey results
A total of 209 pedestrians, 42 business people and 44 householders were interviewed during the pilot survey and 35 householders were interviewed at Wood Green. The classification data collected showed that the sample population was broadly representative of the Ealing community when compared with the 1981 National Census data for Ealing, with women being statistically slightly over-represented in the business and household surveys, and slightly under-represented in the pedestrian survey. The pilot questionnaire was designed so that the first question assessed the public's concern about their local environment compared to other issues that may worry them. This enabled concern generated by nuisance effects to be put into perspective. The question listed ten major social issues: health/social services, law and order, education, unemployment, local environment, rising prices, global environment, housing, rising population and old age pensions, and respondents were asked to name the three issues which were the most important to them. The local environment ranked fifth for business and household respondents and seventh for pedestrians. It was felt that simply ranking the issues in order of priority did not provide information about the magnitude of concern felt by the public about these issues, and so the question was modified for the Wood Green survey to take this into account. An eleventh category, 'air pollution from road traffic', was also added to the above list. Thirty-seven percent of the Wood Green household respondents were 'very' or
Table 3 Response to the pilot survey question, 'when you are inside (the shop/your home) can you please tell me if you are ever bothered or disturbed by any of these effects?' Effect
% Bothered or disturbed
Smoke, fumes or odour Noise Dust and dirt on the inside of the (shop windows/curtains or inside window sills) Dust and dirt on (shelves or goods/furniture or walls) Vibrations
Business
Household
71 86
25 63
88
63
86
44
52
50
'extremely' worried about their local environment and over 70% were 'very' or 'extremely' worried about air pollution from road traffic (a figure exceeded only by rising prices). The second pilot survey question was specifically designed to prioritise local environmental issues by asking respondents to choose the three issues (from a list of ten) which caused them the greatest nuisance when they were out walking in Ealing. For each target group the three greatest nuisances were, litter and rubbish; the amount of road traffic; and smoke, fumes or odour from road traffic. Noise from road traffic came either fourth or fifth, with dust and dirt (generally, not specifically generated by traffic) placed sixth. This question was also modified for the Wood Green householder survey to take into account the magnitude of the respondents' concern. The results for the
Table 4 Response by householders in Wood Green to the question 'Inside your h o m e . . , how often are you bothered or disturbed by the following effects?' Effect
Smoke, fumes and odour from road traffic Noise from road traffic Vibrations from road traffic Dust and dirt from road traffic
Never (%)
Occasionally
Frequently
All the time
(%)
(%)
(%,)
46
34
17
3
20 23 32
37 34 32
29 26 20
14 17 17
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Wood Green site were very similar to those for the pilot survey. The data collected also shows that over 50% of the household respondents were 'very' or 'extremely' bothered by smoke, fumes and odour and the amount of road traffic, and that 45% were similarly bothered by dust and dirt. More detailed questions, designed to establish the specific environmental problems and health effects that bother or disturb the public and to discover if the public attributes these problems and effects to vehicular sources, were then directed to each respondent group. The pilot survey results indicated a very high level of indoor disturbance from noise and dust/dirt, as illustrated in Table 3. Householders were also asked what they thought was the main cause of the effects listed in Table 3. Road traffic was blamed by at least 38% of total household respondents for the noise inside their homes, by 36% for the dust/dirt on furniture or indoor walls and by 50% for dust/dirt on the inside of curtains or inside window sills. The data in Table 3 also seems to indicate that considerably more business people than householders were bothered indoors by the listed effects, particularly in the case of smoke, fumes or odour. Many of the business people questioned worked in shops immediately adjacent to the Broadway and High St roads, where traffic was frequently slowmoving or stationary, and this possibly contributed to their higher level of disturbance. There is also the possibility of a methodological effect since business respondents completed their questionnaires themselves. The question did not, however, give any information about the frequency of disturbance and was therefore modified for the follow-up survey, the results of which are shown in Table 4.
Table 5 Responses to the question 'when you are out walking in Ealing, can you please tell me if you are ever bothered or disturbed by any of these effects?' Effect
%bothered or disturbed
Smoke, fumes or odour Dust and dirt Noise Smog Blackening of building walls
Business
Household Pedestrian
93 93 93 24 38
70 67 81 16 42
69 57 6I 21 33
The figures shown in Table 4 indicate that over 40% of the total Wood Green household respondents were bothered either 'frequently' or 'all the time' by traffic-induced noise, vibrations and dust/dirt inside their homes, and that over 50% of respondents were bothered at least occasionally by indoor smoke, fumes and odour from road traffic. The level of outdoor disturbance in Ealing to all three target groups from a range of effects is listed in Table 5. Business people generally show more disturbance than both householders and pedestrians, which is consistent with the figures for indoor disturbance shown in Table 3. It is evident that practically every business respondent and at least 50% of pedestrians and householders are bothered or disturbed by smoke, fumes or odour, dust/dirt and noise when they are out walking in Ealing. Smog and the blackening of building walls disturb less people, although they still affect 20-40% of respondents. Householders at Wood Green were asked a modified version of the same
Table 6 Response to the question 'when you are out walking in Wood Green, how often are you bothered or disturbed by followingeffects?' Effect
Never (%)
Occasionally Frequently (%) ~°/~,)
All the time (%)
Smoke, fumes and odour Dust and dirt Noise Smog Blackening of building walls
I1 6 17 43 54
52 48 40 37 34
26 29 17 14 3
11 17 26 6 9
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Table 7 Pedestrian response to the question 'in Ealing, what do you think is the main cause of your/the... (name effect)?' (Selected responses shown) Health/nuisance effect
A. Pollution from road traffic
B. Pollution from road traffic and other
C. Pollution/air pollution
D. General dust and dirt
E. Sum of A-D
Sore or runny eyes Sneezing Irritated throat Dirt on your clothes Dirt on your skin, nails or hair
12 6 10 28 26
3 5 6 8 10
4 1 4 4 4
5 8 1 6 4
24 20 21 46 44
tify whether they were bothered by a range of health/nuisance effects when they were indoors. The effects included sore or runny eyes, sneezing, an irritated throat, dirt on clothes/skin, nails or hair, an unpleasant taste in the mouth, headaches and difficulty in breathing. Less than 10% of both respondent groups felt that road traffic was to blame for any of the indoor problems listed above. All three target groups were also asked to consider these health/nuisance effects outdoors. The results for business and household respondents were very similar and there was only a slight increase in annoyance when respondents were asked to consider these effects outdoors rather than indoors. While over 25% of the pedestrian respondents felt that pollution from road traffic was responsible for the dirt on their clothes, skin, nails or hair, concern about health-related effects
question, and the results show a similar pattern, as illustrated in Table 6. Respondents were also asked what they thought caused the outdoor effects listed in Tables 5 and 6. In the pilot survey, 50% of the total pedestrian and household respondents thought that pollution from road traffic was primarily responsible for the smoke, fumes or odour and dust/dirt in Ealing, and between 20 and 30% thought that vehiclegenerated pollution was the main cause of the blackening of building walls. In Wood Green, 74% of the total household respondents blamed road traffic pollution primarily for the smoke, fumes and odour, 31% for the dust and dirt, 40% for smog and 29% for the blackening of building walls. The pedestrian, business and household respondents were asked in the pilot survey to iden-
Table 8 Response of Wood Green householders to the question 'when you are (out walking/inside your home) how much are you bothered or disturbed by the following problems?' Effect
Sore or runny eyes Sneezing Dirt on your clothes Dirt on your skin, nails or hair Irritated throat
Not at all or not very bothered (%)
Moderately bothered (%)
Very or extremely bothered (%)
Outdoors
Indoors
Outdoors
Indoors
Outdoors
Indoors
66 66 51 48
89 89 77 74
23 29 32 29
11 11 14 12
I1 5 17 23
0 0 9 14
57
74
20
14
23
12
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was generally lower, with less than 12% of pedestrians blaming these effects exclusively on vehicle-derived pollution. If, however, we make the assumption that all kerbside air pollution and dust/dirt is traffic generated (a 'worst-case scenario'), it is possible to make an estimate of the maximum percentage of people who blame the listed outdoor effects on vehicle-derived air pollution, as shown in Column E of Table 7. Based on this assumption, the results indicate that possibly 45% of pedestrians blame pollution from road traffic for dirt on their clothes, skin, nails or hair, and 1 in 5 feel that road vehicle pollution is responsible for their sore or runny eyes, sneezing and irritated throat when they are outdoors. This question was again modified for the Wood Green householder survey to assess the magnitude of the respondents' concern about each health/ nuisance effect. Some of the effects used in the pilot survey were also dropped from the question, since the public did not appear to be very concerned about them. The results (shown in Table 8) reinforce the findings of the pilot survey that people are mainly concerned about dust/dirt, although in this survey the difference between indoor and outdoor disturbance is more distinct, with approximately 25% more people being disturbed outdoors than indoors. As in the Ealing survey, only a small number of respondents blamed pollution from road traffic exclusively for the effects listed in Table 8, with the 'worst-case scenario' (outlined above) suggesting that possibly 20-30% of
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householders feel that vehicle-derived pollution is responsible for the dirt on their clothes, skin, nails or hair, sneezing and irritated throat. In the pilot survey, all three target groups were asked general questions on air pollution. Between 84 and 93% of people felt that there was air pollution in Ealing, with 84-86% of these respondents choosing exhausts from road traffic (from a list of ten) as one of the three main causes of this pollution. The magnitude of the indoor and outdoor nuisance caused to household respondents by smoke, fumes and odour and dust/dirt from road traffic was measured using a seven-point scale at the Wood Green site. The 'average respondent' appeared to be moderately to very bothered about both of these effects outdoors, with smoke, fumes and odour causing slightly more concern than dust/dirt. Householders were less disturbed indoors than outdoors by these effects, with dust and dirt causing marginally more concern than smoke, fumes and odour. The Wood Green householders were also asked to state specifically what it was about dust/dirt or smoke/fumes/odour that disturbed them. Outdoors, 50% of the total respondents were concerned that smoke and fumes from road traffic would damage their health, while indoors people showed more concern about the actual odours produced by air pollution from road traffic. Approximately 25°/, of the respondents were concerned that the outdoor dust/dirt from road traffic would damage their health and 50% complained that vehicle-generated dust and dirt
Table 9 Pollutant concentrations measured using the TRL mobile laboratory Pollutant
Carbon monoxide Nitric oxide Nitrogen dioxide Methane Non-methane hydrocarbons Sulphur dioxide Ozone
Unit
ppm ppb ppm
ppb
Site C
Site B
Site A Mean
Max
N
Mean
Max
N
Mean
Max
N
1.0 32.5 43.2 1.3 0.5
2.3 126.9 75.7 2.2 1.3
5113 5109 5110 4496 4499
2.8 90.7 61.8 1.2 1.1
7.1 191.8 101.0 1.4 2.9
3829 4251 4251 3693 3693
0.9 19.5 39.2 2.3 0.2
2.3 86.9 68.3 3.0 0.6
4797 4804 4804 44[)2 4464
2.5 15.7
7.5 28.9
4253 5124
9.6
-17.0
4255
6.7 14.7
15.4 24.0
3463 4804
Mean, arithmetic mean; Max, maximum 15-min average, N, number of 15-min periods surveyed.
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Table 10 Smoke concentrations (#g/m3) at the monitored sites Site Ealing Wood Green
Site A Site B Site C
Number of samples
Median
Range
59 39 80
18.0 30.0 16.0
6-42 10-77 7-58
caused indoor soiling to, e.g. walls, doors, windows, and furniture. 3.2 A i r p o l l u t i o n results
The average hourly traffic flow along the roads closest to Sites A, B and C were 470, 462 and 79 vehicles, respectively. Diesel vehicles typically accounted for less than 20% of these flows. The maximum legal speed limit was 30 mph (48 km/h) at each of the sites. A summary of the pollutant concentrations recorded at each of the three sites is indicated in Table 9. The concentrations of all primary pollutants were generally low, which may be explained by the relatively low traffic flows in the immediate vicinity of each site. The concentrations of secondary pollutants (ozone and nitrogen dioxide) were relatively high. This may be explained by the presence of additional sources, other than the local road. Indeed the major thoroughfare, Ealing Broadway, is within half a mile of both Sites A and B and typically has approximately 780 vehicles/h.
A major north-south road passing through Wood Green Shopping City, and carrying a traffic flow of about 1000 vehicles/h, is about 300 m to the west of Site C. At each of the three sites, the weekday traffic flow indicated characteristic morning and evening traffic peaks. A similar distribution was evident during the weekend periods, but with substantially lower traffic flows particularly on Sundays at Sites A and B, although elevated on a Saturday at Site C due to congestion of the main north-south road. Positive and significant correlations were noted between all the primary pollutants and traffic flows at each of the three sites. Smoke and total suspended particulate (TSP) data at all 3 sites are summarised in Tables 10 and 11. The median 24-h smoke and TSP concentrations were higher at the busier commercial site in Ealing (Site B) than at both the residential sites. The 4-h TSP concentrations measured during peak traffic flow were generally higher than the 24-h values, the exception being at site C, where the 24-
Table 11 Total suspended particulate concentrations (/xg/m3) at the monitored sites Site
Sampling period
Numberof samples
Median
Range
Site A
06:00-10:00 16:00-20:00 00:00-24:00 06:00-10:00 16:00-20:00 00:00-24:00 06:00-10:00 16:00-20:00 00:00-24:00
11 12 12 14 16 13 22 23 23
55.2 42.6 35.6 61.2 77.3 45.6 33.2 28.8 29.9
26.9-750.3 a 24.1-1090.8a 21.4-57.7 12.0-105.0 26.1- 146.2 23.2-121.3 15.2-149.9 10.8-131.4 14.3-134.7
Site B Site C
aOn two occasions, extremelyhigh concentrations of TSP were measured extending the data ranges.
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Table 12 Carbonyl compounds (ng/l) at the monitored sites Site
Carbonyl compound
Na
Arithmetic mean
Standard deviation
Range
Site A (17)b
Formaldehyde Acetaldehyde Hexanal Crotonaldehyde Formaldehyde Acetaldehyde Hexanal Crotonaldehyde Formaldehyde Acetaldehyde Hexanal Crotonaldehyde
10 15 12 17 8 9 9 9 33 34 23 36
32.0 5.2 9.2 3.5 29.9 2.9 5.1 1.4 5.0 3.5 3.4 1.5
30.8 5.8 5.3 2.6 36.0 0.6 0.9 0.4 0.5 0.6 0.3 0.1
7.6-116.4 0.9-24.0 3.2-18.2 1.4-11.5 1.7-122.5 1.9-3.9 4.2-6.7 0.7-1.9 0.3-12.9 0.5-20.3 1.7-8.8 0.1-2.9
Site B (9)b
Site C (36)b
aNumber of samples in which compound was detected. bFigures in parentheses refer to the number of samples taken.
h median was similar to the afternoon median. The traffic volumes in both Madeley Road (Site A) and the High Street (Site B) were very similar, although the overall traffic volume in the area surrounding the commercial site was about double that of the residential site. This factor, together with the greater volume of people and the higher percentage of diesel vehicles at the commercial site (11-17%) compared to the residential site (9-10%), probably accounts for the higher levels of smoke and particulates at Site B. The 24-h TSP concentrations are lower than values recorded at other (busier) sites in London [7,9,10]. The ambient carbonyl compound concentrations found during both surveys are summarised in Table 12. The mean values for formaldehyde, acetaldehyde, hexanal and crotonaldehyde were very similar at both the pilot survey locations, although slightly higher at Site A. The mean values found at Wood Green for acetaldehyde, hexanal and crotonaldehyde are similar to those found at Ealing. The formaldehyde value is, however, much lower, but this is probably due to the mean formaldehyde values for both sites at Ealing being strongly influenced by high outlying values. Acrolein, propanal, benzaldehyde and iso-valeraldehyde were not detected at either survey location.
4. Discussion The pilot social survey results indicate that the public are more concerned about social issues such as health/social services, law and order, education and unemployment than issues such as their local environment, which is of medium concern to them. However, traffic related nuisances are important local environmental issues, with 3 of the top 4 local environmental nuisances being vehicle-derived. This was reinforced by the follow-up survey, where over 70% of the household respondents were 'very' or 'extremely' worried about air pollution from road traffic. These results suggest that once people have satisfied their social priorities, environmental (aesthetic) issues become more important, and that road traffic pollution is probably the largest contributor to outdoor public environmental nuisance. The main disturbances to the public from vehicle-derived air pollution are identified as dust/dirt, smoke, fumes or odour and noise. During the business and pedestrian pilot survey period, over 90% of business respondents and 60% of pedestrians complained about outdoor dust/dirt when a median 24-h roadside TSP concentration of 45.6 #g/m 3 was recorded. Indoors, over 80% of
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respondents complained about dust/dirt. Similarly, at least 45-63% of householders complained about indoor dust/dirt when a roadside 24-h median TSP value of 35.6 #g/m 3 was recorded at the Ealing residential site. Road traffic pollution was thought by the respondents to be the main cause of both the indoor and outdoor dust and dirt. At Wood Green, 50% of the total household respondents were disturbed by indoor soiling, considered by them to be caused by vehicle-derived dust/dirt, when a roadside 24-h median TSP value of 29.9 #g/m 3 was recorded. Twenty-five percent of these respondents felt that this dust/dirt damaged their health. The issues of smoke, fumes and odour are more difficult to interpret [3], since the public finds it difficult to decide whether they are disturbed more by visual intrusion (smoke), an unpleasant smell (fumes and odour), a general feeling of discomfort or concerns about health (smoke, fumes and odour). However, the pilot results indicate that 60-90% of the public were disturbed outdoors by smoke, fumes or odour when the mean 24-h smoke concentrations were 18-30 #g/m3 and individual ambient carbonyl compound concentrations ranged from 0.7-123 ng/1. At Wood Green, 90% of household respondents were bothered io some extent by outdoor smoke, fumes and odour when a mean 24-h smoke concentration of 21.9 p,g/m 3 and individual ambient carbonyl concentrations of 0.1-20.3 ng/l were recorded. Inside buildings, 25% of household and 70% of business respondents in Ealing complained about smoke, fumes or odour. Again, road traffic pollution was thought to be the main cause of indoor and outdoor smoke, fumes or odour. The 'worst-case scenario' previously outlined shows that, during the surveys, people generally complained more about dust/dirt than specific health effects when they were out walking, despite the fact that 50% of the Wood Green respondents were worried that traffic-induced smoke and fumes could damage their health. Thus, although people believe that traffic pollution may damage their health, they actually complain more about dust/dirt, and this may indicate that smoke and TSP concentrations are a better indicator of nuisance effects than carbonyl, hydrocarbon or
ozone concentrations. This is in agreement with previous research by Ball and Caswell [11], who suggested that diesel emission standards should be changed from a visibility to a soiling-based criterion, as this is probably a more accurate reflection of the impact that diesel emissions have on the public. Further surveys are planned for 1992, including a commercial site at Wood Green for comparison with the pedestrian and business pilot surveys. The data from all the surveys will eventually be used towards the formulation of a method for the quantification of the nuisance caused to the public by air pollutants generated by road traffic.
5. Acknowledgements The work described in this paper forms part of a Department of Transport funded research programme conducted by the Transport Research Laboratory, and the paper is published by permission of EEA Division and the Chief Executive of TRL. © Crown Copyright 1992. The views expressed in this paper are not necessarily those of the Department of Transport. Extracts from the text may be reproduced, except for commercial purposes, provided the source is acknowledged.
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Price and B. Pepper, Air quality in the vicinity of urban roads. Sci. Total Environ., 93 (1990) 285. 10 M. Lewandowski, J. Booker, B. Jensen and D. Laxen, London Air Pollution Monitoring Network. Third Report, London Scientific Services, LSS/LWMP/89, 1989. 11 D.J. Ball and R. Caswell, Smoke from diesel-engined road vehicles: an investigation into the basis of British and European emission standards. Atmos. Environ., 17(1) (1983) 169.
ELSEVIER
Road traffic pollution and public nuisance I.S. M c C r a e
~a
, I.D. Williams b
aTransport Research Laboratory, Old Wokingham Road, Crowthorne, Berkshire, RGll 6A U, UK bUrban Pollution Research Centre, School of Environmental Science and Engineering, Middlesex University. Bounds Green Road. London, NIl 2NQ, UK
Abstract Road traffic affects the public in a wide variety of ways, many of which cause some degree of annoyance. The major disturbances to the public arising from vehicular emissions include physical effects such as the irritation of eyes and mucous membranes, visual intrusion, soiling, or more subjective impacts. A literature survey has been conducted which identified the vehicle-derived air pollutants suspected of causing some degree of nuisance to the public but also highlighted the limited data in this area. A preliminary investigation of the relationship between public attitude and pollutant concentrations has been conducted at two locations in the London Borough of Ealing and a single location in the London Borough of Haringey. A range of pollutants was monitored continuously including oxides of carbon, nitrogen and sulphur, selected volatile organic compounds and particulate matter. Traffic flows and meteorological conditions were also recorded throughout the survey period. To measure the local public opinion concerning vehiclederived pollutants, pedestrians and occupants of residential and business premises were surveyed. The preliminary analysis of this data indicates the importance of diesel-engined vehicles to public annoyance and the significance of diesel derived particulate matter. Key words: Motor vehicle emissions; Particulates; Public nuisance; Social surveys
1. Introduction Air pollution from traffic is one of the main factors considered in the environmental appraisal of road schemes. At present this appraisal concentrates on the emission and roadside concentration of those regulated compounds which are recognised as causing adverse effects on human health or the local or regional environment. The prominence of the motor vehicle as a source of pollution, combined with the greater environmental awareness of * Corresponding author.
the European public, has led to an increased concern towards vehicle-derived pollutants that cause, or are suspected to cause, nuisance to the general public. Previous research [1-3] has indicated that disturbances to the public from vehicle emissions may include dust and dirt; smoke, fumes and odour; reduced visibility; urban soiling; and physical effects such as irritation of the eyes and mucous membranes. The majority of this research has concentrated on social survey techniques and only limited attempts have been made to link the degree of public nuisance (as measured through social survey techniques) to actual measured levels of
0048-9697/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved. SSDI 0048-9697(92)03593-Q
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Table 1 Vehicle derived pollutants contributing to nuisance effects Nuisance
Pollutant
Fumes/smoke/odour Visibility reduction Soiling Physical irritation
Particulates/Volatile organic compounds (e.g. carbonyl compounds)/Hydrocarbons Particulates/Hydrocarbons/Secondary pollutants (e.g. ozone, nitrogen dioxide)/Hydrocarbons Particulates Particulates/Hydrocarbons/Secondary pollutants/Volatile organic compounds
pollutants [4,5]. Those air pollutants identified as contributors to nuisance effects are indicated in Table 1. The aim of this research is to relate the subjective nuisance from motor vehicle emissions to some quantifiable parameter such as traffic flow or an easily monitored pollutant such as carbon monoxide, which itself does not necessarily cause nuisance at the concentrations that occur in practice. This paper describes the preliminary analysis of the results from a series of experiments to quantify the nuisance effects reported by the public to air pollutants from road traffic.
2. Experimental methods A pilot survey was performed initially at two sites in the London Borough of Ealing with the first of a series of planned follow-up surveys conducted in Wood Green, in the London Borough of Haringey. A residential and a commercial site were selected in the Ealing area, with a single residential site chosen in the Wood Green vicinity. Ealing is a fairly affluent district in west London, with a central commercial sector and large residential estates to the north and south of the main highway. It is an extremely busy commuter area, with rail and underground links to central London and ready access to the motorway network. Wood Green is a less prosperous, but equally busy, area in north London, with a popular central shopping area largely surrounded by terraced housing. It is situated to the south of the busy North Circular Road and also has rail and underground links with central London. The pilot survey residential site (Site A) was located to the north-east of Ealing town centre in Westbury Road, an area containing mainly private
detached and semi-detached housing and some multi-storey apartments. Continuous air quality monitoring was performed at this site between March and May 1991, and was accompanied by the household social survey. The commercial site for the pilot survey (Site B) was located in Ealing High Street, which is a busy one-way street in the centre of the town. The street contains a number of shops and offices, the central post office, one of the main entrances to a popular shopping complex and several bus stops. Continuous air quality monitoring was carried out at this site, between the end of May to the beginning of July 1991. Social surveys were conducted throughout the town centre between February and July 1991. The Wood Green residential site was situated to the east of the town centre, in Vincent Road (Site C), where continuous air quality monitoring was undertaken between February and April 1992. The housing in the area consists mainly of small terraced residences, some of which have been converted into apartments. Social surveys were performed in this area between February and March 1992. 2.1. Social survey methods
During the pilot survey, three distinct categories of respondent were targeted: pedestrians, householders and business people, where business people were defined as those people who work in offices or shops in the survey areas. Specific questionnaires were designed for each target group to take into account factors such as the interview location, the (assumed) special interests of each group and the time available for the interview. Pedestrians and householders were interviewed individually, but it became apparent as the survey progressed that the majority of business people did not have sufficient free time available for a lengthy
83
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interview. Therefore, a self-completion postal questionnaire was designed specifically for businesses in an attempt to improve the response rate. In order to allow the responses of the different target groups to be compared, each questionnaire contained a number of common questions. The interviewees' responses were coded to allow the data to be stored, retrieved and analysed by computer. The questions were specifically designed to: •
• •
assess the relative importance to the public of air pollution from road traffic when compared to other social and environmental issues; identify the environmental nuisances which are believed to be traffic generated; discover the extent of the various nuisances to the public at work, at home and outdoors in urban areas.
Classification data, such as gender, age, and socio-economic grouping, were also collected so that the responses of specific groups to a particular question or set of questions could be compared. A detailed description of the questionnaires used in this pilot survey will be available shortly [6]. When the pilot survey was completed, the methodology utilised was evaluated, resulting in the social survey techniques being improved and modified. The updated methodology was used in the third survey at Wood Green, although to date only householders have been surveyed.
2.2. Air quality monitoring
Air quality parameters were monitored using T R L ' s mobile laboratory [7]. The laboratory is equipped to monitor carbon monoxide, ozone, nitrogen oxides (nitric oxide, nitrogen dioxide and total), sulphur dioxide, gaseous hydrocarbons (methane, non-methane and total) and total suspended particulates. Gaseous samples were collected via a PTFE lined manifold, set 1.6 m above ground level, through which ambient air was continuously drawn. Gaseous pollutants were detected using rack-mounted commercially available analysers and pollutant concentrations were recorded on a data logger. Readings were logged once every second and 15-rain averages were calculated and stored on disc for later analysis. Total suspended particulates (TSP) were collected, at a height of 2.5 m, by drawing ambient air through 60-mm diameter glass fibre filter papers, using two different flow rates. Twenty-four-hour samples were collected using a sampling pump with a flow rate of 30 l/min, and 4-h samples spanning the morning and evening peak traffic volumes were collected using flow rates of approximately 90 l/rain, The mobile laboratory was also modified to monitor smoke and carbonyl compounds, which were regarded as potentially important contributors to nuisance effects [3,6]. Smoke was monitored using the British Standard 8-port smoke sampler and carbonyls were measured using US Environmental Protection Agency Method T O - 5 , both with a sample intake height of 1.6 m [81.
Table 2 Pollutants monitored in TRL's mobile laboratory Pollutant
Detection Principle
Sampling Period
Carbon monoxide Nitrogen oxides Gaseous hydrocarbons Ozone Sulphur dioxide Total suspended particulates
Infra-red {Gas correlation) Chemiluminescence Flame ionisation Ultra-violet absorption Ultra-violet fluorescence Gravimetric
Smoke Carbonyl compounds
Reflectance HPLC with UV/visible detector
Continuous Continuous Continuous Continuous Continuous 24 h 4 h (peak traffic times) 24 h 2-3 h {peak traffic times)
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3. Results 3.1 Social survey results
A total of 209 pedestrians, 42 business people and 44 householders were interviewed during the pilot survey and 35 householders were interviewed at Wood Green. The classification data collected showed that the sample population was broadly representative of the Ealing community when compared with the 1981 National Census data for Ealing, with women being statistically slightly over-represented in the business and household surveys, and slightly under-represented in the pedestrian survey. The pilot questionnaire was designed so that the first question assessed the public's concern about their local environment compared to other issues that may worry them. This enabled concern generated by nuisance effects to be put into perspective. The question listed ten major social issues: health/social services, law and order, education, unemployment, local environment, rising prices, global environment, housing, rising population and old age pensions, and respondents were asked to name the three issues which were the most important to them. The local environment ranked fifth for business and household respondents and seventh for pedestrians. It was felt that simply ranking the issues in order of priority did not provide information about the magnitude of concern felt by the public about these issues, and so the question was modified for the Wood Green survey to take this into account. An eleventh category, 'air pollution from road traffic', was also added to the above list. Thirty-seven percent of the Wood Green household respondents were 'very' or
Table 3 Response to the pilot survey question, 'when you are inside (the shop/your home) can you please tell me if you are ever bothered or disturbed by any of these effects?' Effect
% Bothered or disturbed
Smoke, fumes or odour Noise Dust and dirt on the inside of the (shop windows/curtains or inside window sills) Dust and dirt on (shelves or goods/furniture or walls) Vibrations
Business
Household
71 86
25 63
88
63
86
44
52
50
'extremely' worried about their local environment and over 70% were 'very' or 'extremely' worried about air pollution from road traffic (a figure exceeded only by rising prices). The second pilot survey question was specifically designed to prioritise local environmental issues by asking respondents to choose the three issues (from a list of ten) which caused them the greatest nuisance when they were out walking in Ealing. For each target group the three greatest nuisances were, litter and rubbish; the amount of road traffic; and smoke, fumes or odour from road traffic. Noise from road traffic came either fourth or fifth, with dust and dirt (generally, not specifically generated by traffic) placed sixth. This question was also modified for the Wood Green householder survey to take into account the magnitude of the respondents' concern. The results for the
Table 4 Response by householders in Wood Green to the question 'Inside your h o m e . . , how often are you bothered or disturbed by the following effects?' Effect
Smoke, fumes and odour from road traffic Noise from road traffic Vibrations from road traffic Dust and dirt from road traffic
Never (%)
Occasionally
Frequently
All the time
(%)
(%)
(%,)
46
34
17
3
20 23 32
37 34 32
29 26 20
14 17 17
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Wood Green site were very similar to those for the pilot survey. The data collected also shows that over 50% of the household respondents were 'very' or 'extremely' bothered by smoke, fumes and odour and the amount of road traffic, and that 45% were similarly bothered by dust and dirt. More detailed questions, designed to establish the specific environmental problems and health effects that bother or disturb the public and to discover if the public attributes these problems and effects to vehicular sources, were then directed to each respondent group. The pilot survey results indicated a very high level of indoor disturbance from noise and dust/dirt, as illustrated in Table 3. Householders were also asked what they thought was the main cause of the effects listed in Table 3. Road traffic was blamed by at least 38% of total household respondents for the noise inside their homes, by 36% for the dust/dirt on furniture or indoor walls and by 50% for dust/dirt on the inside of curtains or inside window sills. The data in Table 3 also seems to indicate that considerably more business people than householders were bothered indoors by the listed effects, particularly in the case of smoke, fumes or odour. Many of the business people questioned worked in shops immediately adjacent to the Broadway and High St roads, where traffic was frequently slowmoving or stationary, and this possibly contributed to their higher level of disturbance. There is also the possibility of a methodological effect since business respondents completed their questionnaires themselves. The question did not, however, give any information about the frequency of disturbance and was therefore modified for the follow-up survey, the results of which are shown in Table 4.
Table 5 Responses to the question 'when you are out walking in Ealing, can you please tell me if you are ever bothered or disturbed by any of these effects?' Effect
%bothered or disturbed
Smoke, fumes or odour Dust and dirt Noise Smog Blackening of building walls
Business
Household Pedestrian
93 93 93 24 38
70 67 81 16 42
69 57 6I 21 33
The figures shown in Table 4 indicate that over 40% of the total Wood Green household respondents were bothered either 'frequently' or 'all the time' by traffic-induced noise, vibrations and dust/dirt inside their homes, and that over 50% of respondents were bothered at least occasionally by indoor smoke, fumes and odour from road traffic. The level of outdoor disturbance in Ealing to all three target groups from a range of effects is listed in Table 5. Business people generally show more disturbance than both householders and pedestrians, which is consistent with the figures for indoor disturbance shown in Table 3. It is evident that practically every business respondent and at least 50% of pedestrians and householders are bothered or disturbed by smoke, fumes or odour, dust/dirt and noise when they are out walking in Ealing. Smog and the blackening of building walls disturb less people, although they still affect 20-40% of respondents. Householders at Wood Green were asked a modified version of the same
Table 6 Response to the question 'when you are out walking in Wood Green, how often are you bothered or disturbed by followingeffects?' Effect
Never (%)
Occasionally Frequently (%) ~°/~,)
All the time (%)
Smoke, fumes and odour Dust and dirt Noise Smog Blackening of building walls
I1 6 17 43 54
52 48 40 37 34
26 29 17 14 3
11 17 26 6 9
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Table 7 Pedestrian response to the question 'in Ealing, what do you think is the main cause of your/the... (name effect)?' (Selected responses shown) Health/nuisance effect
A. Pollution from road traffic
B. Pollution from road traffic and other
C. Pollution/air pollution
D. General dust and dirt
E. Sum of A-D
Sore or runny eyes Sneezing Irritated throat Dirt on your clothes Dirt on your skin, nails or hair
12 6 10 28 26
3 5 6 8 10
4 1 4 4 4
5 8 1 6 4
24 20 21 46 44
tify whether they were bothered by a range of health/nuisance effects when they were indoors. The effects included sore or runny eyes, sneezing, an irritated throat, dirt on clothes/skin, nails or hair, an unpleasant taste in the mouth, headaches and difficulty in breathing. Less than 10% of both respondent groups felt that road traffic was to blame for any of the indoor problems listed above. All three target groups were also asked to consider these health/nuisance effects outdoors. The results for business and household respondents were very similar and there was only a slight increase in annoyance when respondents were asked to consider these effects outdoors rather than indoors. While over 25% of the pedestrian respondents felt that pollution from road traffic was responsible for the dirt on their clothes, skin, nails or hair, concern about health-related effects
question, and the results show a similar pattern, as illustrated in Table 6. Respondents were also asked what they thought caused the outdoor effects listed in Tables 5 and 6. In the pilot survey, 50% of the total pedestrian and household respondents thought that pollution from road traffic was primarily responsible for the smoke, fumes or odour and dust/dirt in Ealing, and between 20 and 30% thought that vehiclegenerated pollution was the main cause of the blackening of building walls. In Wood Green, 74% of the total household respondents blamed road traffic pollution primarily for the smoke, fumes and odour, 31% for the dust and dirt, 40% for smog and 29% for the blackening of building walls. The pedestrian, business and household respondents were asked in the pilot survey to iden-
Table 8 Response of Wood Green householders to the question 'when you are (out walking/inside your home) how much are you bothered or disturbed by the following problems?' Effect
Sore or runny eyes Sneezing Dirt on your clothes Dirt on your skin, nails or hair Irritated throat
Not at all or not very bothered (%)
Moderately bothered (%)
Very or extremely bothered (%)
Outdoors
Indoors
Outdoors
Indoors
Outdoors
Indoors
66 66 51 48
89 89 77 74
23 29 32 29
11 11 14 12
I1 5 17 23
0 0 9 14
57
74
20
14
23
12
I.S. McCrae, LD. Williams/ Sci. Total Environ. 146/147 (1994)81-91
was generally lower, with less than 12% of pedestrians blaming these effects exclusively on vehicle-derived pollution. If, however, we make the assumption that all kerbside air pollution and dust/dirt is traffic generated (a 'worst-case scenario'), it is possible to make an estimate of the maximum percentage of people who blame the listed outdoor effects on vehicle-derived air pollution, as shown in Column E of Table 7. Based on this assumption, the results indicate that possibly 45% of pedestrians blame pollution from road traffic for dirt on their clothes, skin, nails or hair, and 1 in 5 feel that road vehicle pollution is responsible for their sore or runny eyes, sneezing and irritated throat when they are outdoors. This question was again modified for the Wood Green householder survey to assess the magnitude of the respondents' concern about each health/ nuisance effect. Some of the effects used in the pilot survey were also dropped from the question, since the public did not appear to be very concerned about them. The results (shown in Table 8) reinforce the findings of the pilot survey that people are mainly concerned about dust/dirt, although in this survey the difference between indoor and outdoor disturbance is more distinct, with approximately 25% more people being disturbed outdoors than indoors. As in the Ealing survey, only a small number of respondents blamed pollution from road traffic exclusively for the effects listed in Table 8, with the 'worst-case scenario' (outlined above) suggesting that possibly 20-30% of
87
householders feel that vehicle-derived pollution is responsible for the dirt on their clothes, skin, nails or hair, sneezing and irritated throat. In the pilot survey, all three target groups were asked general questions on air pollution. Between 84 and 93% of people felt that there was air pollution in Ealing, with 84-86% of these respondents choosing exhausts from road traffic (from a list of ten) as one of the three main causes of this pollution. The magnitude of the indoor and outdoor nuisance caused to household respondents by smoke, fumes and odour and dust/dirt from road traffic was measured using a seven-point scale at the Wood Green site. The 'average respondent' appeared to be moderately to very bothered about both of these effects outdoors, with smoke, fumes and odour causing slightly more concern than dust/dirt. Householders were less disturbed indoors than outdoors by these effects, with dust and dirt causing marginally more concern than smoke, fumes and odour. The Wood Green householders were also asked to state specifically what it was about dust/dirt or smoke/fumes/odour that disturbed them. Outdoors, 50% of the total respondents were concerned that smoke and fumes from road traffic would damage their health, while indoors people showed more concern about the actual odours produced by air pollution from road traffic. Approximately 25°/, of the respondents were concerned that the outdoor dust/dirt from road traffic would damage their health and 50% complained that vehicle-generated dust and dirt
Table 9 Pollutant concentrations measured using the TRL mobile laboratory Pollutant
Carbon monoxide Nitric oxide Nitrogen dioxide Methane Non-methane hydrocarbons Sulphur dioxide Ozone
Unit
ppm ppb ppm
ppb
Site C
Site B
Site A Mean
Max
N
Mean
Max
N
Mean
Max
N
1.0 32.5 43.2 1.3 0.5
2.3 126.9 75.7 2.2 1.3
5113 5109 5110 4496 4499
2.8 90.7 61.8 1.2 1.1
7.1 191.8 101.0 1.4 2.9
3829 4251 4251 3693 3693
0.9 19.5 39.2 2.3 0.2
2.3 86.9 68.3 3.0 0.6
4797 4804 4804 44[)2 4464
2.5 15.7
7.5 28.9
4253 5124
9.6
-17.0
4255
6.7 14.7
15.4 24.0
3463 4804
Mean, arithmetic mean; Max, maximum 15-min average, N, number of 15-min periods surveyed.
LS. McCrae, LD. Williams/Sci. Total Environ. 146/147 (1994) 81-91
88
Table 10 Smoke concentrations (#g/m3) at the monitored sites Site Ealing Wood Green
Site A Site B Site C
Number of samples
Median
Range
59 39 80
18.0 30.0 16.0
6-42 10-77 7-58
caused indoor soiling to, e.g. walls, doors, windows, and furniture. 3.2 A i r p o l l u t i o n results
The average hourly traffic flow along the roads closest to Sites A, B and C were 470, 462 and 79 vehicles, respectively. Diesel vehicles typically accounted for less than 20% of these flows. The maximum legal speed limit was 30 mph (48 km/h) at each of the sites. A summary of the pollutant concentrations recorded at each of the three sites is indicated in Table 9. The concentrations of all primary pollutants were generally low, which may be explained by the relatively low traffic flows in the immediate vicinity of each site. The concentrations of secondary pollutants (ozone and nitrogen dioxide) were relatively high. This may be explained by the presence of additional sources, other than the local road. Indeed the major thoroughfare, Ealing Broadway, is within half a mile of both Sites A and B and typically has approximately 780 vehicles/h.
A major north-south road passing through Wood Green Shopping City, and carrying a traffic flow of about 1000 vehicles/h, is about 300 m to the west of Site C. At each of the three sites, the weekday traffic flow indicated characteristic morning and evening traffic peaks. A similar distribution was evident during the weekend periods, but with substantially lower traffic flows particularly on Sundays at Sites A and B, although elevated on a Saturday at Site C due to congestion of the main north-south road. Positive and significant correlations were noted between all the primary pollutants and traffic flows at each of the three sites. Smoke and total suspended particulate (TSP) data at all 3 sites are summarised in Tables 10 and 11. The median 24-h smoke and TSP concentrations were higher at the busier commercial site in Ealing (Site B) than at both the residential sites. The 4-h TSP concentrations measured during peak traffic flow were generally higher than the 24-h values, the exception being at site C, where the 24-
Table 11 Total suspended particulate concentrations (/xg/m3) at the monitored sites Site
Sampling period
Numberof samples
Median
Range
Site A
06:00-10:00 16:00-20:00 00:00-24:00 06:00-10:00 16:00-20:00 00:00-24:00 06:00-10:00 16:00-20:00 00:00-24:00
11 12 12 14 16 13 22 23 23
55.2 42.6 35.6 61.2 77.3 45.6 33.2 28.8 29.9
26.9-750.3 a 24.1-1090.8a 21.4-57.7 12.0-105.0 26.1- 146.2 23.2-121.3 15.2-149.9 10.8-131.4 14.3-134.7
Site B Site C
aOn two occasions, extremelyhigh concentrations of TSP were measured extending the data ranges.
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Table 12 Carbonyl compounds (ng/l) at the monitored sites Site
Carbonyl compound
Na
Arithmetic mean
Standard deviation
Range
Site A (17)b
Formaldehyde Acetaldehyde Hexanal Crotonaldehyde Formaldehyde Acetaldehyde Hexanal Crotonaldehyde Formaldehyde Acetaldehyde Hexanal Crotonaldehyde
10 15 12 17 8 9 9 9 33 34 23 36
32.0 5.2 9.2 3.5 29.9 2.9 5.1 1.4 5.0 3.5 3.4 1.5
30.8 5.8 5.3 2.6 36.0 0.6 0.9 0.4 0.5 0.6 0.3 0.1
7.6-116.4 0.9-24.0 3.2-18.2 1.4-11.5 1.7-122.5 1.9-3.9 4.2-6.7 0.7-1.9 0.3-12.9 0.5-20.3 1.7-8.8 0.1-2.9
Site B (9)b
Site C (36)b
aNumber of samples in which compound was detected. bFigures in parentheses refer to the number of samples taken.
h median was similar to the afternoon median. The traffic volumes in both Madeley Road (Site A) and the High Street (Site B) were very similar, although the overall traffic volume in the area surrounding the commercial site was about double that of the residential site. This factor, together with the greater volume of people and the higher percentage of diesel vehicles at the commercial site (11-17%) compared to the residential site (9-10%), probably accounts for the higher levels of smoke and particulates at Site B. The 24-h TSP concentrations are lower than values recorded at other (busier) sites in London [7,9,10]. The ambient carbonyl compound concentrations found during both surveys are summarised in Table 12. The mean values for formaldehyde, acetaldehyde, hexanal and crotonaldehyde were very similar at both the pilot survey locations, although slightly higher at Site A. The mean values found at Wood Green for acetaldehyde, hexanal and crotonaldehyde are similar to those found at Ealing. The formaldehyde value is, however, much lower, but this is probably due to the mean formaldehyde values for both sites at Ealing being strongly influenced by high outlying values. Acrolein, propanal, benzaldehyde and iso-valeraldehyde were not detected at either survey location.
4. Discussion The pilot social survey results indicate that the public are more concerned about social issues such as health/social services, law and order, education and unemployment than issues such as their local environment, which is of medium concern to them. However, traffic related nuisances are important local environmental issues, with 3 of the top 4 local environmental nuisances being vehicle-derived. This was reinforced by the follow-up survey, where over 70% of the household respondents were 'very' or 'extremely' worried about air pollution from road traffic. These results suggest that once people have satisfied their social priorities, environmental (aesthetic) issues become more important, and that road traffic pollution is probably the largest contributor to outdoor public environmental nuisance. The main disturbances to the public from vehicle-derived air pollution are identified as dust/dirt, smoke, fumes or odour and noise. During the business and pedestrian pilot survey period, over 90% of business respondents and 60% of pedestrians complained about outdoor dust/dirt when a median 24-h roadside TSP concentration of 45.6 #g/m 3 was recorded. Indoors, over 80% of
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respondents complained about dust/dirt. Similarly, at least 45-63% of householders complained about indoor dust/dirt when a roadside 24-h median TSP value of 35.6 #g/m 3 was recorded at the Ealing residential site. Road traffic pollution was thought by the respondents to be the main cause of both the indoor and outdoor dust and dirt. At Wood Green, 50% of the total household respondents were disturbed by indoor soiling, considered by them to be caused by vehicle-derived dust/dirt, when a roadside 24-h median TSP value of 29.9 #g/m 3 was recorded. Twenty-five percent of these respondents felt that this dust/dirt damaged their health. The issues of smoke, fumes and odour are more difficult to interpret [3], since the public finds it difficult to decide whether they are disturbed more by visual intrusion (smoke), an unpleasant smell (fumes and odour), a general feeling of discomfort or concerns about health (smoke, fumes and odour). However, the pilot results indicate that 60-90% of the public were disturbed outdoors by smoke, fumes or odour when the mean 24-h smoke concentrations were 18-30 #g/m3 and individual ambient carbonyl compound concentrations ranged from 0.7-123 ng/1. At Wood Green, 90% of household respondents were bothered io some extent by outdoor smoke, fumes and odour when a mean 24-h smoke concentration of 21.9 p,g/m 3 and individual ambient carbonyl concentrations of 0.1-20.3 ng/l were recorded. Inside buildings, 25% of household and 70% of business respondents in Ealing complained about smoke, fumes or odour. Again, road traffic pollution was thought to be the main cause of indoor and outdoor smoke, fumes or odour. The 'worst-case scenario' previously outlined shows that, during the surveys, people generally complained more about dust/dirt than specific health effects when they were out walking, despite the fact that 50% of the Wood Green respondents were worried that traffic-induced smoke and fumes could damage their health. Thus, although people believe that traffic pollution may damage their health, they actually complain more about dust/dirt, and this may indicate that smoke and TSP concentrations are a better indicator of nuisance effects than carbonyl, hydrocarbon or
ozone concentrations. This is in agreement with previous research by Ball and Caswell [11], who suggested that diesel emission standards should be changed from a visibility to a soiling-based criterion, as this is probably a more accurate reflection of the impact that diesel emissions have on the public. Further surveys are planned for 1992, including a commercial site at Wood Green for comparison with the pedestrian and business pilot surveys. The data from all the surveys will eventually be used towards the formulation of a method for the quantification of the nuisance caused to the public by air pollutants generated by road traffic.
5. Acknowledgements The work described in this paper forms part of a Department of Transport funded research programme conducted by the Transport Research Laboratory, and the paper is published by permission of EEA Division and the Chief Executive of TRL. © Crown Copyright 1992. The views expressed in this paper are not necessarily those of the Department of Transport. Extracts from the text may be reproduced, except for commercial purposes, provided the source is acknowledged.
6. References 1 A.M. Mackie and C.H. Davies, Environmental Effects of Traffic Changes, TRRL Report LRI015, Transport and Road Research Laboratory, Crowthorne, Berks, 1981. 2 J. Morton-Williams, B. Hedges and E. Fernando, Road Traffic and the Environment, Social and Community Planning Research, London, 1978. 3 I.D Williams, Road traffic pollution and public nuisance. Clean Air, 21(3) (1991) 123-131. 4 A.M. Mackie and L.J. Griffen, Beforeand After Study of the Environmental Effects of the Tring By-pass, TRRL Report LR746, Transport and Road Research Laboratory, Crowthorne, Berks, 1977. 5 P.G. Hedicar, West Yorkshire Transportation Studies 3. Analysis of Environmental Issues. Traffic Eng. Control, (1979) 82-85. 6 I.S. McCrae and I.D. Williams, Air Pollution from Road Traffic and Public Nuisance, TRL Report (in preparation), Transport Research Laboratory, Crowthorne, Berks, 1992. 7 I.S. McCrae and A.J. Hickman, Air pollution in
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8
9
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