Why Air Pollution?
In recent years, air pollution and its impact on people’s health has become a significant issue on the global health agenda. Nine out of ten people worldwide breathe polluted air, which disproportionately affects those living in low-resource settings. Air pollution is a major contributor to the global burden of disease, with an estimated 9% of all deaths in 2017* attributable to outdoor and household** air pollution. While the impacts of air pollution on respiratory diseases is widely recognized and immediately understood, 40% of the estimated 4.9 million deaths attributable to air pollution in 2017 are due to cardiovascular diseases.
Air pollution is a complex and dynamic mixture of numerous compounds in gaseous and particle form, originating from diverse sources, subject to atmospheric transformation and varying over space and time. Three common air pollutants, particulate matter (PM), ozone and nitrogen dioxide (NO2), are the focus of most monitoring programs, communication efforts, health impact assessments, and regulatory efforts.
Evidence for impacts on cardiovascular disease is most consistent for particulate matter, which is responsible for the vast majority of the disease burden via its impacts on ischemic heart disease, and stroke, as well as lung cancer, COPD, lower respiratory infections, Type 2 diabetes, pregnancy outcomes and related infant mortality. Ozone is mainly associated with exacerbation of respiratory disease, with COPD incidence and mortality and with metabolic effects. NO2 is often used as an indicator of traffic-related air pollution. Chronic exposure to NO2 is associated with incident childhood asthma while short-term variability is associated with exacerbation of asthma and increased daily mortality counts.
* While other estimates exist and each have their uncertainties, all estimates of attributable disease burden are large and high-ranking in comparison to traditional and more widely recognized CVD risk factors.
** Household air pollution is mainly a concern in low income countries where polluting fuels (coal, wood, agricultural residue, animal dung) are used for cooking and heating.