29 February 2020
New Delhi was the most polluted capital city last year, just like it was in 2018. That finding comes IQ AirVisual, a Swiss-based group that studies air-quality measurements from around the world.
India was home to 21 of the world's 30 most polluted cities, the group reported.
IQ AirVisual said the study measured levels of a kind of particulate matter (PM), called PM2.5, in major population centers.
Researchers chose to examine PM2.5 because it "is the pollutant widely regarded as most harmful to human health," the report said.
These small particles, less than 2.5 microns in length, can go deep into the lungs. High PM2.5 levels can cause health problems, including cancer and heart disease, the report notes.
Researchers examined data about PM2.5 concentrations in the air. The information was collected hourly, from ground-based monitoring systems.
In 2019, New Delhi's average yearly concentration of PM2.5 in a cubic meter of air was 98.6, the report said. That is more than twice the level of Beijing, which had an average of 42.1 during the year. Beijing was the ninth most polluted capital city, the study found.
New Delhi's harmful air has a number of causes. They include pollution from motor vehicles and industrial centers, dust from building projects and smoke from the burning of waste.
Late last year, rising air pollution levels forced Indian officials, who called the crisis a public health emergency, to close schools twice.
The study, however, said India did see "widespread improvements" in PM2.5 levels compared to 2018. These improvements were likely a result of better weather conditions, government cleanup efforts, and an overall economic slowdown.
"Despite improvements, India still faces serious air pollution challenges," the report said.
I'm John Russell.
Neha Dasgupta reported on this story for Reuters. John Russell adapted it for Learning English. George Grow was the editor.
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Words in This Story
particulate – n. of or relating to minute separate particles
concentration – n. the amount of an ingredient in a mixture
monitor – v. to watch, observe, listen to, or check (something) for a special purpose over a period of time
challenge – n. a difficult task or problem : something that is hard to do
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