Less Data from Africa
The UN says PM2.5 density should not top 25 microgram per cubic meter (25 mcg/m3) of air in any 24-hour period. China has set the bar at 35 mcg/m3.
More than a million premature deaths in China each year are caused by air pollution, according to the WHO. Recent calculations put the toll at up to twice that figure.
Across a large swathe of northern India and north-central China, meeting WHO standards year-round for PM2.5 pollution would increase life expectancy up to six or seven years, according to the Air Quality Life Index, developed by researchers at the Energy Policy Institute of Chicago.
In India, small particle pollution exceeds WHO limits by 500 percent, even if air pollution in general declined significantly last year, with 98 percent of cities monitored showing improvements.
Among the club of 36 rich OECD nations, South Korea was the most polluted for PM2.5, counting 105 of the worst 1,000 cities on the index. In Europe, Poland and Italy count 39 and 31 cities, respectively, in this tranche.
Other parts of the world such as Africa and the Middle East lacked data.
“What cannot be measured cannot be managed,” Hammes said. “Africa, a continent of 1.3 billion people, currently has less than 100 monitoring stations that make PM2.5 data available to the public in realtime.”