People living in low- and middle-income countries disproportionately bear the burden of outdoor air pollution: 91% of the 4.2 million premature deaths from this cause occur in low- and middle-income countries, primarily from the WHO South-East Asia and Western Pacific Regions. The latest estimates of the burden of disease reflect the critical role that air pollution plays in cardiovascular disease and related mortality. There is growing evidence showing links between ambient air pollution and cardiovascular disease risk, including some studies conducted in heavily polluted areas.

The WHO estimates that approximately 58% of premature deaths related to air pollution that occurred in 2016 were due to ischemic heart disease and stroke, while 18% of deaths were due to chronic obstructive lung diseases and acute respiratory infections , and 6% of the deaths were due to lung cancer.

Some deaths can be attributed to more than one risk factor. For example, both tobacco use and ambient air pollution can lead to lung cancer. Some of the lung cancer deaths could have been prevented by improving ambient air quality or reducing tobacco use. An evaluation by the WHO International Agency for Research on Cancer, carried out in 2013, determined that outdoor air pollution is carcinogenic to humans, and that particulate matter in polluted air is closely related to the increasing incidence of the cancer, especially lung cancer. A relationship has also been observed between outdoor air pollution and an increase in urinary tract and bladder cancer.

Addressing all risk factors for noncommunicable diseases (including air pollution) is critical to protecting public health. Most sources of outdoor air pollution are beyond the control of people, and require the adoption of measures by cities, as well as national and international regulatory bodies in sectors such as transport, management of energy waste, construction and agriculture.

There are numerous examples of policies in the transport, urban planning, electricity generation, and industrial sectors that have done well in reducing air pollution:

Industry: use of clean technologies that reduce emissions from industrial chimneys; improved urban and agricultural waste management, including recovery of methane gas from landfills as an alternative to incineration (for use as biogas).

Energy: ensure access to affordable clean domestic energy solutions for cooking, heating and lighting.

Transportation: adoption of clean electricity generation methods; prioritization of rapid urban transport, pedestrian paths and bicycle lanes in cities, as well as interurban transport of cargo and passengers by rail; use of cleaner heavy duty diesel engine vehicles and low emission vehicles and fuels, especially low sulfur fuels.

Urban planning: improvement of the energy efficiency of buildings and concentration of cities to achieve greater efficiency.

Electricity generation: increased use of low-emission fuels and non-combustion renewable energy sources (solar, wind or hydroelectric); joint generation of heat and electricity; and distributed energy generation (for example, electricity generation through small grids and solar panels).

Municipal and agricultural waste management: waste reduction, separation, recycling and reuse or reprocessing strategies; improved methods of biological waste management, such as anaerobic digestion to produce biogas, which are viable, low-cost alternatives to solid waste incineration (where incineration cannot be avoided, the use of combustion technologies with rigorous emission controls).

In addition to outdoor air pollution, indoor smoke poses a serious health risk to the approximately 2.6 billion people who cook and heat their homes with biomass and coal fuels. About 3.8 million premature deaths in 2016 were attributable to household air pollution. Almost all occurred in low- and middle-income countries. Household air pollution is also a major source of outdoor air pollution, both in urban and rural areas, and can account for 50% of pollution in some regions of the world.