According to an unprecedented compilation of air quality data released on September 29, 2011 by the World Health Organization (WHO), air pollution is reaching levels that threaten people’s health in many cities. This information includes data from nearly 1100 cities across 91 countries. The WHO estimates that more than 2 000 000 people die every year from breathing in tiny particles present in indoor and outdoor air pollution. PM10 particles, which are particles of 10 micrometers or less that 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 for PM10 is 20 μg/m3 as an annual average but the data released shows that average PM10 in some cities has reached up to 300 μg/m3. WHO is calling for greater awareness of health risks caused by urban air pollution, implementation of effective policies, and close monitoring of the situation 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, which would be considered a major public health gain.
