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The effect of reducing petrol lead on airborne lead in Wales, U.K.
The Science of the Total Environment, 68 (1988) 71-77 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
71
T H E E F F E C T O F R E D U C I N G P E T R O L L E A D ON A I R B O R N E L E A D IN W A L E S , U.K.
R.A. PAGE
Welsh Office, Cathay's Park, Cardiff CF1 3NQ (United Kingdom) P.A. CAWSE and S.J. BAKER
AERE Harwell, Didcot, Oxon. (United Kingdom) (Received July 17th, 1987; accepted September 1st, 1987)
ABSTRACT Airborne lead has been measured at four urban, one semi-urban and one rural site in Wales during 1984, 1985 and 1986 to assess the effectof the reduction in lead additives in petrol which was required by an E C Directive at the beginning of 1986. The results showed a 52-61% fallin air lead in accord with the 6 3 % reduction in petrol lead.
INTRODUCTION
Concentrations of lead in air particulate were measured continuously during 1984, 1985 and 1986, at six sampling stations throughout Wales. Four of the sites are situated at urban locations at Queensferry (Clwyd); Wrexham (Clwyd); Bedwas (Mid Glamorgan); and at Velindre, near Port Talbot (West Glamorgan): a semi-urban sampling station is located at Trebanos (West Glamorgan). The rural 'background' is measured at Plynlimon (Powys). The objectives of this project are: (i) to record the decrease in lead concentrations in air which may occur in response to the reduced concentration of lead additives in petrol, which was required by EC Directive 85/210/EEC at the beginning of 1986; (ii) to conform with an EC Directive 82/844/EEC that requires measurement of urban lead levels in air to assess hazards to health; (iii) to compare the elevation in urban air concentrations of lead with levels at a rural location (Plynlimon) in central Wales. METHODS
OF SAMPLING
AND
ANALYSIS
The air particulate samplers consist of a plastic holder containing a cellulose filter (6 cm diameter, Whatman 40), through which air is drawn by a pump at a rate of about 61rain -1. The exact air flow rate is measured by a gas meter. The sampling equipment requires a mains electricity supply for its operation and has to be reasonably vandal-proof.
0048-9697/88/$03.50
© 1988 Elsevier Science Publishers B.V.,
Plynlimon, Powys Trebanos, W. Glam Queensferry, Clwyd Wrexham, Clwyd Bedwas, Mid Glare Port Talbot, W. Glam (Velindre)
Station
Non-urban Semi-urban Urban Urban Urban Urban
Site type
40 129 636 259 254 163 92 99 619 194 185 137
39 82 612 196 152 119
12 83 320 194 297 157
37 74 803 324 307 154
JanuaryMarch
OctoberDecember
January March
J u ly September
1985
1984 AprilJune
Quarterly concentrations (ng m-3) of lead in air near ground level
TABLE 1
19 61 546 158 158 125
AprilJune 18 77 618 153 222 158
J u ly September
19 111 614 261 210 145
OctoberDecember
15 40 248 85 89 73
JanuaryMarch
1986
17 37 282 99 74 69
AprilJune
15 39 290 93 47 59
July September
9 40 170 97 143 76
OctoberDecember
t~
73 TABLE 2 Mean concentrations of lead in air near ground level during 1964, 1985 and 1986 Station
Plynlimon, P o w y s Trebanos, W. G l a m Queensferry, Clwyd Wrexham, Clwyd Bedwas, Mid Glare Port Talbot, W. Glare (Velindre)
Site type
Non-urban Semi-urban Urban Urban Urban Urban
Mean conc. (ngm -3) 1984
1985
1986
% decrease in mean quarterly Pb conc. in 1986, relative to that during 1984/5
46 98 547 211 222 144
23 81 645 223 224 146
14 39 248 92 88 69
59 56 58 58 61 52
Sampling is continuous with the filters being changed monthly, with assistance from local E n v i r o n m e n t a l H e a l t h Departments. The filters collected during each 3 m o n t h period are bulked as follows to give four samples for each year. A q u a r t e r of each monthly sample is bulked and analysed for lead by X-ray fluorescence. The remainder of each m ont hl y sample is retained for any repeat measurements or f u r t h e r analyses of heavy metals t h a t may be required in the future: monthly samples can therefore still be analysed retrospectively if necessary, e.g. over winter periods of relatively high concentrations. RESULTS Lead in air Table 1 shows the qua r t er l y c o n c e n t r a t i o n s of lead (ngm -3) in air near ground level at the six sampling sites from 1984 to 1986. Generally, the annual average c o n c e n t r a t i o n remained fairly const ant at urban sites t h r o u g h o u t 1984 and 1985 (Table 2). However, lead concent rat i ons decreased at all urban and semi-urban sampling locations at the beginning of 1986 at which time the maximum permitted level for lead in petrol was reduced from 0.40 to 0.15 g 1-1 (Table 3). Lead in air at the four u r b a n sites is averaged for comparison (Fig. 1) with levels at the semi-urban and rural sampling stations. Considering the 2 years of measurements immediately before the decrease in lead, the highest annual average c o n c e n t r a t i o n of lead over the period 1984-85 was found at Queensferry (645 ng m -3) where the sampling site is near to a busy mo to r way and road junction. Compared with the rural 'background' levels at Plynlimon, the ur ba n lead concent rat i ons in 1984-85 show an order of magnitude increase but do not r e a c h more t h a n 32% of the limit set by the EEC ( 2 g g m -3) for control of danger to public health. It should be recognised t hat the data presented here are q u a r t e r l y mean values and it is possible t h a t mo n th ly air lead levels have at t ai ned higher values. At Plynlimon, the r ur al location, lead concent rat i ons decreased by 50% in 1985 compared with the previous year; this is not attributed to any decline in
74 TABLE 3 Lead in petrol Period
Maximum amount (g Pb/1 fuel)
Average amount (gPb/1 fuel)
1972 1 Apr 76-29 Nov 76 30 Nov 76-31 Dec 76 1 Jan 77-31 Dec 77 1 Jan 78-31 Dec 78 1 Jan 79-31 Dec 79 1 Jan 80-31 Dec 80 1 Jan 81-31 Mar 81 1 Jan 86-present time
0.84 0.55a 0.50b 0.50 0.45c 0.45 0.45 0.40d 0.15d
0.48 0.45 0.45 0.42 0.41 0.41 0.37
aNot a statutory requirement but required as part of British Standard 4040. bStatutory under Motor Fuel (Lead Content in Petrol) Regulations 1976. cStatutory under Motor Fuel (Lead Content in Petrol) Regulations 1976. dRequired by EEC regulations. lead in e x h a u s t emissions from m o t o r vehicles b u t r a t h e r to a decline in the c o n t r i b u t i o n from a n o t h e r source, n a m e l y coal b u r n i n g . The period of lower lead levels at P l y n l i m o n in 1985 does c o r r e s p o n d with the m i n e r s strike w h i c h c a u s e d a r e d u c t i o n in emissions from c o a l - b u r n i n g p o w e r stations. The h i s t o r i c a l i n f o r m a t i o n on lead in petrol in Table 3 shows t h a t a r e d u c t i o n o f 63% in lead additive o c c u r r e d on 1 J a n u a r y 1986. In L o n d o n over the first few m o n t h s of 1986, the lead-in-air c o n c e n t r a t i o n s were from 34 to 55% l o w e r t h a n in 1985 (New Scientist, 10 J u l y 1986, p. 21). Table 2 a n d Fig. 1 s h o w t h a t the p e r c e n t a g e decreases in m e a n q u a r t e r l y air c o n c e n t r a t i o n s of lead in 1986 were in the r a n g e 52-61% in Wales, w h i c h is c o n s i s t e n t with the r e d u c t i o n in petrol lead additive of 63%. It was to be expected t h a t the d e c r e a s e in 1986 w o u l d n o t a t t a i n 63% o w i n g to c o n t r i b u t i o n s from o t h e r s o u r c e s to the lead levels measured, e.g. coal b u r n i n g , m e t a l w o r k i n g a n d i n c i n e r a t i o n . As described above, a t P l y n l i m o n lead c o n c e n t r a t i o n s in 1985 were o n l y 50% of t h o s e r e c o r d e d in 1984, but, nevertheless, c o n c e n t r a t i o n s in 1986 still s h o w e d a d e c r e a s e in lead r e l a t i v e to 1985. I n 1972-1973, lead c o n c e n t r a t i o n s in air m e a s u r e d at P l y n l i m o n a n d T r e b a n o s were 52 and 1 8 5 n g m -a r e s p e c t i v e l y (Cawse, 1974), or 3 to 4-fold g r e a t e r t h a n in 1986.
Seasonal influence on atmospheric lead A t u r b a n a n d s e m i - u r b a n s a m p l i n g s t a t i o n s a s e a s o n a l influence is a p p a r e n t w i t h h i g h e r c o n c e n t r a t i o n s of lead in air d u r i n g some w i n t e r periods (Table 4). This s e a s o n a l effect c a n be explained to a l a r g e e x t e n t by r e d u c e d a t m o s p h e r i c dispersion u n d e r c o n d i t i o n s of p e r s i s t e n t low i n v e r s i o n layers t h a t c o m m o n l y o c c u r in w i n t e r m o n t h s and by i n c r e a s e d domestic h e a t i n g and p o w e r
$I
10
100
1984
- 46 (1984)
[
1985
~ i 23 (1985)
J
1986
~ : 14 (1986)
I 1121314J I 1994
= 98 (1984)
~ - 39 (1986)
I [213 i4i11219141 1999 1989
~ = 81 (1985)
TREBANOB (BEMI-URBAN)
Fig. 1. Quarterly concentrations of lead in air near ground level, 1984 to 1986.
(.,I
c v
o=
E QI
?
1000 -
PLYNLIMON ( N O N - U R B A N )
I
112131411 1904
- 281
J
1213[41 19es
~ = 310
J
125
s 12131 ages
~ :
U R B A N 81TE8 ( M E A N )
10
100
"~ 1 0 0 0
76 TABLE 4 Ratios o f ' w i n t e r ' and 'summer' concentrations of lead in air near ground level during 1984 and 1985 Station
Conc. of Pb in ~winter' Conc. of Pb in ~summer'
Plynlimon, Powys Trebanos, W. Glam Queensferry, Clwyd Wrexham, Clwyd Bedwas, Mid Glam Port Talbot, W. Glam (Velindre)
1984
1985
1986
0.40 1.2 0.78 1.2 1.6 1.3
1.5 1.3 1.2 1.9 1.4 1.1
0.75 1.1 0.73 0.97 1.9 1.2
'winter' period includes ( J a n u a r y to March) and (October to December) quarters. 'summer' period includes (April to June) and (July to September) quarters. TABLE 5 Ratios of u r b a n / r u r a l air concentrations of lead Station
Year
Mean a n n u a l conc. of Pb at u r b a n site Mean a n n u a l conc. of Pb at Plynlimon
Trebanos
1984 1985 1986 1984 1985 1986 1984 1985 1986 1984 1985 1986 1984 1985 1986
2.1 3.5 2.8 3.1 6.3 4.9 4.6 9.7 6.6 4.8 9.7 6.3 12.0 28.0 18.0
Velindre
Wrexham
Bedwas
Queensferry
consumption, particularly in coal burning areas such as Bedwas, which shows consistently elevated levels of lead in air during all three winters.
Increases in lead from urban activity Table 5 lists ratios of the annual average concentrations of lead in air observed at the urban sites to the rural 'background' at Plynlimon. Lead concentrations in air at Queensferry in 1985 were almost 30 times greater than
77 a t P l y n l i m o n d u r i n g t h e c o r r e s p o n d i n g s a m p l i n g period, a n d b e t w e e n 2-fold a n d 10-fold i n c r e a s e s in c o n c e n t r a t i o n s a b o v e t h e P l y n l i m o n ' b a c k g r o u n d ' w e r e o b s e r v e d a t t h e o t h e r u r b a n sites. T h e s e e l e v a t i o n s a r e a t t r i b u t e d to v e h i c l e e x h a u s t emissions. CONCLUSIONS T h e p r e s e n t s t u d y h a s s h o w n t h a t t h e r e c e n t d e c r e a s e in lead c o n c e n t r a t i o n s in p e t r o l h a s r e s u l t e d in a fall of 52-61% in a i r lead m e a s u r e d a t u r b a n a n d s e m i - u r b a n l o c a t i o n s in W a l e s in a c c o r d w i t h t h e 63% r e d u c t i o n in p e t r o l lead w h i c h o c c u r r e d a t t h e b e g i n n i n g of 1986. I t will be i n t e r e s t i n g to see w h e t h e r b l o o d lead c o n c e n t r a t i o n s of u r b a n p o p u l a t i o n s fall in s y m p a t h y w i t h t h i s identified r e d u c t i o n in a i r lead c o n c e n t r a t i o n s . ACKNOWLEDGEMENTS T h e a u t h o r s w o u l d like to t h a n k t h e E n v i r o n m e n t a l H e a l t h D e p a r t m e n t s of e a c h of t h e L o c a l A u t h o r i t i e s i n v o l v e d for t h e i r a s s i s t a n c e w i t h s a m p l i n g o p e r a t i o n s . T h i s p a p e r w a s w r i t t e n a n d p u b l i s h e d w i t h t h e a g r e e m e n t of W e l s h Office w h i c h p r o v i d e d f i n a n c i a l s u p p o r t for t h e project. A n y v i e w s e x p r e s s e d in it a r e t h o s e of t h e a u t h o r s a n d do n o t n e c e s s a r i l y c o n c u r w i t h t h o s e of W e l s h Office. REFERENCES Branson, J.R. and M.J. Pattenden, 1981. Multi element airborne dust measurements for the Borough of Walsall. AERE Harwell Report G1733 Rev. Cawse, P.A., 1974. A survey of atmospheric trace elements in the UK, 1972-73. AERE Harwell Report R7669. HMSO, London. Ellwood, P.C., 1986. Sources of lead in blood: a critical review. Sci. Total Environ., 52: 1-23. • McInnes, G., 1981. Multi-element and sulphate in particulate surveys: summary of fourth year's results (1979180). Rep. LR 408 (AP), Warren Springs Laboratory, Stevenage. NSEPB, 1985. Control of Toxic Substances in the Atmosphere: Cadmium. Rep. 3062, Natl. Swedish Environ. Protection Board, Solna.
71
T H E E F F E C T O F R E D U C I N G P E T R O L L E A D ON A I R B O R N E L E A D IN W A L E S , U.K.
R.A. PAGE
Welsh Office, Cathay's Park, Cardiff CF1 3NQ (United Kingdom) P.A. CAWSE and S.J. BAKER
AERE Harwell, Didcot, Oxon. (United Kingdom) (Received July 17th, 1987; accepted September 1st, 1987)
ABSTRACT Airborne lead has been measured at four urban, one semi-urban and one rural site in Wales during 1984, 1985 and 1986 to assess the effectof the reduction in lead additives in petrol which was required by an E C Directive at the beginning of 1986. The results showed a 52-61% fallin air lead in accord with the 6 3 % reduction in petrol lead.
INTRODUCTION
Concentrations of lead in air particulate were measured continuously during 1984, 1985 and 1986, at six sampling stations throughout Wales. Four of the sites are situated at urban locations at Queensferry (Clwyd); Wrexham (Clwyd); Bedwas (Mid Glamorgan); and at Velindre, near Port Talbot (West Glamorgan): a semi-urban sampling station is located at Trebanos (West Glamorgan). The rural 'background' is measured at Plynlimon (Powys). The objectives of this project are: (i) to record the decrease in lead concentrations in air which may occur in response to the reduced concentration of lead additives in petrol, which was required by EC Directive 85/210/EEC at the beginning of 1986; (ii) to conform with an EC Directive 82/844/EEC that requires measurement of urban lead levels in air to assess hazards to health; (iii) to compare the elevation in urban air concentrations of lead with levels at a rural location (Plynlimon) in central Wales. METHODS
OF SAMPLING
AND
ANALYSIS
The air particulate samplers consist of a plastic holder containing a cellulose filter (6 cm diameter, Whatman 40), through which air is drawn by a pump at a rate of about 61rain -1. The exact air flow rate is measured by a gas meter. The sampling equipment requires a mains electricity supply for its operation and has to be reasonably vandal-proof.
0048-9697/88/$03.50
© 1988 Elsevier Science Publishers B.V.,
Plynlimon, Powys Trebanos, W. Glam Queensferry, Clwyd Wrexham, Clwyd Bedwas, Mid Glare Port Talbot, W. Glam (Velindre)
Station
Non-urban Semi-urban Urban Urban Urban Urban
Site type
40 129 636 259 254 163 92 99 619 194 185 137
39 82 612 196 152 119
12 83 320 194 297 157
37 74 803 324 307 154
JanuaryMarch
OctoberDecember
January March
J u ly September
1985
1984 AprilJune
Quarterly concentrations (ng m-3) of lead in air near ground level
TABLE 1
19 61 546 158 158 125
AprilJune 18 77 618 153 222 158
J u ly September
19 111 614 261 210 145
OctoberDecember
15 40 248 85 89 73
JanuaryMarch
1986
17 37 282 99 74 69
AprilJune
15 39 290 93 47 59
July September
9 40 170 97 143 76
OctoberDecember
t~
73 TABLE 2 Mean concentrations of lead in air near ground level during 1964, 1985 and 1986 Station
Plynlimon, P o w y s Trebanos, W. G l a m Queensferry, Clwyd Wrexham, Clwyd Bedwas, Mid Glare Port Talbot, W. Glare (Velindre)
Site type
Non-urban Semi-urban Urban Urban Urban Urban
Mean conc. (ngm -3) 1984
1985
1986
% decrease in mean quarterly Pb conc. in 1986, relative to that during 1984/5
46 98 547 211 222 144
23 81 645 223 224 146
14 39 248 92 88 69
59 56 58 58 61 52
Sampling is continuous with the filters being changed monthly, with assistance from local E n v i r o n m e n t a l H e a l t h Departments. The filters collected during each 3 m o n t h period are bulked as follows to give four samples for each year. A q u a r t e r of each monthly sample is bulked and analysed for lead by X-ray fluorescence. The remainder of each m ont hl y sample is retained for any repeat measurements or f u r t h e r analyses of heavy metals t h a t may be required in the future: monthly samples can therefore still be analysed retrospectively if necessary, e.g. over winter periods of relatively high concentrations. RESULTS Lead in air Table 1 shows the qua r t er l y c o n c e n t r a t i o n s of lead (ngm -3) in air near ground level at the six sampling sites from 1984 to 1986. Generally, the annual average c o n c e n t r a t i o n remained fairly const ant at urban sites t h r o u g h o u t 1984 and 1985 (Table 2). However, lead concent rat i ons decreased at all urban and semi-urban sampling locations at the beginning of 1986 at which time the maximum permitted level for lead in petrol was reduced from 0.40 to 0.15 g 1-1 (Table 3). Lead in air at the four u r b a n sites is averaged for comparison (Fig. 1) with levels at the semi-urban and rural sampling stations. Considering the 2 years of measurements immediately before the decrease in lead, the highest annual average c o n c e n t r a t i o n of lead over the period 1984-85 was found at Queensferry (645 ng m -3) where the sampling site is near to a busy mo to r way and road junction. Compared with the rural 'background' levels at Plynlimon, the ur ba n lead concent rat i ons in 1984-85 show an order of magnitude increase but do not r e a c h more t h a n 32% of the limit set by the EEC ( 2 g g m -3) for control of danger to public health. It should be recognised t hat the data presented here are q u a r t e r l y mean values and it is possible t h a t mo n th ly air lead levels have at t ai ned higher values. At Plynlimon, the r ur al location, lead concent rat i ons decreased by 50% in 1985 compared with the previous year; this is not attributed to any decline in
74 TABLE 3 Lead in petrol Period
Maximum amount (g Pb/1 fuel)
Average amount (gPb/1 fuel)
1972 1 Apr 76-29 Nov 76 30 Nov 76-31 Dec 76 1 Jan 77-31 Dec 77 1 Jan 78-31 Dec 78 1 Jan 79-31 Dec 79 1 Jan 80-31 Dec 80 1 Jan 81-31 Mar 81 1 Jan 86-present time
0.84 0.55a 0.50b 0.50 0.45c 0.45 0.45 0.40d 0.15d
0.48 0.45 0.45 0.42 0.41 0.41 0.37
aNot a statutory requirement but required as part of British Standard 4040. bStatutory under Motor Fuel (Lead Content in Petrol) Regulations 1976. cStatutory under Motor Fuel (Lead Content in Petrol) Regulations 1976. dRequired by EEC regulations. lead in e x h a u s t emissions from m o t o r vehicles b u t r a t h e r to a decline in the c o n t r i b u t i o n from a n o t h e r source, n a m e l y coal b u r n i n g . The period of lower lead levels at P l y n l i m o n in 1985 does c o r r e s p o n d with the m i n e r s strike w h i c h c a u s e d a r e d u c t i o n in emissions from c o a l - b u r n i n g p o w e r stations. The h i s t o r i c a l i n f o r m a t i o n on lead in petrol in Table 3 shows t h a t a r e d u c t i o n o f 63% in lead additive o c c u r r e d on 1 J a n u a r y 1986. In L o n d o n over the first few m o n t h s of 1986, the lead-in-air c o n c e n t r a t i o n s were from 34 to 55% l o w e r t h a n in 1985 (New Scientist, 10 J u l y 1986, p. 21). Table 2 a n d Fig. 1 s h o w t h a t the p e r c e n t a g e decreases in m e a n q u a r t e r l y air c o n c e n t r a t i o n s of lead in 1986 were in the r a n g e 52-61% in Wales, w h i c h is c o n s i s t e n t with the r e d u c t i o n in petrol lead additive of 63%. It was to be expected t h a t the d e c r e a s e in 1986 w o u l d n o t a t t a i n 63% o w i n g to c o n t r i b u t i o n s from o t h e r s o u r c e s to the lead levels measured, e.g. coal b u r n i n g , m e t a l w o r k i n g a n d i n c i n e r a t i o n . As described above, a t P l y n l i m o n lead c o n c e n t r a t i o n s in 1985 were o n l y 50% of t h o s e r e c o r d e d in 1984, but, nevertheless, c o n c e n t r a t i o n s in 1986 still s h o w e d a d e c r e a s e in lead r e l a t i v e to 1985. I n 1972-1973, lead c o n c e n t r a t i o n s in air m e a s u r e d at P l y n l i m o n a n d T r e b a n o s were 52 and 1 8 5 n g m -a r e s p e c t i v e l y (Cawse, 1974), or 3 to 4-fold g r e a t e r t h a n in 1986.
Seasonal influence on atmospheric lead A t u r b a n a n d s e m i - u r b a n s a m p l i n g s t a t i o n s a s e a s o n a l influence is a p p a r e n t w i t h h i g h e r c o n c e n t r a t i o n s of lead in air d u r i n g some w i n t e r periods (Table 4). This s e a s o n a l effect c a n be explained to a l a r g e e x t e n t by r e d u c e d a t m o s p h e r i c dispersion u n d e r c o n d i t i o n s of p e r s i s t e n t low i n v e r s i o n layers t h a t c o m m o n l y o c c u r in w i n t e r m o n t h s and by i n c r e a s e d domestic h e a t i n g and p o w e r
$I
10
100
1984
- 46 (1984)
[
1985
~ i 23 (1985)
J
1986
~ : 14 (1986)
I 1121314J I 1994
= 98 (1984)
~ - 39 (1986)
I [213 i4i11219141 1999 1989
~ = 81 (1985)
TREBANOB (BEMI-URBAN)
Fig. 1. Quarterly concentrations of lead in air near ground level, 1984 to 1986.
(.,I
c v
o=
E QI
?
1000 -
PLYNLIMON ( N O N - U R B A N )
I
112131411 1904
- 281
J
1213[41 19es
~ = 310
J
125
s 12131 ages
~ :
U R B A N 81TE8 ( M E A N )
10
100
"~ 1 0 0 0
76 TABLE 4 Ratios o f ' w i n t e r ' and 'summer' concentrations of lead in air near ground level during 1984 and 1985 Station
Conc. of Pb in ~winter' Conc. of Pb in ~summer'
Plynlimon, Powys Trebanos, W. Glam Queensferry, Clwyd Wrexham, Clwyd Bedwas, Mid Glam Port Talbot, W. Glam (Velindre)
1984
1985
1986
0.40 1.2 0.78 1.2 1.6 1.3
1.5 1.3 1.2 1.9 1.4 1.1
0.75 1.1 0.73 0.97 1.9 1.2
'winter' period includes ( J a n u a r y to March) and (October to December) quarters. 'summer' period includes (April to June) and (July to September) quarters. TABLE 5 Ratios of u r b a n / r u r a l air concentrations of lead Station
Year
Mean a n n u a l conc. of Pb at u r b a n site Mean a n n u a l conc. of Pb at Plynlimon
Trebanos
1984 1985 1986 1984 1985 1986 1984 1985 1986 1984 1985 1986 1984 1985 1986
2.1 3.5 2.8 3.1 6.3 4.9 4.6 9.7 6.6 4.8 9.7 6.3 12.0 28.0 18.0
Velindre
Wrexham
Bedwas
Queensferry
consumption, particularly in coal burning areas such as Bedwas, which shows consistently elevated levels of lead in air during all three winters.
Increases in lead from urban activity Table 5 lists ratios of the annual average concentrations of lead in air observed at the urban sites to the rural 'background' at Plynlimon. Lead concentrations in air at Queensferry in 1985 were almost 30 times greater than
77 a t P l y n l i m o n d u r i n g t h e c o r r e s p o n d i n g s a m p l i n g period, a n d b e t w e e n 2-fold a n d 10-fold i n c r e a s e s in c o n c e n t r a t i o n s a b o v e t h e P l y n l i m o n ' b a c k g r o u n d ' w e r e o b s e r v e d a t t h e o t h e r u r b a n sites. T h e s e e l e v a t i o n s a r e a t t r i b u t e d to v e h i c l e e x h a u s t emissions. CONCLUSIONS T h e p r e s e n t s t u d y h a s s h o w n t h a t t h e r e c e n t d e c r e a s e in lead c o n c e n t r a t i o n s in p e t r o l h a s r e s u l t e d in a fall of 52-61% in a i r lead m e a s u r e d a t u r b a n a n d s e m i - u r b a n l o c a t i o n s in W a l e s in a c c o r d w i t h t h e 63% r e d u c t i o n in p e t r o l lead w h i c h o c c u r r e d a t t h e b e g i n n i n g of 1986. I t will be i n t e r e s t i n g to see w h e t h e r b l o o d lead c o n c e n t r a t i o n s of u r b a n p o p u l a t i o n s fall in s y m p a t h y w i t h t h i s identified r e d u c t i o n in a i r lead c o n c e n t r a t i o n s . ACKNOWLEDGEMENTS T h e a u t h o r s w o u l d like to t h a n k t h e E n v i r o n m e n t a l H e a l t h D e p a r t m e n t s of e a c h of t h e L o c a l A u t h o r i t i e s i n v o l v e d for t h e i r a s s i s t a n c e w i t h s a m p l i n g o p e r a t i o n s . T h i s p a p e r w a s w r i t t e n a n d p u b l i s h e d w i t h t h e a g r e e m e n t of W e l s h Office w h i c h p r o v i d e d f i n a n c i a l s u p p o r t for t h e project. A n y v i e w s e x p r e s s e d in it a r e t h o s e of t h e a u t h o r s a n d do n o t n e c e s s a r i l y c o n c u r w i t h t h o s e of W e l s h Office. REFERENCES Branson, J.R. and M.J. Pattenden, 1981. Multi element airborne dust measurements for the Borough of Walsall. AERE Harwell Report G1733 Rev. Cawse, P.A., 1974. A survey of atmospheric trace elements in the UK, 1972-73. AERE Harwell Report R7669. HMSO, London. Ellwood, P.C., 1986. Sources of lead in blood: a critical review. Sci. Total Environ., 52: 1-23. • McInnes, G., 1981. Multi-element and sulphate in particulate surveys: summary of fourth year's results (1979180). Rep. LR 408 (AP), Warren Springs Laboratory, Stevenage. NSEPB, 1985. Control of Toxic Substances in the Atmosphere: Cadmium. Rep. 3062, Natl. Swedish Environ. Protection Board, Solna.