Lectures and seminars

Health impact assessment of air pollution – An annotated history

2017-05-1014:00 Lecture Hall Petrén, Nobels väg 12BCampus Solna

Speaker: Francesco Forastiere, Department of Epidemiology, Lazio Regional Health Service, ASL Roma 1, Rome, Italy

Epidemiologic evidence provides a basis for air pollution health impact assessment in the form of exposure-response functions (ERFs), that e.g. quantify the increase in the risks of mortality related to different levels of ambient air pollution.  These functions are essential to quantify the burden of disease attributable to air pollution or in scenarios evaluations for policy decisions.

There are several applications of impact assessment at global, national and local levels and they vary with regards to the scope (burden of diseases or scenario analysis), the ERFs applied, the estimation of current exposure and the counterfactual (cut-off) values below which the health impact is not predicted. I will present and discuss recent efforts reported e.g. by WHO (HRAPIE project, 2013) and by the Global Burden of Disease (GBD) project. The applications have evolved over time resulting in different estimates of the burden of disease.

Given the importance of the underlying assumptions to health impact estimation, normative and policy evaluation activities, the development of stable exposure-response functions is key. 

Abstract: 

Epidemiologic evidence provides a reliable basis for air pollution impact assessment.  This evidence is summarized in the form of exposure-response functions (ERFs) that quantify the increase in the risks of mortality related to exposure to different levels of ambient air pollution.  These functions are essential to quantify the burden of disease attributable to air pollution or in scenarios evaluations for policy decisions.

There are several applications of impact assessment at global, national and local levels and they vary with regards to the scope (burden of diseases or scenario analysis), the ERFs applied, the estimation of current exposure and the counterfactual (cut-off) values below which the health impact is not predicted. A WHO Regional Office for Europe document (HRAPIE project, 2013) provided rationale and indications in order to perform health impact assessment of air pollution (in the context of cost-benefit analysis of policies at European level) based on linear or log-linear functions relating particulate matter of a diameter less than 2.5 µm (PM2.5) to natural mortality and other specific causes.  In this report, the meta-analysis by Hoek (2013) (based on 11 studies) provided the ERF for the PM2.5-all-cause (or natural-cause) mortality association (6%, 95% Confidence Interval, CI = 4-8.3% per 10 µg/m3 PM2.5). 

The Global Burden of Disease (GBD) project developed integrated exposure -response functions (IERs) that combined evidence from studies of ambient air pollution, second-hand smoke, household air pollution and active smoking to estimate risk for ambient air pollution over the entire global range of particulate matter exposure. The IER provides an excellent approach to estimate mortality attributable to PM2.5 for selected causes of death (ischemic heart diseases, stroke, COPD and acute respiratory infections) over the entire global range of exposure to PM2.5, and it was used by WHO to estimate the burden of disease attributable to ambient air pollution for the year 2012 in 2014 and 2016 (WHO 2014a, 2016c).

However, because applications have evolved over time resulting in different estimates of the burden of disease it is considered important to understand the changes over time. Consideration of these changes is especially essential because these estimates have received wide attention in professional journal articles, news coverage, lay press and political discussions around the globe. 

All approaches depend on the underlying assumptions and have strengths and limitations that require appreciations and evaluations of the potential consequences. There is certainly the need to assess the full range of air pollution concentrations around the globe and to provide a method to be applicable in all countries. Furthermore, the debate on the primary health outcomes needs careful consideration.  Given the importance of the underlying assumptions to health impact estimation, normative and policy evaluation activities, the development of stable exposure-response functions is key.