Study shows increase in respiratory deaths from climate change

In a study published in 2012, researchers modelled changes in air quality during the ‘industrial period’, defined here as the years between 1860 and 2000, and linked these changes to premature human deaths. They considered three main drivers of air pollution: 1) short-lived air pollutants (such as sulphate and various carbon aerosols) emitted from human activities and biomass burning; 2) climate change and 3) increasing methane concentrations (e.g. from energy production and distribution, agriculture); and assessed how changes in each of these factors influenced changes in concentrations of O3 and fine particulate matter (PM2.5).

To estimate the effects of air pollution on human health, the researchers used data from long-term epidemiological studies from the American Cancer Society conducted in the United States, under the assumption that they are relevant worldwide. From 1860 to 2000, total PM2.5 and health-relevant ozone concentrations were estimated to have increased worldwide by approximately 8 μgm−3 (micrograms per cubic metre of air) and 30 ppbv (parts of O3 per billion parts of atmosphere) respectively. Globally, increased industrial PM2.5 pollution (from all three drivers of air pollution considered in the study) was estimated to be responsible for around 1.53 million premature deaths from cardiopulmonary disease and 95,000 premature deaths from lung cancer each year. Increased industrial surface O3 was responsible for around 0.4 million early deaths from respiratory diseases each year.

Increased emissions of short-lived pollutants alone, accounted for 94% of the total change in PM2.5 levels, and this is reflected in the 1.49 million avoidable early deaths from cardiopulmonary disease and the 92,000 early deaths from lung cancer from exposure to higher levels of PM2.5. Greater emissions of short-lived pollutants also accounted for 83% of the total increase in surface O3 during the period, and was associated with 0.33 million (or about 85% of the total 0.4 million) early deaths caused by this pollutant.

Climate change also affected air quality by increasing concentrations of PM2.5 by approximately 0.4 μgm−3, which accounts for 5% of the overall increase in PM2.5 concentrations. Climate-related increased exposure to PM2.5 was associated with 91,000 early deaths from cardiopulmonary disease and 5,000 early deaths from lung cancer. In addition, climate change was found to increase the concentration of surface O3 by about 0.5ppbv, which is less than 2% of the total changes in surface O3 levels. These ozone changes were related to 7,000 early deaths from respiratory diseases. Increased concentrations of methane during the industrial period have been highly influential on atmospheric chemistry and have contributed to increases in O3 concentrations of 4.3 ppbv, or about 15% of the total increase in O3 levels during this time. Methane increases resulted in only tiny changes in PM2.5 levels (0.04 μgm−3). Increased methane concentrations consequently had an insignificant effect on early deaths associated with PM2.5 exposure, but caused about 50,000 early deaths from respiratory diseases related to exposure to O3.

Methane changes have significantly contributed to increased surface O3 pollution during the industrial period. As methane is an O3 precursor and global methane concentrations are expected to keep rising, early deaths associated with surface O3 pollution from methane are also likely to increase, suggesting that efforts to lower methane levels will not only slow the rate of climate change but will improve air quality and provide health benefits globally.

CRS Head of Environment, Richard Ball commented ‘this long term study shows the impact of climate change not on a global or regional scale, but on individuals lives. Carbon Management is not just about Doing the Right Thing, and saving money, it has affects; just as serious as the release of toxic chemicals.’

Source: Fang, Y., Naik, V. Horowitz, L. W., and Mauzerall, D. L. (2012) Air pollution and associated human mortality: the role of air pollutant emissions, climate change and methane concentration increases during the industrial period. Atmospheric Chemistry and Physics Discussions. 12: 22713-22756. Doi:10.5194/acpd-12-22713-2012. This study is free to view at: www.atmos-chem-phys-discuss.net/12/22713/2012/acpd-12-