Health effects of exposures to mixtures of air pollutants / Advisory Group on the Medical Aspect of Air Pollution Episodes.

  • Great Britain. Advisory Group on the Medical Aspects of Air Pollution Episodes
Date:
1995
Catalogue details

Licence: Open Government Licence

Credit: Health effects of exposures to mixtures of air pollutants / Advisory Group on the Medical Aspect of Air Pollution Episodes. Source: Wellcome Collection.

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    Figure 3.3 Correlation, during the months of June to August in the years 1993 and 1994, of the daily mean concentration of PM, 9 (ug/m>) with the daily maximum hourly concentration of O3 (ppb) at London, Bloomsbury site. Individual values are plotted with the regression line with 95% confidence limits. Equation of the line is [03] = 0.897[PM 9] + 4.66, correlation coefficient (r) = 0.658. ) = [e) oO 80 60 40 20 Daily maximum O, concentration (ppb 0 20 40 60 80 100 Daily average PM,, concentration (g/m°) 3.20 It is interesting to note that data from a long-running rural monitoring site with co-located O3 and aerosol measurements indicates some correlation between O, and total aerosol acidity (H*), but not with total sulphate ion (SO,2°) or nitrate ion (NO3, data not shown). This relationship appears, however, to be seasonally dependent (see Table 3.6). 3.21 It is readily apparent that the strongest observed pollutant ‘cluster’ in Figure 3.2a is that between carbon monoxide (CO), nitrogen dioxide (NO,), oxides of nitrogen (NOy) and particulate matter (PM,,). This is clearly due to motor vehicle emissions, which are the most important source of these pollutants in UK urban environments. Table 3.6 Correlations between sulphate ion, acid aerosol*, and ozone at Harwell (1983-1991) Pollutant measures Time of year Correlation coefficient (r ) Significance (p) SO* vs maximum hourly O, of day All months 0.068 0.524 March - June 0.073 0.68 | September - December —0.144 0.484 SO,° vs mean hourly O, of day All months —0.002 0.987 March - June —0.030 0.868 September - December —0.142 0.488 H* vs maximum hourly O, of day All months 0.378 0.011 March - June 0.486 0.078 September - December 0.017 0.953 Ht vs mean hourly O, of day All months 0.194 0.208 March - June —0.053 0.856 September - December —0.615 0.019 * Calculated value derived from ion balance 3.22 The vehicle emissions cluster may be further investigated within the urban background sites as a whole by calculating mean co-located pollutant concentrations during episodes with hourly NO, concentrations exceeding 100 ppb (188 pg/m3), see Table 3.7. The 100 ppb figure used here corresponds to the lower limit of the DoE ‘Poor’ air quality band and is similar to the EC Directive 98th percentile, of hourly means, limit value (104.6 ppb, 200 ug/m3) for this pollutant. Whilst Figure 3.2a, not surprisingly, shows elevated concentrations of CO and PM, , during such periods, sulphur dioxide (SO;) levels also appear to be elevated. During 63 such episodes recorded by the urban