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Exposure–effect relationships between road traffic noise annoyance and noise cost valuations in Valladolid, Spain
Applied Acoustics 67 (2006) 945–958 www.elsevier.com/locate/apacoust
Exposure–effect relationships between road traffic noise annoyance and noise cost valuations in Valladolid, Spain M.A. Martı´n a
a,*
, A. Tarrero a, J. Gonza´lez b, M. Machimbarrena
b
EU Polite´cnica, Departamento de Fı´sica Aplicada, c/Francisco Mendiza´bal s/n, 47014 Valladolid, Spain b ETS Arquitectura, Departamento de Fı´sica Aplicada, Av. Salamanca s/n, 47014 Valladolid, Spain Received 7 March 2005; received in revised form 24 January 2006; accepted 26 January 2006 Available online 3 April 2006
Abstract Environmental noise can produce negative effects on people’s health since it interferes with basic activities such as sleeping, resting, studying and communicating. These effects depend not only on the physical characteristics of the noise itself, but also on parameters associated to each person and each environment. It is thus important to study noise pollution from a quantitative point of view as well as a from the point of view of the annoyance that it produces in the population. We have conducted a social survey aiming to identify the main sound sources, evaluate the annoyance and analyse the main effects of noise on people. The survey was distributed to a sample of people living approximately in the corners of an imaginary 250 m grid placed over the map of the city of Valladolid (Spain). The same corners were used to perform in situ measurements for a noise city map. There are two main purposes for this research work: (1) we want to compare the objective noise measurements to the annoyance reported by the people in order to find some kind of dose–effect relationship, and (2) we want to analyse how the population of Valladolid evaluates noise reduction from an economical and social point of view. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Annoyance due to noise; Dose–effect analysis; Economical valuation of noise
*
Corresponding author. E-mail address: [email protected] (M.A. Martı´n).
0003-682X/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.apacoust.2006.01.004
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1. Introduction According to the existing literature [1,2], the perception of noise and the annoyance that it produces depends not only on physical attributes (sound pressure level, frequency spectrum, temporal evolution. . .) but also to a certain extent on subjective parameters inherent to each person, on the state of mind of the person and on the socio-cultural environment. This is why trying to find some kind of relation between noise exposure indicators and noise annoyance indicators seems a good way to evaluate noise effects. Schulte-Fortkamp [1] has performed several studies concerning noise annoyance, coming to the conclusion that such studies are extremely complicated due to the great amount of parameters involved and to the influence of social, psychological, environmental and cultural factors. Noise annoyance is much too complicated to be described using a single parameter. To describe it properly, it is necessary to use multidisciplinary indicators. Miyara [2] discusses the different methods used, the difficulties encountered and the results obtained when investigating in this field. In the ‘‘International symposium about noise contamination in the cities’’ which was held in Madrid in 2002, the importance of such studies relating measured noise levels and annoyance, was emphasized. Again, dose-effect relationships were demanded. Noise has other effects besides its negative influence on health and quality of life: it has an enormous cost for the society, as it is shown in the abundant literature [3–6]. There have been several attempts to evaluate the social cost of noise and Lambert in [3] exposes the two most frequently used methods: the hedonic prices method and the contingent valuation method. These papers are concerned basically with traffic noise since this is the main cause for noise annoyance. The European Directive on Environmental Noise [7] indicates that future noise maps must include action plans with financial information concerning cost-effectiveness assessment. It is thus necessary to research in this field in order to provide a reference point for politicians and legislators. Having a reference point will undoubtedly help them to decide which solution should be adopted to reduce noise levels in agglomerations and major roads. Articles 6 and 11 of the Directive say respectively: ‘‘Harmful effects may be assessed by means of the dose–effect relations referred to in Annex III’’ and ‘‘The reduction of harmful effects and the cost–effectiveness ratio shall be the main criteria for the selection of the strategies and measures proposed’’. 2. Procedure 2.1. Acoustic parameters measurement Aiming to search for dose–effect relations and to evaluate noise reduction to some extent, we have performed our research using as a starting point (input) the experimental data of the noise map of the city of Valladolid (Spain), which is located about 200 km northwest of Madrid, has about 320,000 people and an area of about 170 km2. The Valladolid noise map w as performed in 2002 at the request of the Castilla and Leo´n Lander authority. The technical specifications sheet required that the measurement points were located on a 250 m sided grid. This size of the grid led to a total amount of 500 points distributed over the metropolitan area of Valladolid. Measurements were made at 490 points placed at the vertexes of each of the squares forming the grid. Due to this
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requirement, some of the measurement points were in the streets, some in green areas (parks), some in places were it was very difficult to enter etc. . . Where the points were located in the streets, the measurement was performed not far from the closest fac¸ade and at a height of 1.2 m. Even though the use of a grid to perform measurements for a noise map was common in the past and even not so long ago [8], nowadays it is more frequent to take into account the effect of sources, density of population and other relevant factors as in the mixed method [9]. However the grid method can be adequate to know the noise levels perceived by the population. The noise levels (Leq, Lmax, L10, L50, L90, Lmin) were measured in dB(A), taking an averaging time of 10 minutes. For each of the 490 measurement points, eight measurements were made as follows: two during the day period of a working day, two during the day period of a holiday, two during the night period of a working day and two during the night period of a holiday. Measurements took place on different months, days of the week and time during the corresponding period. 2.2. Survey procedure To collect the information concerning noise annoyance, we conducted a survey using indications from previous research [10–12,21]. The use of a guide on how to present information about socio-acoustic surveys [13] simplifies the task of comparing our results to others. The survey is structured in eight parts each of which gathers different information: (1) (2) (3) (4) (5) (6) (7) (8)
Dwelling location. Data concerning the person being surveyed. Dwelling description-characteristics. Environment description-characteristics. Annoyance due to the different sound sources. Effects produced by noise on the population being interviewed. Actions taken to reduce noise. Economical valuation of noise reduction.
For the survey we have used approximately the same points as those used in the previously mentioned noise map. Only 296 out of the 490 points resulted in valid surveys, since 196 points laid on parks, roads far from residential areas or industrial areas and 28 other surveys were not answered. For each of these 296 points we have studied the noise measurements (dose) and the annoyance produced in the citizens (effect), and we have then related both indicators. As it has already been mentioned, there is no economical model that enables calculation of the total cost for the society associated with noise exposure. Generally speaking, the benefits are defined from the point of view of the harm that is avoided, assigning an economical value to such harms. The contingent valuation technique uses as input the answers given by citizens when they are asked about how they value the object under analysis. The intention is to investigate how much is a citizen willing to pay in order to reduce such noise. This method is questionable and raises certain controversy since citizens are asked to value something that they do not fully understand or even have not even experienced.
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We have chosen, for each of the 296 previously mentioned measurement points, the closest building and we have distributed the survey among the population in that building randomly. If it was a multistorey building (which was mostly the case), the survey was distributed randomly among the different floors and among the different neighbours in each floor. The minimum age of the people answering the survey had to be 16 years old but there was no upper age limit. The distribution of the surveys according to the age is quite similar to Valladolid’s age distribution, as it can be seen in Fig. 1. In Fig. 2 we can see that the percentage of men answering the survey is slightly higher than that of women. If we consider the cultural level (degree of education) the higher percentage corresponds to citizens with university education and the remaining group is distributed evenly among people with elementary and secondary education, as it can be seen in Fig. 3. According to Figs. 1–3, it can be deduced that as far as age, sex and education level is concerned, the sample used in our survey is heterogeneous enough and is adequate to represent Valladolid’s population. If we consider the actual Leq measured on a working day in those 296 points, it turns out that 42.5% of the people answering the survey are exposed (in their street) to sound pressure levels above 65 dB(A), 47% of them to levels between 55 and 65 dB(A) and only 11% to levels below 55 dB(A). This can be seen in Fig. 4.
Sample 0.25 20,2
0.2
21,4
20,3 17,3
18,2
Valladolid 20,9
21,2 18,1
16,3
0.15
11,8
0.1
6,9 5,7
0.05 1,7 0,0
0
16-20
21-30
31-40
41-50
51-65
>65
NC
Fig. 1. Age distribution of the sample and of Valladolid’s population.
Female 47,3% Male 52,7%
Fig. 2. Male/female distribution of the sample.
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University Level
Secondary Level
38,9%
27,0%
No Answer 1,0%
No Studies
Primary
7,1%
26,0%
Fig. 3. Sample distribution according to the education level.
35%
30,7 26,7
30% 25%
19,9
20% 15%
9,1
10,1
10% 5%
1,7
1,7
0% 45-50
51-55
56-60
61-65
66-70
71-75
76-80 Leq(dBA)
Fig. 4. Percentage of surveys performed as a function of the associated measured daytime Leq in dB(A).
3. Results 3.1. Noise annoyance due to traffic noise In the survey, people were asked about the degree of annoyance produced by several different sources and it turned out that among all of them it is ‘‘general traffic noise’’ which produces greater annoyance. We have then decided to use this noise source (general traffic noise) as a reference to evaluate the annoyance due to noise. We have identified as ‘‘highly annoyed’’ those citizens who answered ‘‘much’’ or ‘‘very much’’ when asked about the annoyance produced by traffic noise. Fig. 5 shows the results: 41.9% of the people interviewed belonged to the group ‘‘highly annoyed’’. Fig. 6 shows the spatial distribution of the annoyance due to noise over the map of Valladolid. This figure gives a visual idea of the areas highly annoyed by noise in the city. Similarly, Fig. 7 shows the areas with measured levels above and below 65 dB(A) on a working
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23,0
25% 20%
22,6
18,9
17,9
17,6
15% 10% 5% 0 0%
Very much
much
fair
little
not at all
not answered
Fig. 5. Annoyance due to traffic noise.
Fig. 6. Highly annoyed and slightly annoyed distribution in the city of Valladolid.
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Fig. 7. Valladolid noise level distribution above and below 65 dB(A).
day. If we compare Figs. 6 and 7 we can conclude that the distribution of ‘‘highly annoyed by noise’’ and ‘‘measured Leq above 65 dB(A)’’ is very similar, although not coincident, since noise annoyance can sometimes be due to other factors besides noise level, as we have already mentioned.
3.2. Relation between measured levels and annoyance As it was previously mentioned, for each point eight measurements were made: four in the day period and four in the night period. Measurements were done on different days, months and at different times within each period. Considering this fact and the fact that we have 490 measurement points, we have decided to approximate the average of all the day measurements to Lday and the average of all the night measurements to Lnight. Then we have calculated Ldn. In order to relate the measured noise levels to the annoyance produced by noise we have made different types of analysis: percentage of highly annoyed as a function of
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Ldn, average annoyance as a function of Ldn, percentage of not very annoyed by noise as a function of Ldn, etc. . . and we have come to the expected conclusion that the best fit is found when we consider the relation between highly annoyed and Ldn. Figs. 8 and 9 represent the average annoyance and the percentage of highly annoyed as a function of Ldn using 2 dB(A) intervals. Table 1 shows how many surveys belong to each interval. The ‘‘average annoyance’’ has been calculated assigning a value of 5 points to the answer ‘‘very much’’, 4 points to ‘‘much’’, 3 point to ‘‘so-so’’, 2 points to ‘‘little’’ and 1 point to ‘‘not at all’’. In spite of the great amount of parameters that can influence the perception of the annoyance due to noise (personal, psychosocial, cultural. . .) it can be considered that
Average Annoyance
5 4 3 2 Ldn(dBA) 1 51
53
55
57
59
61
63
65
67
69
71
73
75
77
Fig. 8. Average annoyance produced by traffic noise as a function of the Ldn in dB(A); Correlation coefficient r = 0.92.
% Highly Annoyed
100 80 60 40 20 Ldn(dBA) 0 55
57
59
61
63
65
67
69
71
73
75
77
Fig. 9. Percentage of people highly annoyed by traffic noise as a function of the Ldn in dB(A); Correlation coefficient r = 0.94.
Table 1 Number of surveys gathered for each 2 dB(A) Ldn interval Leq interval
47–49 49–51 51–53 53–55 55–57 57–59 59–61 61–63 63–65 65–67 67–69 69–71 71–73 73–75 75–77 77–79
Number of surveys
1
1
6
3
16
17
36
38
23
32
40
33
19
17
7
7
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the annoyance relates ‘‘rather well’’ to the measured Ldn values. This relation improves if we consider only the percentage of people highly annoyed as a function of the Ldn. Even if the typical parameter used when studying noise annoyance has been the Leq or Ldn [14] and more recently Lden [7], there is another relevant parameter related to noise annoyance: Lmax. This parameter reveals the noise level peaks in each measurement. Lmax values have been treated in a similar way as Ldn values. Figs. 10 and 11 show the average annoyance and the percentage of people highly annoyed by traffic noise as a function of the obtained Lmax values in 2 dB(A) intervals. In this case, the relation between Lmax and the annoyance is slightly worse than with the Ldn so we will only consider Ldn in the remaining part of our research. In the existing literature about this topic, we have found Schulz’s paper [13] where a third degree polynomic expression is proposed. This expression is obtained from the deep analysis of many data relating the percentage of people highly disturbed by noise with the day–night level Ldn. In a subsequent paper [15], a quadratic fit is suggested between highly annoyed people and Ldn. Miedema in [14,16] follows a similar criteria as in the previously mentioned papers, and considers the noise from different transport media. In reference [16] the percentage of people highly disturbed are related to Lden and Ldn. After studying the research work performed in different countries in this field, Miedema comes to the conclusion that there is a relation between Lden and Ldn for the different types of traffic noise
Average Annoyance
5 4 3 2 Lmax(dBA) 1 69
74
79
84
89
94
Fig. 10. Average annoyance produced by traffic noise as a function of the Lmax in dB(A); Correlation coefficient r = 0.84.
% Highly Annoyed
100 80 60 40 20 Lmax(dBA) 0 69
71
73
75
77
79
81
83
85
87
89
91
93
95
Fig. 11. Percentage of people highly annoyed by noise as a function of the Lmax in dB(A); Correlation coefficient r = 0.82.
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100
98
% 62
57
60
53 36
40 23
20
75
74
80
7 0
13 10
26 18
0 45
50
55
60
Mr. Ruiz Perez´s Results
65
70
75 Lden(dBA)
Our Results
Fig. 12. Percentage of highly annoyed people versus Lden references) and Lden (calculated).
sources (airplanes, railroad, road traffic. . .). For road traffic noise, the relation suggested by Miedema is Lden = Ldn + 0.2 dB. Based in Miedema’s results we have calculated the Lden for all the measurement points where we have an interview result as well. We can now plot the percentage of highly annoyed people as a function of the calculated Lden and compare our results to those found in the existing literature [16,17] concerning road traffic noise. Fig. 12 shows our results together with those of [17]. 3.3. Economical valuation of noise In Spain, there are still very few research projects concerned about the valuation of noise even though the importance of such knowledge is evident and increasingly taken into account before making decisions in fields such as education, transport, health care, [18– 20]. In our field of research, this type of analysis is evidently important, since noise has a great influence in human comfort and the economical resources dedicated to solve noise problem increase every day. In order to facilitate the understanding of the results obtained from our survey, we have made five different groups according to some kind of affinity between the questions/ answers included in each group. (The questions of the survey related to these five topics can be found in Appendix A) (1) Use of some kind of economical valuation variables in order to determine which parameters influence the importance given by the population of Valladolid to living in a silent environment. When faced with the dilemma ‘‘noise versus economical value of a property that is freely offered for living’’, about 54% of the population prefers to live in a silent environment even if the property being offered is of less value. If to this percentage we add those people who chose to live in a slightly noisy environment, it turns out that 84% of the population prefers to live in a silent or slightly noisy place in spite of a lower economical value of the property.
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(2)
(3)
(4)
(5)
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Regarding the dilemma ‘‘noise/distance from the home to the working place’’, 80% of the population finds more important to live in a silent home environment than to live near the working place. In fact 51% of the people prefer to live in a slightly noise environment situated 30 min away from work. When people are asked about paying a higher price on their houses in order to live in a not very noisy place, 52% of them are willing to do so. The quantity they are willing to pay varies from 1% to 15% of the house price. How much are the citizens of Valladolid willing to pay to reduce noise levels and how much do they think that the local administration (city hall) should invest to decrease noise contamination. It is found that 50% of the population agrees on paying between 3 and 96 € per person and per year in order to reduce noise contamination. The other 50% of people includes those who are not willing to pay any quantity, those who would like to pay but declare not to have enough money and the group not answering or not knowing about the question. The average quantity that people would be willing to pay to reduce noise problems is 7.22€ per person and per year (this quantity goes up to 9.81€ if we consider only the group of highly annoyed by noise people). Concerning the question of how much money should the local administration spend to decrease noise contamination, the average value is 9.54€ per person and per year, going up to 11.54 € if we consider only highly annoyed people. This corresponds to 12.66% of the environmental budget of the city and 1.38% of the total city budget. Analysis of the existing relation between three different variables: citizen noise exposure, subjective appreciation of the degree of annoyance and economical valuation. Most of the people highly annoyed are exposed to high noise levels (Ldn above 65 dB(A)). It is clearly seen that the economical level of the citizen is directly related to the kind of solution adopted to reduce noise annoyance. Citizens of the higher economical class always choose more expensive solutions. Actions suggested by the citizens interviewed in order to reduce noise levels. The majority of the population has chosen to detour road traffic, although those living in the centre have taken as first option to build pedestrian streets and those living near the railroad path have chosen to build acoustic barriers. Other relevant items. It is observed that people highly annoyed by noise have started to react actively in order to improve the noise problem, either by complaining to the local authorities, reporting to the police or modifying their homes. A very significant result is that 29% of the people interviewed have undertaken some kind of modifications in their homes to improve sound insulation and 30% have complained or placed a demand on the source causing the problem.
The results obtained as far as how many people are willing to pay some quantity in order to decrease noise and how much they are willing to pay agree with previously published results. According to some studies performed in France [4], only about 38% of the people surveyed agreed on paying higher taxes in order to reduce noise annoyance, and the amount they were willing to afford was 73€ per family and per year. The results for a
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similar study in Spain are shown in [6] and apparently people would agree on paying about 0.19% of the annual income of the family. According to [3] the social cost of traffic noise varies, depending on the method used and the country under study, between 0.1% in France and 1.4% in Germany of the GDP (Gross Domestic Product). Nowadays some of the European countries consider that the social cost of road noise pollution is about 1% of the GDP.
4. Conclusions From the analysis of the annoyance produced by traffic noise we can conclude that: The spatial distribution of ‘‘people highly annoyed by noise’’ and points with Ldn above 65 dB(A) is very similar (both plots present a high degree of coincidence) Ldn relates very well to the annoyance. The relation is better when considering people highly annoyed than when considering average annoyance. Lmax also relates fairly well to annoyance, but in this case the relation improves when considering average annoyance. From the analysis of the results concerning the social and economical valuation of noise, it is noticeable that: It is clearly seen that the population prefers to live in silent environments even if this means living in house of a lower economical value, increasing the distance to their working places or even paying a higher price for the house. 50% of the population is willing to pay money in order to reduce noise contamination. The average quantity considering the total sample is 7.22€ per person and per year. (9.81€ if we only consider people highly disturbed by noise.) According to the survey, the city hall should spend an average of 9.54€ per person and per year to reduce noise contamination (11.54€ if considering only highly disturbed people). This corresponds to 1.38% of the annual city budget. Many of the people referring high annoyance have undertaken some kind of actions to improve their situation concerning noise annoyance. 29% have insulated in some way their dwellings and 30% have placed a complain or a demand against the disturbing source.
Acknowledgement We would like to thank the Environmental Department of the Junta de Castilla y Leo´n for giving us the chance to perform this research.
Appendix A. Extract from the survey Questions related to the economical valuation of noise:
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References [1] Schulte-Fortkamp B. Effects of Urban Acoustic Pollution. Jornadas Internacionales sobre Contaminacio´n Acu´stica en las Ciudades, Madrid, Espan˜a, 2002: p. 17–21. [2] Miyara F. Paradigmas de la investigacio´n de las molestias por ruido. Available from: www.estrucplan.com.ar/Articulos/paradigmas.asp. [3] Lambert J. Annoyance and its cost. Jornadas Internacionales sobre Contaminacio´n Acu´stica en las Ciudades. Madrid, Espan˜a, 2002: p. 41–4. [4] Lambert J, Poisson F, Champelovier P. Valuing benefits of a road traffic noise abatement programme: a contingent valuation survey. In: 17th ICA, Rome, 2001. [5] Navrud S. Economic benefits of a programme to reduce transportation and community noise – a contingent valuation survey. Proceeding of Internoise Nice 2000;5:3395–400. [6] Viladrich-Grau M, et al. How much people are willing to pay for silence? A one – and half-bound DC CV estimate. In: 17th ICA, Rome, 2001. [7] DIRECTIVE 2002/49/EC of the European parliament and of the council of 25 June 2002 relating to the assessment and management of environmental noise. [8] Sommerhoff J, Recuero M, Sua´rez E. Community noise survey of the city of Valdivia, Chile. Applied Acoustics 2004;65:643–56. [9] Trombetta Zannin PH, Belisa’ rio Diniz F, Alves Barbosa W. Environmental noise pollution in the city of Curitiba, Brazil. Applied Acoustics 2002;63:351–8. [10] ISO 15666 Acoustics-Assessment of noise annoyance by means of social and socio-acoustic surveys. ISO/TC 43/SC 1 N 1284, December, 2000. [11] Barrigo´n JM et al. Presentacio´n de una encuesta para la realizacio´n de estudios sociales sobre el impacto del ruido urbano. Revista de Acu´stica 2002;XXXIII Nu´ms 1 y 2. [12] Fields JM, de Jong RG, et al. Guidelines for reporting core information from community noise reaction surveys. J Sound Vib 1997;206(5):685–95. [13] Schultz TJ. Synthesis of social surveys on noise annoyance. J Acoust Soc Am 1978;64(2). [14] Miedema Henk ME, Oudshoorn Catharina GM. Annoyance form Transportation Noise: Relationships with Exposure Metrics DNL and DENL and Their Confidence Intervals. Environ Health Perspect 2001;109(4):409–16. [15] Fidell S, Barber D, Schultz T. Updating a dosage-effect relationship for the prevalence of annoyance due to general transportation noise. J Acoust Soc Am 1991;89:221–33. [16] Miedema HME. Exposure response relations for transportation noise. J Acoust Soc Am 1998;104(6). [17] Ruiz Pe´rez JM. Correlacio´n I´ndice-Molestia’’. Jornadas Internacionales sobre Contaminacio´n Acu´stica en las Ciudades. Madrid, Espan˜a 2002. [18] Costa J, Pigem M. Que´ es y como se realiza un ana´lisis coste-beneficio en sanidad. www.atheneum.doyma.es/ Socios/sala_l/lec05gest.htm. [19] Herranz Pascual K, Proy Rodrı´guez R. Co´mo se puede medir el coste social del ruido de trenes en Espan˜a. Revista especial de Acu´stica 2003;34(3–4). [20] Opinion of the Economic, and Social Committee on the ‘‘Proposal for a Directive of the European Parliament and of the Council of the establishment of rules and procedure with regard to the introduction of noise related operating restrictions at Community airports’’ (COM(2001) 695 final – 2001/0282 (COD)) Official Journal C 125 , 27/05/2002 P. 0014–0016. [21] Fields JM. Recommendations for internationally-shared noise annoyance questions. Internal Doc 1998.
Exposure–effect relationships between road traffic noise annoyance and noise cost valuations in Valladolid, Spain M.A. Martı´n a
a,*
, A. Tarrero a, J. Gonza´lez b, M. Machimbarrena
b
EU Polite´cnica, Departamento de Fı´sica Aplicada, c/Francisco Mendiza´bal s/n, 47014 Valladolid, Spain b ETS Arquitectura, Departamento de Fı´sica Aplicada, Av. Salamanca s/n, 47014 Valladolid, Spain Received 7 March 2005; received in revised form 24 January 2006; accepted 26 January 2006 Available online 3 April 2006
Abstract Environmental noise can produce negative effects on people’s health since it interferes with basic activities such as sleeping, resting, studying and communicating. These effects depend not only on the physical characteristics of the noise itself, but also on parameters associated to each person and each environment. It is thus important to study noise pollution from a quantitative point of view as well as a from the point of view of the annoyance that it produces in the population. We have conducted a social survey aiming to identify the main sound sources, evaluate the annoyance and analyse the main effects of noise on people. The survey was distributed to a sample of people living approximately in the corners of an imaginary 250 m grid placed over the map of the city of Valladolid (Spain). The same corners were used to perform in situ measurements for a noise city map. There are two main purposes for this research work: (1) we want to compare the objective noise measurements to the annoyance reported by the people in order to find some kind of dose–effect relationship, and (2) we want to analyse how the population of Valladolid evaluates noise reduction from an economical and social point of view. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Annoyance due to noise; Dose–effect analysis; Economical valuation of noise
*
Corresponding author. E-mail address: [email protected] (M.A. Martı´n).
0003-682X/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.apacoust.2006.01.004
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1. Introduction According to the existing literature [1,2], the perception of noise and the annoyance that it produces depends not only on physical attributes (sound pressure level, frequency spectrum, temporal evolution. . .) but also to a certain extent on subjective parameters inherent to each person, on the state of mind of the person and on the socio-cultural environment. This is why trying to find some kind of relation between noise exposure indicators and noise annoyance indicators seems a good way to evaluate noise effects. Schulte-Fortkamp [1] has performed several studies concerning noise annoyance, coming to the conclusion that such studies are extremely complicated due to the great amount of parameters involved and to the influence of social, psychological, environmental and cultural factors. Noise annoyance is much too complicated to be described using a single parameter. To describe it properly, it is necessary to use multidisciplinary indicators. Miyara [2] discusses the different methods used, the difficulties encountered and the results obtained when investigating in this field. In the ‘‘International symposium about noise contamination in the cities’’ which was held in Madrid in 2002, the importance of such studies relating measured noise levels and annoyance, was emphasized. Again, dose-effect relationships were demanded. Noise has other effects besides its negative influence on health and quality of life: it has an enormous cost for the society, as it is shown in the abundant literature [3–6]. There have been several attempts to evaluate the social cost of noise and Lambert in [3] exposes the two most frequently used methods: the hedonic prices method and the contingent valuation method. These papers are concerned basically with traffic noise since this is the main cause for noise annoyance. The European Directive on Environmental Noise [7] indicates that future noise maps must include action plans with financial information concerning cost-effectiveness assessment. It is thus necessary to research in this field in order to provide a reference point for politicians and legislators. Having a reference point will undoubtedly help them to decide which solution should be adopted to reduce noise levels in agglomerations and major roads. Articles 6 and 11 of the Directive say respectively: ‘‘Harmful effects may be assessed by means of the dose–effect relations referred to in Annex III’’ and ‘‘The reduction of harmful effects and the cost–effectiveness ratio shall be the main criteria for the selection of the strategies and measures proposed’’. 2. Procedure 2.1. Acoustic parameters measurement Aiming to search for dose–effect relations and to evaluate noise reduction to some extent, we have performed our research using as a starting point (input) the experimental data of the noise map of the city of Valladolid (Spain), which is located about 200 km northwest of Madrid, has about 320,000 people and an area of about 170 km2. The Valladolid noise map w as performed in 2002 at the request of the Castilla and Leo´n Lander authority. The technical specifications sheet required that the measurement points were located on a 250 m sided grid. This size of the grid led to a total amount of 500 points distributed over the metropolitan area of Valladolid. Measurements were made at 490 points placed at the vertexes of each of the squares forming the grid. Due to this
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requirement, some of the measurement points were in the streets, some in green areas (parks), some in places were it was very difficult to enter etc. . . Where the points were located in the streets, the measurement was performed not far from the closest fac¸ade and at a height of 1.2 m. Even though the use of a grid to perform measurements for a noise map was common in the past and even not so long ago [8], nowadays it is more frequent to take into account the effect of sources, density of population and other relevant factors as in the mixed method [9]. However the grid method can be adequate to know the noise levels perceived by the population. The noise levels (Leq, Lmax, L10, L50, L90, Lmin) were measured in dB(A), taking an averaging time of 10 minutes. For each of the 490 measurement points, eight measurements were made as follows: two during the day period of a working day, two during the day period of a holiday, two during the night period of a working day and two during the night period of a holiday. Measurements took place on different months, days of the week and time during the corresponding period. 2.2. Survey procedure To collect the information concerning noise annoyance, we conducted a survey using indications from previous research [10–12,21]. The use of a guide on how to present information about socio-acoustic surveys [13] simplifies the task of comparing our results to others. The survey is structured in eight parts each of which gathers different information: (1) (2) (3) (4) (5) (6) (7) (8)
Dwelling location. Data concerning the person being surveyed. Dwelling description-characteristics. Environment description-characteristics. Annoyance due to the different sound sources. Effects produced by noise on the population being interviewed. Actions taken to reduce noise. Economical valuation of noise reduction.
For the survey we have used approximately the same points as those used in the previously mentioned noise map. Only 296 out of the 490 points resulted in valid surveys, since 196 points laid on parks, roads far from residential areas or industrial areas and 28 other surveys were not answered. For each of these 296 points we have studied the noise measurements (dose) and the annoyance produced in the citizens (effect), and we have then related both indicators. As it has already been mentioned, there is no economical model that enables calculation of the total cost for the society associated with noise exposure. Generally speaking, the benefits are defined from the point of view of the harm that is avoided, assigning an economical value to such harms. The contingent valuation technique uses as input the answers given by citizens when they are asked about how they value the object under analysis. The intention is to investigate how much is a citizen willing to pay in order to reduce such noise. This method is questionable and raises certain controversy since citizens are asked to value something that they do not fully understand or even have not even experienced.
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We have chosen, for each of the 296 previously mentioned measurement points, the closest building and we have distributed the survey among the population in that building randomly. If it was a multistorey building (which was mostly the case), the survey was distributed randomly among the different floors and among the different neighbours in each floor. The minimum age of the people answering the survey had to be 16 years old but there was no upper age limit. The distribution of the surveys according to the age is quite similar to Valladolid’s age distribution, as it can be seen in Fig. 1. In Fig. 2 we can see that the percentage of men answering the survey is slightly higher than that of women. If we consider the cultural level (degree of education) the higher percentage corresponds to citizens with university education and the remaining group is distributed evenly among people with elementary and secondary education, as it can be seen in Fig. 3. According to Figs. 1–3, it can be deduced that as far as age, sex and education level is concerned, the sample used in our survey is heterogeneous enough and is adequate to represent Valladolid’s population. If we consider the actual Leq measured on a working day in those 296 points, it turns out that 42.5% of the people answering the survey are exposed (in their street) to sound pressure levels above 65 dB(A), 47% of them to levels between 55 and 65 dB(A) and only 11% to levels below 55 dB(A). This can be seen in Fig. 4.
Sample 0.25 20,2
0.2
21,4
20,3 17,3
18,2
Valladolid 20,9
21,2 18,1
16,3
0.15
11,8
0.1
6,9 5,7
0.05 1,7 0,0
0
16-20
21-30
31-40
41-50
51-65
>65
NC
Fig. 1. Age distribution of the sample and of Valladolid’s population.
Female 47,3% Male 52,7%
Fig. 2. Male/female distribution of the sample.
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University Level
Secondary Level
38,9%
27,0%
No Answer 1,0%
No Studies
Primary
7,1%
26,0%
Fig. 3. Sample distribution according to the education level.
35%
30,7 26,7
30% 25%
19,9
20% 15%
9,1
10,1
10% 5%
1,7
1,7
0% 45-50
51-55
56-60
61-65
66-70
71-75
76-80 Leq(dBA)
Fig. 4. Percentage of surveys performed as a function of the associated measured daytime Leq in dB(A).
3. Results 3.1. Noise annoyance due to traffic noise In the survey, people were asked about the degree of annoyance produced by several different sources and it turned out that among all of them it is ‘‘general traffic noise’’ which produces greater annoyance. We have then decided to use this noise source (general traffic noise) as a reference to evaluate the annoyance due to noise. We have identified as ‘‘highly annoyed’’ those citizens who answered ‘‘much’’ or ‘‘very much’’ when asked about the annoyance produced by traffic noise. Fig. 5 shows the results: 41.9% of the people interviewed belonged to the group ‘‘highly annoyed’’. Fig. 6 shows the spatial distribution of the annoyance due to noise over the map of Valladolid. This figure gives a visual idea of the areas highly annoyed by noise in the city. Similarly, Fig. 7 shows the areas with measured levels above and below 65 dB(A) on a working
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23,0
25% 20%
22,6
18,9
17,9
17,6
15% 10% 5% 0 0%
Very much
much
fair
little
not at all
not answered
Fig. 5. Annoyance due to traffic noise.
Fig. 6. Highly annoyed and slightly annoyed distribution in the city of Valladolid.
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Fig. 7. Valladolid noise level distribution above and below 65 dB(A).
day. If we compare Figs. 6 and 7 we can conclude that the distribution of ‘‘highly annoyed by noise’’ and ‘‘measured Leq above 65 dB(A)’’ is very similar, although not coincident, since noise annoyance can sometimes be due to other factors besides noise level, as we have already mentioned.
3.2. Relation between measured levels and annoyance As it was previously mentioned, for each point eight measurements were made: four in the day period and four in the night period. Measurements were done on different days, months and at different times within each period. Considering this fact and the fact that we have 490 measurement points, we have decided to approximate the average of all the day measurements to Lday and the average of all the night measurements to Lnight. Then we have calculated Ldn. In order to relate the measured noise levels to the annoyance produced by noise we have made different types of analysis: percentage of highly annoyed as a function of
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Ldn, average annoyance as a function of Ldn, percentage of not very annoyed by noise as a function of Ldn, etc. . . and we have come to the expected conclusion that the best fit is found when we consider the relation between highly annoyed and Ldn. Figs. 8 and 9 represent the average annoyance and the percentage of highly annoyed as a function of Ldn using 2 dB(A) intervals. Table 1 shows how many surveys belong to each interval. The ‘‘average annoyance’’ has been calculated assigning a value of 5 points to the answer ‘‘very much’’, 4 points to ‘‘much’’, 3 point to ‘‘so-so’’, 2 points to ‘‘little’’ and 1 point to ‘‘not at all’’. In spite of the great amount of parameters that can influence the perception of the annoyance due to noise (personal, psychosocial, cultural. . .) it can be considered that
Average Annoyance
5 4 3 2 Ldn(dBA) 1 51
53
55
57
59
61
63
65
67
69
71
73
75
77
Fig. 8. Average annoyance produced by traffic noise as a function of the Ldn in dB(A); Correlation coefficient r = 0.92.
% Highly Annoyed
100 80 60 40 20 Ldn(dBA) 0 55
57
59
61
63
65
67
69
71
73
75
77
Fig. 9. Percentage of people highly annoyed by traffic noise as a function of the Ldn in dB(A); Correlation coefficient r = 0.94.
Table 1 Number of surveys gathered for each 2 dB(A) Ldn interval Leq interval
47–49 49–51 51–53 53–55 55–57 57–59 59–61 61–63 63–65 65–67 67–69 69–71 71–73 73–75 75–77 77–79
Number of surveys
1
1
6
3
16
17
36
38
23
32
40
33
19
17
7
7
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the annoyance relates ‘‘rather well’’ to the measured Ldn values. This relation improves if we consider only the percentage of people highly annoyed as a function of the Ldn. Even if the typical parameter used when studying noise annoyance has been the Leq or Ldn [14] and more recently Lden [7], there is another relevant parameter related to noise annoyance: Lmax. This parameter reveals the noise level peaks in each measurement. Lmax values have been treated in a similar way as Ldn values. Figs. 10 and 11 show the average annoyance and the percentage of people highly annoyed by traffic noise as a function of the obtained Lmax values in 2 dB(A) intervals. In this case, the relation between Lmax and the annoyance is slightly worse than with the Ldn so we will only consider Ldn in the remaining part of our research. In the existing literature about this topic, we have found Schulz’s paper [13] where a third degree polynomic expression is proposed. This expression is obtained from the deep analysis of many data relating the percentage of people highly disturbed by noise with the day–night level Ldn. In a subsequent paper [15], a quadratic fit is suggested between highly annoyed people and Ldn. Miedema in [14,16] follows a similar criteria as in the previously mentioned papers, and considers the noise from different transport media. In reference [16] the percentage of people highly disturbed are related to Lden and Ldn. After studying the research work performed in different countries in this field, Miedema comes to the conclusion that there is a relation between Lden and Ldn for the different types of traffic noise
Average Annoyance
5 4 3 2 Lmax(dBA) 1 69
74
79
84
89
94
Fig. 10. Average annoyance produced by traffic noise as a function of the Lmax in dB(A); Correlation coefficient r = 0.84.
% Highly Annoyed
100 80 60 40 20 Lmax(dBA) 0 69
71
73
75
77
79
81
83
85
87
89
91
93
95
Fig. 11. Percentage of people highly annoyed by noise as a function of the Lmax in dB(A); Correlation coefficient r = 0.82.
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100
98
% 62
57
60
53 36
40 23
20
75
74
80
7 0
13 10
26 18
0 45
50
55
60
Mr. Ruiz Perez´s Results
65
70
75 Lden(dBA)
Our Results
Fig. 12. Percentage of highly annoyed people versus Lden references) and Lden (calculated).
sources (airplanes, railroad, road traffic. . .). For road traffic noise, the relation suggested by Miedema is Lden = Ldn + 0.2 dB. Based in Miedema’s results we have calculated the Lden for all the measurement points where we have an interview result as well. We can now plot the percentage of highly annoyed people as a function of the calculated Lden and compare our results to those found in the existing literature [16,17] concerning road traffic noise. Fig. 12 shows our results together with those of [17]. 3.3. Economical valuation of noise In Spain, there are still very few research projects concerned about the valuation of noise even though the importance of such knowledge is evident and increasingly taken into account before making decisions in fields such as education, transport, health care, [18– 20]. In our field of research, this type of analysis is evidently important, since noise has a great influence in human comfort and the economical resources dedicated to solve noise problem increase every day. In order to facilitate the understanding of the results obtained from our survey, we have made five different groups according to some kind of affinity between the questions/ answers included in each group. (The questions of the survey related to these five topics can be found in Appendix A) (1) Use of some kind of economical valuation variables in order to determine which parameters influence the importance given by the population of Valladolid to living in a silent environment. When faced with the dilemma ‘‘noise versus economical value of a property that is freely offered for living’’, about 54% of the population prefers to live in a silent environment even if the property being offered is of less value. If to this percentage we add those people who chose to live in a slightly noisy environment, it turns out that 84% of the population prefers to live in a silent or slightly noisy place in spite of a lower economical value of the property.
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(3)
(4)
(5)
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Regarding the dilemma ‘‘noise/distance from the home to the working place’’, 80% of the population finds more important to live in a silent home environment than to live near the working place. In fact 51% of the people prefer to live in a slightly noise environment situated 30 min away from work. When people are asked about paying a higher price on their houses in order to live in a not very noisy place, 52% of them are willing to do so. The quantity they are willing to pay varies from 1% to 15% of the house price. How much are the citizens of Valladolid willing to pay to reduce noise levels and how much do they think that the local administration (city hall) should invest to decrease noise contamination. It is found that 50% of the population agrees on paying between 3 and 96 € per person and per year in order to reduce noise contamination. The other 50% of people includes those who are not willing to pay any quantity, those who would like to pay but declare not to have enough money and the group not answering or not knowing about the question. The average quantity that people would be willing to pay to reduce noise problems is 7.22€ per person and per year (this quantity goes up to 9.81€ if we consider only the group of highly annoyed by noise people). Concerning the question of how much money should the local administration spend to decrease noise contamination, the average value is 9.54€ per person and per year, going up to 11.54 € if we consider only highly annoyed people. This corresponds to 12.66% of the environmental budget of the city and 1.38% of the total city budget. Analysis of the existing relation between three different variables: citizen noise exposure, subjective appreciation of the degree of annoyance and economical valuation. Most of the people highly annoyed are exposed to high noise levels (Ldn above 65 dB(A)). It is clearly seen that the economical level of the citizen is directly related to the kind of solution adopted to reduce noise annoyance. Citizens of the higher economical class always choose more expensive solutions. Actions suggested by the citizens interviewed in order to reduce noise levels. The majority of the population has chosen to detour road traffic, although those living in the centre have taken as first option to build pedestrian streets and those living near the railroad path have chosen to build acoustic barriers. Other relevant items. It is observed that people highly annoyed by noise have started to react actively in order to improve the noise problem, either by complaining to the local authorities, reporting to the police or modifying their homes. A very significant result is that 29% of the people interviewed have undertaken some kind of modifications in their homes to improve sound insulation and 30% have complained or placed a demand on the source causing the problem.
The results obtained as far as how many people are willing to pay some quantity in order to decrease noise and how much they are willing to pay agree with previously published results. According to some studies performed in France [4], only about 38% of the people surveyed agreed on paying higher taxes in order to reduce noise annoyance, and the amount they were willing to afford was 73€ per family and per year. The results for a
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similar study in Spain are shown in [6] and apparently people would agree on paying about 0.19% of the annual income of the family. According to [3] the social cost of traffic noise varies, depending on the method used and the country under study, between 0.1% in France and 1.4% in Germany of the GDP (Gross Domestic Product). Nowadays some of the European countries consider that the social cost of road noise pollution is about 1% of the GDP.
4. Conclusions From the analysis of the annoyance produced by traffic noise we can conclude that: The spatial distribution of ‘‘people highly annoyed by noise’’ and points with Ldn above 65 dB(A) is very similar (both plots present a high degree of coincidence) Ldn relates very well to the annoyance. The relation is better when considering people highly annoyed than when considering average annoyance. Lmax also relates fairly well to annoyance, but in this case the relation improves when considering average annoyance. From the analysis of the results concerning the social and economical valuation of noise, it is noticeable that: It is clearly seen that the population prefers to live in silent environments even if this means living in house of a lower economical value, increasing the distance to their working places or even paying a higher price for the house. 50% of the population is willing to pay money in order to reduce noise contamination. The average quantity considering the total sample is 7.22€ per person and per year. (9.81€ if we only consider people highly disturbed by noise.) According to the survey, the city hall should spend an average of 9.54€ per person and per year to reduce noise contamination (11.54€ if considering only highly disturbed people). This corresponds to 1.38% of the annual city budget. Many of the people referring high annoyance have undertaken some kind of actions to improve their situation concerning noise annoyance. 29% have insulated in some way their dwellings and 30% have placed a complain or a demand against the disturbing source.
Acknowledgement We would like to thank the Environmental Department of the Junta de Castilla y Leo´n for giving us the chance to perform this research.
Appendix A. Extract from the survey Questions related to the economical valuation of noise:
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References [1] Schulte-Fortkamp B. Effects of Urban Acoustic Pollution. Jornadas Internacionales sobre Contaminacio´n Acu´stica en las Ciudades, Madrid, Espan˜a, 2002: p. 17–21. [2] Miyara F. Paradigmas de la investigacio´n de las molestias por ruido. Available from: www.estrucplan.com.ar/Articulos/paradigmas.asp. [3] Lambert J. Annoyance and its cost. Jornadas Internacionales sobre Contaminacio´n Acu´stica en las Ciudades. Madrid, Espan˜a, 2002: p. 41–4. [4] Lambert J, Poisson F, Champelovier P. Valuing benefits of a road traffic noise abatement programme: a contingent valuation survey. In: 17th ICA, Rome, 2001. [5] Navrud S. Economic benefits of a programme to reduce transportation and community noise – a contingent valuation survey. Proceeding of Internoise Nice 2000;5:3395–400. [6] Viladrich-Grau M, et al. How much people are willing to pay for silence? A one – and half-bound DC CV estimate. In: 17th ICA, Rome, 2001. [7] DIRECTIVE 2002/49/EC of the European parliament and of the council of 25 June 2002 relating to the assessment and management of environmental noise. [8] Sommerhoff J, Recuero M, Sua´rez E. Community noise survey of the city of Valdivia, Chile. Applied Acoustics 2004;65:643–56. [9] Trombetta Zannin PH, Belisa’ rio Diniz F, Alves Barbosa W. Environmental noise pollution in the city of Curitiba, Brazil. Applied Acoustics 2002;63:351–8. [10] ISO 15666 Acoustics-Assessment of noise annoyance by means of social and socio-acoustic surveys. ISO/TC 43/SC 1 N 1284, December, 2000. [11] Barrigo´n JM et al. Presentacio´n de una encuesta para la realizacio´n de estudios sociales sobre el impacto del ruido urbano. Revista de Acu´stica 2002;XXXIII Nu´ms 1 y 2. [12] Fields JM, de Jong RG, et al. Guidelines for reporting core information from community noise reaction surveys. J Sound Vib 1997;206(5):685–95. [13] Schultz TJ. Synthesis of social surveys on noise annoyance. J Acoust Soc Am 1978;64(2). [14] Miedema Henk ME, Oudshoorn Catharina GM. Annoyance form Transportation Noise: Relationships with Exposure Metrics DNL and DENL and Their Confidence Intervals. Environ Health Perspect 2001;109(4):409–16. [15] Fidell S, Barber D, Schultz T. Updating a dosage-effect relationship for the prevalence of annoyance due to general transportation noise. J Acoust Soc Am 1991;89:221–33. [16] Miedema HME. Exposure response relations for transportation noise. J Acoust Soc Am 1998;104(6). [17] Ruiz Pe´rez JM. Correlacio´n I´ndice-Molestia’’. Jornadas Internacionales sobre Contaminacio´n Acu´stica en las Ciudades. Madrid, Espan˜a 2002. [18] Costa J, Pigem M. Que´ es y como se realiza un ana´lisis coste-beneficio en sanidad. www.atheneum.doyma.es/ Socios/sala_l/lec05gest.htm. [19] Herranz Pascual K, Proy Rodrı´guez R. Co´mo se puede medir el coste social del ruido de trenes en Espan˜a. Revista especial de Acu´stica 2003;34(3–4). [20] Opinion of the Economic, and Social Committee on the ‘‘Proposal for a Directive of the European Parliament and of the Council of the establishment of rules and procedure with regard to the introduction of noise related operating restrictions at Community airports’’ (COM(2001) 695 final – 2001/0282 (COD)) Official Journal C 125 , 27/05/2002 P. 0014–0016. [21] Fields JM. Recommendations for internationally-shared noise annoyance questions. Internal Doc 1998.