Health Risk Assessment of Air Pollution and the Impact of the New WHO Guidelines
Air pollution is a major cause of premature death and disease and is the single largest environmental health risk in Europe. Heart disease and stroke are the most common reasons for premature deaths attributable to air pollution, followed by lung diseases and lung cancer.
The health risk assessment methodology assumptions have been recently adapted to follow the recommendations by the World Health Organisation (WHO), released in 2021. The new global air quality guidelines by WHO provide up-to-date health-based guideline levels for major health-damaging air pollutants and new recommendations for assessing the risk of exposure to air pollution.
This report estimates the health risk related to air pollution in 2020 based on the latest methodology. The estimates consider the number of premature deaths and years of life lost related to exposure to fine particulate matter, ozone and nitrogen dioxide, both for the 27 Member States of the European Union and for additional 14 European countries (Albania, Andorra, Bosnia and Herzegovina, Iceland, Kosovo, Liechtenstein, Monaco, Montenegro, North Macedonia, Norway, San Marino, Serbia, Switzerland, and Türkiye).
A sensitivity analysis to the changes in concentration-response functions and counterfactual concentrations is performed to understand the impact of such changes on the mortality outcome estimates. The sensitivity analysis included both old and new health risk methodology assumptions but also the recommendation from the ELAPSE study on the concentration response functions. The ELAPSE project includes some of the most recent studies on the health effects at low air pollution levels by examining associations between exposures to relatively low levels of air pollution across Europe, including levels below the current EU standards.
The results for 2020 show that the largest health risks are estimated for the countries with the largest populations. However, in relative terms, when considering e.g., years of life lost per 100 000 inhabitants, the largest relative risks are observed in central and eastern European countries for PM2.5, in central and southern European countries for NO2, and south and eastern European for O3. The lowest impact is found for the northern and north-western parts of Europe, where the concentrations are lowest. The number of premature deaths attributed to air pollution in 2020 compared to 2019, increased for PM2.5 and decreased for NO2 and O3. Apart from the changes in concentrations and demographics, the COVID-19 pandemics seems to also have an influence on these changes. For PM2.5, the reduction in concentrations were counteracted by the excess of deaths due to the pandemics. In the case of NO2, the reduction in concentrations was more pronounced as a result of the lockdown measures and the drastic reduction in traffic and its impact in reducing mortality was bigger than the increasing impact of excess of deaths due to COVID-19.
Changing assumptions on concentration-response functions and counterfactual concentrations have implications for estimating mortality health outcomes. The sensitivity analysis shows that it is not straightforward to assess which assumptions estimates the highest health impacts when both factors change. In this case, the final outcome will depend on the concentration at the grid-cell level. The latest assumptions are expected to reduce the health outcomes for PM2.5 and increase for NO2 and O3, when compared to the previous one. When aggregated to all countries, the health outcomes are reduced by over 40 % for PM2.5 and increased by 50 % and 30 % for NO2 and O3, respectively, in 2020. However, this change varies across countries depending on the concentration level the population in the individual countries is exposed to.