Photo: Tina Leggio/ BY-NC-ND

Ozone causes one million premature deaths

Because ozone is transported over long distances, action to reduce ozone precursor pollutants is needed at local, national, regional and global scales.

According to a new study by the Stockholm Environment Institute (SEI), long-term exposure to ozone air pollution contributed to about one million premature respiratory deaths globally – or approximately one in five of all respiratory deaths in 2010. This figure is more than twice as high as previous estimates of the global health impacts of ozone.

Findings from the study were based on results from a recent US analysis of the association of long-term ozone exposure and respiratory mortality in 670,000 adults, which is a substantially larger number of included study participants and observed deaths than an earlier estimate published in 2009, on which previous global ozone health impact calculations have been based.

The largest contribution to global ozone-attributable respiratory deaths was from Asia, which accounted for about 79 per cent of the total. India accounted for about 400,000, and China for about another 270,000. Africa, Europe and North America each had between 50,000 and 60,000 ozone-attributable deaths, with fewer in Latin America and Oceania.

“There is a degree of uncertainty in these estimates because the concentration-response function we used is based on analysis from the United States,” said Chris Malley, lead author of the study and SEI researcher at the University of York. “We don’t know whether the relationship is the same in other regions, such as in India and China, where the prevalence of other risk factors for respiratory diseases varies considerably. We also estimated people’s ozone exposure using a global atmospheric chemistry transport model, which means that we could not account for differences in ozone exposure at small geographic scales.”

Ozone is not directly emitted but is formed in the atmosphere from emissions of pollutants like nitrogen oxides (from vehicles and other types of combustion), volatile organic compounds (from solvent use and fuel combustion), and methane (from agriculture, waste treatment, and fossil fuel extraction and distribution). Once formed, ozone can stay in the atmosphere for a few weeks and travel long distances from the emission sources, across countries and continents.

“To reduce ozone pollution, you need to control emissions of different precursors from many different sources,” SEI’s Policy Director Johan C.I. Kuylenstierna, co-author of the study said. “This includes emissions from road transport, household energy use, as well as methane emissions from agriculture.”

“It is important to realize that action needs to be taken on all the major sources,” Kuylenstierna added. “The long-range transport of ozone means that to reduce ozone, action is needed on local, national, regional and global scales. That means that regional cooperation often is needed to solve the problem.”

Source: SEI press release 28 August 2017. Link:


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