"About 86 percent of people living in urban areas worldwide — 2.5 billion people — are being exposed to air pollution levels roughly seven times greater than World Health Organization guidelines, according to new research, led by George Washington University researchers and published in the Lancet Planetary Health journal.
Based on about two decades of data from more than 13,000 cities, the researchers attributed 1.8 million deaths in 2019 to these unhealthy levels of urban air pollution, primarily in the form of tiny particulate matter (PM2.5) — microscopic liquid droplets or solid particles in the air that are inhalable. The researchers estimate that about a third of the deaths attributed to particulate matter could have been avoided if cities had met the WHO guidelines. Generally, the smaller the particles, the greater their chances of damaging people’s health. For instance, PM2.5 particles, which have a diameter of 2.5 micrometers or less, are small enough to invade the lungs and bloodstream."
Linda Searing reports for the Washington Post February 6, 2022.
Advertisement 
