Health science and policy summaries- advanced draft

Accelerating action for clean air, clean energy accessand climate change mitigation Conference discussion papers to support WHO's Second Global Conferenceon Air Pollution and Health This is an advance proof and should be cited as such in media or other reports. Acknowledgments The production of this report was supported by funds generously provided by Foreign,Commonwealth andDevelopment Office ofthe Government of the United Kingdom of Great Britainand Northern Ireland, the Spanish Agency for International Development Cooperation and theMinistry of Foreign Affairs, European Union, and Cooperation of the Government of Spain, theNorwegian Agency for Development Cooperation, the Government of the Netherlands and theClean Air Fund. WHO Air Quality, Energy and Health Science and PolicySummariesHealth effects of air pollution – evidence and implicationsTechnical brief Key messages The health effects of air pollution have been documented and described by the medical communityfor several decades.Air pollution can reach almost all organs and systems of the body, impacting respiratory,cardiovascular, cerebrovascular, reproductive and metabolic systems, amongst others.Children, pregnant women, older people, people living with chronic disease, and those living in thelowest socioeconomic groups are most at risk.Air pollution is the leading environmental health risk factor causing about 6.4 million deathsglobally every year.Close to 84% of air pollution related deaths are from noncommunicable diseases (NCDs), includingheart disease, stroke, chronic obstructive pulmonary disease (COPD) and lung cancer.Air pollution burden remains underestimated and is likely to increase, due to population ageing andemerging links with additional diseases and conditions (e.g. low birth weight, neurological andpsychiatric diseases, metabolic diseases, cancer other than lung).There are substantial inequalities in air pollution levels and health burden globally, closelyinterlinked with social and economic disparities.Ensuring health data are available, reliable and that air pollution exposure is linked with relevanthealth outcomes using available coding for recording, reporting and monitoring diseases is criticalfor disease surveillance, impact assessment and prioritization of interventions.With the enormous health evidence at hand, we must act now to ensure clean air for all and speedup actions for those who are most affected and most vulnerable. Overview Health effects of air pollution – a long history Evidence on air pollution effects on health has been well documented over the last six decades.Important milestones over the years are marked by key epidemiological studies, the first World HealthOrganization (WHO) reports in the 1950s(1),and the publication of the first edition of the WHOglobal air quality guidelines in 1987(2),which provided recommendations for thresholds of airpollutants safe for health. Over the last 40 years, significant statements have been made by medicalsocieties on the definition of what constitutes an adverse health effect of air pollution, which haveevolved with mounting scientific evidence from toxicology and epidemiology(3,4)(Fig. 1). Notes:ATS: American Thoracic Society; ERS: European Respiratory Society; IARC: International Agency forResearch on Cancer. Air pollution exposure pathways and physiological impacts While the WHO air quality guidelines series cover a wide range of air pollutants, this summary willfocus on the health effects of a subset of pollutants. Particulate matter (PM) is a good indicator of airpollution as it arises from multiple sources, and it is ubiquitous in our environment. PM consists of acomplex mixture of solid particles and liquid droplets of varying size, shape and composition. It is thepollutant for which there is the largest body of evidence on health impacts. Other main air pollution are nitrogen dioxide and ground-level ozone, which are gases that originatefrom various sources and lead to substantial adverse health impacts, though not comparable inmagnitude with PM(5). See SPS1:Exposure to health damaging air pollutants While inhalation is the main pathway of exposure to air pollutants, there are other routes of humanexposure, such as dermal absorption, ocular exposure and ingestion. When inhaled, health-damaging pollutants including small particulates can penetrate deep into therespiratory system and enter the blood stream, allowing them to reach almost all organs within thebody (Fig. 2), including but not limited to cardiovascular, reproductive and metabolic systems, brain,liver and kidneys. Many of these damaging effects on the cells and tissues within the human body maynot be reversible. Furthermore, air pollution causes oxidative stress, inflammation, immune response,DNA problems, skin damage and direct damage to parts of the body like eyes, nose, throat, lungs, gut,neurons, bones and blood cells. Short- and long-term exposure to air pollutants and