The World Health Organization released an unprecedented compilation of air quality data last week hat shows a dangerous increase in air pollution levels. According to the data, over 2 million people die every year from indoor and outdoor air pollution, and the collected air quality levels are alarmingly threatening people’s health in many cities.

According to WHO, the responsible element in air pollution are PM10 particles, pieces that are 10 micrometers or less, which can “penetrate into the lungs and may enter the bloodstream, can cause heart disease, lung cancer, asthma, and acute lower respiratory infections.”

The WHO air quality guidelines dictate that a maximum annual average of PM10 particles should be at 20 micrograms per cubic meter. Yet, the data indicate some cities as having already reached and surpassed that maximum annual average with an air quality measure of 300 micrograms per cubic meter—15 times the recommended WHO levels. According to the WHO, only a few cities currently meet its guidelines in air quality.

WHO also states that elevated levels of fine particle pollution are common across many urban areas, and these particles originate from combustion sources, like power plants and motor vehicles. “In both developed and developing countries, the largest contributors to urban outdoor air pollution include motor transport, small-scale manufacturers and other industries, burning of biomass and coal for cooking and heating, as well as coal-fired power plants,” the organization explains. “Residential wood and coal burning for space heating is an important contributor to air pollution, especially in rural areas during colder months.”

In 2008, there were an estimated 1.34 million premature deaths due to air pollution in cities. Of these deaths, 1.09 million lives could have been saved had the WHO guidelines been met. According to the WHO, the number of deaths attributed to air pollution in cities has increased from the 2004 estimate of 1.15 million people. The organization ascribes this increase to higher concentration of air pollution and a rise in urban population. The organization also credits improved data availability and enhanced methodology with the difference in calculations.

In the wake of these grueling statistics, the WHO is calling for greater awareness of health risks caused by urban air pollution and the implementation of effective policies, in addition to close monitoring of air quality levels in cities. “A reduction from an average of 70 µg/m³ of PM10 to an annual average of 20 µg/m³ of PM10 is expected to yield a 15% reduction in mortality—considered a major public health gain,” the WHO explains. “At higher levels of pollution, similar reductions would have less impact on reducing mortality, but will nevertheless still bring important health benefits.”

“Solutions to outdoor air pollution problems in a city will differ depending on the relative contribution of pollution sources, its stage of development, as well as its local geography,” said Dr. Carlos Dora, WHO coordinator for Interventions for Health Environments in the Department of Public Health and Environment. “The most powerful way that the information from the WHO database can be used is for a city to monitor its own trends in air pollution over time, so as to identify, improve and scale-up effective interventions.” (Read more about Dora’s research on the link between transport and health in a previous post on TheCityFix here.)

For more information about air quality data from the World Health Organization, read the press release and browse the database.