The United States space agency published a map in September that showed how rates of premature deaths from air pollution vary around the world. It indicated that northern China has one of the worst rates, attributed to the density of a deadly fine particulate matter, known as PM 2.5, that often results from coal burning. The map was based on data collected by a research team led by Jason West, an earth scientist at the University of North Carolina.

The map also showed that the rate in northern China — what appears to be about 1,000 or more deaths each year per 1,000 square kilometers, or 386 square miles — is matched by that of northern India, in a diagonal belt stretching from New Delhi southeast to Calcutta. Those acutely polluted areas are colored dark brown on the NASA map. (Europe was perhaps surprisingly colored a deep brown too, though the rate was not as bad as that of the two Asian nations.)

Various recent studies and data suggest that air quality in Delhi is worse than in Beijing, though India’s air pollution problems do not get nearly as much attention on the world stage as those of Beijing. One study shows that Indians have the world’s weakest lungs. The World Health Organization says India has the world’s highest rate of death caused by chronic respiratory diseases, and it has more deaths from asthma than any other nation.

Yet, Indians and foreigners living in Delhi do not express anxiety about the air the way that residents of Beijing and other Chinese cities do. Air purifiers are a rarity in homes there, and face masks are generally not seen on the streets. The Indian news media do not cover air pollution to nearly the same extent the Chinese media do. (Government censors in China had blocked widespread coverage of the problem for years, but they loosened the restrictions during an infamous surge in pollution across northern China in January 2013; now even official state-run Chinese news organizations report regularly on air pollution.)

Ananth Krishnan, the China correspondent for The Hindu, has been mulling over this disparity in public dialogue on air quality. He posted tweets about it in December, during a bad pollution day in Delhi. One of his conclusions was that the United States Embassy in Beijing had helped raise awareness in China by posting on Twitter for the past several years the air quality readings from a rooftop monitoring device.

The embassy “did play a role in PM 2.5 awareness; maybe right time to start @USAndIndia air monitor,” Mr. Krishnan wrote on Twitter.

In part because of the public release of PM 2.5 readings by the United States Embassy, prominent Chinese commentators like the real estate tycoon Pan Shiyi began asking on microblogs why the Chinese government was not making available data that it had collected. This helped put the issue in the spotlight, and Chinese officials then agreed to release the data for many cities across the country.

Mr. Krishnan said in an interview that Delhi had been making the same kind of data available to the public well before Chinese officials agreed to release their numbers, and that the Indian numbers proved without a doubt that the air quality in the Indian capital was poor. However, he said, there has never in India been populist demand for the government to change policy to improve the air, as there is now in China.

“I think when you have the sense that they’re hiding something, it galvanizes public attention in a counterintuitive way,” said Mr. Krishnan, who has lived in Beijing since early 2010.

“I don’t think the Indian media has given enough attention to this issue,” he added. “I remember an Indian environmental scholar visited Beijing a few months ago, and he was surprised that pollution was getting so much attention in the press here.”

Coverage of air quality by the Indian news media “will have to change very soon,” Mr. Krishnan said.

On Saturday, China Daily, an official English-language newspaper, reported that December was the worst month of 2013 for air quality in China. More than 80 percent of the 74 cities with official air monitoring devices failed to meet the national air quality standard for at least half of December, the report said, citing information from the Environmental Protection Ministry. That was twice as many cities as the number in November.

In some of the smog attacks in December, visibility in cities was reduced to less than 10 meters, or 33 feet. Levels of five major pollutants increased that month. The monthly average of PM 2.5, the same particulate matter that scientists deem to be most harmful to human health, rose by almost 56 percent.

The report also said Beijing officials would issue “guidance” to tell the public whether the weather would be conducive to the setting-off of fireworks and firecrackers during the Lunar New Year holiday, which begins this week. Officials have said that smoke from the explosives contributes to air pollution. The four levels of guidance are: proper, not quite proper, not proper and extremely improper.

via India and China, Besieged by Air Pollution – NYTimes.com.