What does calculating impacts of specific morbidity outcomes add to perceptions of air pollution health impact assessment?

Abstract

Introduction: Health impact assessments often use broad categories of outcomes, e.g. all respiratory or all cardiovascular admissions. This minimises diagnostic misclassification but does not fully communicate the evidence on associations between air pollution and specific diseases. More specific health impact calculations may resonate with the public more than severe but rarer outcomes.Methods: Literature searches were done for meta-analyses pooling evidence on a variety of pollutants (PM10, PM2.5, NO2 and O3) and 40 health outcomes. We investigated the effects of short- and long-term exposure to pollution and did final calculations on 17 morbidity outcomes, rejecting those with weaker evidence, lack of baseline rates, and no priority from focus groups. The selected concentration-response functions were combined with monitoring site, baseline rate/cases and population (e.g. beside roads) data to calculate health impacts in up to 4 scenarios (roadside vs background (daily and annual); 75th vs 25th percentile daily average and a 20% reduction in annual average) across 9 UK and 4 Polish cities. The largest result per pollutant was given rather than summing across pollutants.Results: The largest change in number of cases was for children with low lung function in London (7927 for a 20% reduction in NO2). Changes in cases of acute bronchitis in children in London were also high (3683 for a 20% reduction in PM10). Warsaw had greater impacts on cardiovascular than respiratory endpoints compared with London. Other example statements include ‘living near busy roads in Oxford may stunt lung growth in children by 14%’ and ‘in London on higher pollution days, 142 more children with asthma experience symptoms than on lower pollution days’.Conclusions: Health impact statements for a wider variety of outcomes may aid communication of the importance of different health effects to policymakers and the public.