Quantification of the effects of air pollution on health in the United Kingdom / Department of Health, Committee on the Medical Effects of Air Pollutants.

  • Great Britain. Committee on the Medical Effects of Air Pollutants
Date:
[1998]
Catalogue details

Licence: Open Government Licence

Credit: Quantification of the effects of air pollution on health in the United Kingdom / Department of Health, Committee on the Medical Effects of Air Pollutants. Source: Wellcome Collection.

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    4.10 A number of workers have followed up groups of persons, usually with known respiratory disease, to see whether fluctuations in pollution levels are reflected in variations in daily symptoms or lung function indices. For example, in a panel of 73 Dutch children with chronic respiratory symptoms, SO, was associated positively with wheeze and bronchodilator use and negatively with peak expiratory flow rates.'° This was attributable to an episode in which 24-hour average SO, concentrations rose to 105 wg/m* and PM, exceeded 105 wg/m*. A British study of 75 adults with chronic respiratory disease showed similar associations, although the SO, levels did not breach WHO guidelines during the course of the study.'' Other examples are listed by Lebowitz.* These findings ones the impression that fairly small changes in SO, levels can have a range of effects upon health which are not confined to bringing forward ‘the deaths of seriously ill individuals, although it is difficult to separate the effects of SO, and particulates in some of these studies. differing average concentrations of SO,. There are a number of problems associated with such studies of chronic effects of air pollutants: these have been discussed in Chapter 2, paragraph 2.28. Mortality 4.12 Geographical studies relating death rates to exposure levels have suggested that an association exists which does not seem to be entirely explained by the obvious confounding variables.° A study in different regions of the Czech Republic found a strong association between SO, exposure and the respiratory mortality of infants aged one month to one year; number of deaths between areas with the highest and lowest quintiles of exposure (annual geometric means > 57.9 and < 12.5 wg/m’, respectively) differed by a factor of 5.41 after adjusting for socio-economic variables, and by 3.91 when particulate and NO, levels were allowed for.'* There was also a relationship with particulate exposure, and it may prove to be impossible to separate the effects of these pollutants, since they tend to be associated with each other. Quantifying the effect is also very difficult; the Department of Health’s Advisory Group on the Medical Aspects of Air Pollution Episodes’’ was not able to address the question of exposure-response on the basis of existing data, although there was evidence of a qualitative relationship. 4.13 A Japanese study of two areas partly circumvented the problem of confounding because one area showed first a worsening and then an improvement in air pollution over a period of 21 years.* As air pollution deteriorated, mortality due to asthma and chronic bronchitis increased; when air quality improved, asthma mortality decreased immediately and chronic bronchitis mortality declined gradually, reaching the level in the unpolluted area 4-5 years after SO, concentrations began to satisfy air quality standards. Symptoms and lung function 4.14 Inrelation to symptoms, the Department of Health Advisory Group” arrived at a “qualified judgement about exposure-response” on the basis of selected studies as follows. An annual mean concentration of 24-hour mean SO, of 60-140 g/m? is associated with increased respiratory symptoms in adults. At 140-200 wg/m?* associations have been reported with increased respiratory illnesses in children. There are no clear indications of a threshold level. Some of the relevant studies did not control for environmental tobacco smoke. 4.15 Lebowitz* notes the association between SO, and the prevalence of chronic obstructive pulmonary disease (COPD); he estimates a relative risk for COPD of 1.5-2.5 as the annual SO, and TSP concentrations concurrently exceed 100 g/m’.
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