报告称南亚和中亚人民呼吸着污染最严重的空气

A new study has found that people living in South and Central Asia experience some of the highest levels of air pollution in the world.

The air in these areas has the highest amounts of the most kind of air pollution. PM2.5 is atmospheric particulate matter that is 2.5 microns in diameter or less. A micron is one millionth of a meter. PM2.5 is so small that it can enter human lungs and the blood.

The Switzerland-based company IQAir released its latest study on Tuesday. The company operates an air quality information system. The yearly IQAir reports began in 2017.

Glory Dolphin Hammes is chief of IQAir North America. She told VOA: "PM2.5 actually kills more people than any other air quality pollutant."

Based on data from IQAir's worldwide network, Bangladesh is the country with the highest levels of PM2.5 air pollution. Chad, Pakistan, Tajikistan and India are also among the five nations with the lowest air quality.

IQAir found that New Delhi, India, is the capital city with the most PM2.5 pollution. Dhaka, Bangladesh; N'Djamena, Chad; Dushanbe, Tajikistan; and Muscat, Oman, are the other capital cities rated as having extremely polluted air.

People seeking the world's cleanest air will find it in the French overseas territory of New Caledonia. The territory's main city, Noumea, is at the top of IQAir's clean air ranking.

Other places where the air is very clean include the U.S. Virgin Islands and Puerto Rico in the Caribbean. Cape Verde, in the Atlantic Ocean off the coast of Africa, also has very little air pollution.

Some parts of the developing world lack enough monitoring, Dolphin Hammes said. Those areas include parts of Africa, the Middle East and South America. Developed countries usually have a greater number of air quality monitors than developing countries and areas.

Monitoring is at a higher level than in past years in some countries, she said. With that additional monitoring, Dolphin Hammes noted, "there are two countries (Chad and Tajikistan) that are among the most polluted countries that weren't on our report last year."

In 2021, air pollution levels increased from those of a year earlier: the first year of the COVID-19 pandemic. In 2020, the world saw a decrease in air pollution because of less ground and air transportation. Another reason for the rise in air pollution last year was an increase in wildfires, Dolphin Hammes said.

Last year, the World Health Organization cut the recommended yearly PM2.5 limit by half – from 10 micrograms per cubic meter to five micrograms per cubic meter. The WHO said the reduction would prevent millions of deaths worldwide.

Scientists supported the new recommendations. But they worry that some countries would have trouble reaching them. Much of the world was already failing to meet the 10-microgram limit, Reuters news agency reported.

IQAir's yearly reports are based on PM2.5 measurements from what is now a total of 6,475 cities in 117 countries, regions and territories. The worldwide information comes from "tens of thousands of regulatory and low-cost air quality monitoring stations," the company said. The stations are operated by governments, noNPRofit organizations, research centers and citizen scientists.

I'm Steve Herman.

Steve Herman reported this story for VOA Learning English.

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diameter –n. the distance through the center of something from one side to the other

monitor –v. to watch, observe, listen to, or check (something) for a special purpose over a period of time

region –n. a part of a country or of the world, that is different or separate from other parts in some way

regulatory –adj. making or concerned with making official rules about what is acceptable in a particular business, activity or field

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