Air pollution kills 2 million a year
More than two million deaths around the world each year are a direct result of outdoor air pollution caused by humans, according to a study published in Environmental Research Letters. The researchers found, however, that climate change has a minimal effect on exacerbating air pollution, and accounts directly for only a small proportion of those deaths.
The scientists estimated that about 470,000 people die each year because of human-caused increases in ozone. They also concluded that 2.1 million deaths annually are caused by increases in fine particulate matter, which are small particles suspended in the air that can penetrate deep into the lungs and cause cancer and other respiratory illness. Many of these deaths occur in East Asia and South Asia, because of large populations and severe air pollution in those areas.
For the study, researchers used 14 climate models to simulate the concentration of ozone, and six models to simulate the levels of fine particulate matter in the years 2000 and 1850. Then previous epidemiological studies were used to assess how the specific concentrations of air pollution related to current mortality
The research suggested that only a small number of the deaths could be directly attributed to the effect of climate change on air pollution—roughly 1,500 deaths due to ozone and 2,200 deaths due to fine particulate matter each year. Climate change affects air quality in many ways, possibly leading to local increases or decreases in air pollution. For instance, temperature and humidity can change the reaction rates which determine the formation or lifetime of a pollutant, and rainfall can determine the time that pollutants can accumulate. Higher temperatures can also increase the emissions of organic compounds from trees, which can then react in the atmosphere to form ozone and particulate matter.