Using epidemiology to estimate the impact and burden of exposure to air pollutants

Abstract

This paper focuses on the use of results of epidemiological studies to quantify the effects on health, particularly on mortality, of long-term exposure to air pollutants. It introduces health impact assessment methods, used to predict the benefits that can be expected from implementation of interventions to reduce emissions of pollutants. It also explains the estimation of annual mortality burdens attributable to current levels of pollution. Burden estimates are intended to meet the need to communicate the size of the effect of air pollution on public health to policy makers and others. The implications, for the interpretation of the estimates, of the assumptions and approximations underlying the methods are discussed. The paper starts with quantification based on results obtained from studies of the association of mortality risk with long-term average concentrations of particulate air pollution. It then tackles the additional methodological considerations that need to be addressed when also considering the mortality effects of other pollutants such as nitrogen dioxide (NO₂). Finally, approaches that could be used to integrate morbidity and mortality endpoints in the same assessment are touched upon. This article is part of a discussion meeting issue 'Air quality, past present and future'.

Keywords: health impact assessment; morbidity; mortality burden; nitrogen dioxide; particulate air pollution; two-pollutant models.

Figure 1.

Fraction of mortality attributable to long-term exposure to particulate air pollution by Local Authority area in England (and key). Taken from Public Health England's (PHE) Public Health Outcomes Framework (PHOF) datatool [17]. Contains public sector information licensed under the Open Government Licence v3.0. (Online version in colour.)

Figure 2.

HRs (95% CI) per 10 μg m⁻³ for cohort studies reporting associations between NO₂ and all-cause mortality. (From COMEAP, 2018) [19].

Figure 3.

Illustration of model integrating morbidity and mortality. (1) and (2): RRs taken from the literature. (3): Derived from RR for all-cause mortality (1.06 per 10 µg m⁻³) and (2).