New WHO Data: 99% of the Global Population Breathes Poor-Quality Air

New data from the World Health Organization (WHO) reveal that 99% of the global population breathes air that exceeds WHO air quality limits.

The 2022 update of the WHO’s air quality database introduces, for the first time, ground measurements of annual mean concentrations of nitrogen dioxide (NO2), a common urban pollutant and precursor of particulate matter and ozone. It also includes measurements of particulate matter with diameters equal or smaller than 10 μm (PM10) or 2.5 μm (PM2.5).  Both groups of pollutants originate mainly from human activities related to fossil fuel combustion.

Research on the effects of air pollution on humans has been growing and points to significant harm caused by even low levels of many air pollutants. Particulate matter, especially PM2.5, is capable of penetrating deep into the lungs and entering the bloodstream, causing cardiovascular, cerebrovascular (stroke), and respiratory impacts. There is emerging evidence that particulate matter impacts other organs and causes other diseases as well.

NO2 is associated with respiratory diseases, particularly asthma, leading to respiratory symptoms (such as coughing, wheezing or difficulty breathing), hospital admissions, and visits to emergency rooms.

More than 6,000 cities in 117 countries are now monitoring air quality, which is an almost six-fold rise in reporting since the database was launched in 2011. In the 117 countries monitoring air quality, the air in 17% of cities in high-income countries fall below the WHO’s Air Quality Guidelines for PM2.5 or PM10.  In low- and middle-income countries, air quality in less than 1% of the cities complies with WHO recommended thresholds.

In the 4,000 cities/human settlements in 74 countries that collect NO2 data at ground level, their aggregated measurements show that only 23% of people in these places breathe annual average concentrations of NO2 that meet levels in the recently updated version of WHO’s Air Quality Guidelines.