China Air Quality Study Has Good News and Bad News

China Air Quality Study Has Good News and Bad News

BEIJING — You’re moving to China with your family, and you’re excited but also concerned: What might the country’s notorious smog do to your and your children’s lungs?

Here’s how you can feel the fear and move to China anyway, while minimizing your health risks:

Relocate to Guangzhou, the capital of the southern province of Guangdong, near Hong Kong. Second best: move to Shanghai.

Don’t move to Beijing, Chengdu or Shenyang, if you can help it.

Those are some conclusions to be drawn from a new study of air quality in five major cities by a team of researchers at Peking University led by Chen Songxi, a statistician at the university’s Guanghua School of Management.

In an interview, Mr. Chen said the study was prompted by a sense of “disgust” at air pollution. “I felt that as scientists we should do something about the situation facing a billion Chinese people,” he said.

There was both good and bad news in the report, titled “Air Quality Assessment Report (2): A Statistical Analysis of Air Pollution in Five Chinese Cities” and published online.

The team scrutinized three years of air quality data for the measure known as PM 2.5, the fine particulate matter that is especially hazardous to health. One source of the data was the Chinese Ministry of Environmental Protection. The other was the United States Embassy in Beijing and consulates in Guangzhou, Shanghai, Chengdu and Shenyang.

By using two independent data sets, the researchers answered a second question: Is the Chinese government’s air quality data trustworthy? The answer: Yes, at least in these five cities. That was one piece of good news.

China began releasing PM 2.5 figures for hundreds of locations in 2013, five years after the United States Embassy began publishing readings from monitors on its grounds that drew wide attention among Chinese. Suspicions linger to this day about the reliability of the Chinese government data.

Another piece of good news: PM 2.5 levels declined over the last three years in all five cities. In Beijing, they fell from 99 micrograms per cubic meter to 81, and in Shanghai from 61 to 50. In Guangzhou, they fell from 54 to 39.

That was because of two factors: stricter emissions regulations that took effect on Jan. 1, 2015, and a slowing economy.

“The economic downturn helped,” Mr. Chen said.

But there was bad news, too. In all five cities, the air pollution readings remained higher than the World Health Organization’s upper safety limit of 35 micrograms of PM 2.5 per cubic meter.

China uses a considerably more liberal standard, classifying up to 75 micrograms as “good.” Many readings regularly exceeded that.

The researchers defined a level of under 35 as “good,” and under 75 as “light” pollution, and found that Guangzhou and Shanghai had the most “good” or “light” days. About 80 percent of days each year fell into those categories. Chengdu and Shenyang had about 60 percent. Beijing came last with 50 percent.

In addition, Beijing and Chengdu suffered the most prolonged spells of heavy pollution, which the team defined as readings of 150 or higher. Even Shanghai and Guangzhou did not have more than 37 percent “good” air days.

“This shows the grave challenge facing China in its air pollution prevention efforts,” the report says.

Mr. Chen’s interest was ignited after a colleague in the United States sent him the United States Embassy air quality readings in 2013.

“The more I looked at it, the more disgusted I felt,” Mr. Chen said. “Then, on a very polluted day in early March” of 2014, “I said, ‘I have to do something.’ I called together a team.”

To test the accuracy of the Chinese government data, the researchers used readings from two or three ministry monitors in each city as close as possible to the American sites. They found a “high” similarity, the report says.
Photo



Beijing last December during a period of heavy smog. It remains China’s worst city for air pollution, researchers found. CreditReuters



“They show a lot of consistency,” Mr. Chen said. “They won’t be exactly the same, because of data randomness and because they’re not at exactly the same locations.”

“If they were still manipulating the data, that would be really hopeless and I’d leave China,’’ he said. “But it does show that the government and the Ministry of Environmental Protection are serious.”

Still, there were significant data problems on the Chinese side, he said.

The Ministry of Environmental Protection website gives hourly readings, “but it doesn’t provide historical data,’’ Mr. Chen said. “You have to grab it, hour by hour. The government wants to do something about this, but not 100 percent.”

The report recommends improving data collection and publication.

The team also factored in meteorological factors and consumption of coal, petroleum and diesel to get a better picture of the relations among emissions, weather and pollution. But here too they encountered a lack of information.

“The economic and energy data are very sparse,’’ Mr. Chen said. “We couldn’t find data on consumption, especially of petroleum products. We don’t know how much gasoline was sold in 2014, and we think petroleum products may be a bigger problem than coal in Beijing.”

Asked where a family moving to China should settle to minimize exposure to polluted air, Mr. Chen said, “I grew up in Beijing and I love Beijing, so you put me in a very hard position.”

The North China Plain, where Beijing is, and the Sichuan Basin, where Chengdu is, “are not good places to be. They’re not suitable for heavy industry,’’ Mr. Chen said. Their physical settings trap pollutants. “If you have heavy industry there, this is what you’ll get.”

“Shanghai and Guangzhou are more fortunate,’’ he said, “because they’re close to the sea and have more rainfall.”

Beijing’s saving grace: a strong northwesterly wind in winter that helps clear the air. But that doesn’t address the source of the problem. Another recommendation: reduce emissions.