According to a study carried out by a team of researchers headed by Johannes Lelieveld, Max Planck Institute for Chemistry in Mainz, Germany, every year 3.3 million people die prematurely from the effects of air pollution worldwide; predominantly in Asia and mostly by PM2.5. This figure could double by 2050 if emissions continue to rise at the current rate. Surprisingly, the largest sources of air pollution are not industry and transport but small domestic fires and agriculture.
The team used a global atmospheric chemistry model to investigate the link between premature mortality and seven emission source categories in urban and rural areas. Emission sources include industry, transport, agriculture, fossil fuel-fired power plants, domestic energy use, such as diesel generators, small stoves, and smoky open wood fires, which many people in Asia use for heating and cooking.
According to epidemiological studies, fine particulate matter leads to cerebrovascular, heart and pulmonary diseases, and lung cancer.
Much of the smog in India and China is caused by small domestic fires. These are low-key activities which add up, particularly if the majority of the population uses them. Overall, one-third of premature deaths worldwide are attributable to this inefficient form of combustion.
A leading cause of air pollution in Europe, Russia, Turkey, Japan and the eastern United States is agriculture. Ammonia enters the atmosphere as a result of the use of fertilizers and intensive livestock farming. It then undergoes a number of reactions to form ammonium sulphate and ammonium nitrate. These substances are a major factor in the formation of small airborne particles (PM2.5). In some countries, for example, in the Ukraine, Russia and Germany, agriculture is the cause of over 40 % of all deaths due to air pollution.
Other major sources are fossil-fuel fired power plants, industry, biomass combustion, and motor vehicles. Just under a fifth of premature deaths are attributed to natural dust sources, particularly desert dust in North Africa and the Middle East.
- The contribution of outdoor air pollution sources to premature mortality on a global scale,
J. Lelieveld, J. S. Evans, M. Fnais, D. Giannadaki, A. Pozzer,N
Nature 2015, 525, 367–371.