Metro

Time to correct flawed air pollution index

By Xiao Huo (China Daily)
Updated: 2009-12-09 07:59

Environmental protection officials in Beijing have had an easy time since the Olympics last summer.

The city recorded fewer polluted days following its smog-cleaning campaign for the Olympics, and authorities last month announced that the city's air quality has reached the highest level in decades after meeting its annual target for "blue sky" days one month ahead of schedule, for two consecutive years.

But the fact that Beijing's air is now clean is bad news for reporters.

Feeling a need to challenge authorities with more probing questions on air pollution, I suggest the Beijing municipal environmental protection bureau correct flawed monitoring standards that have been used for more than a decade.

Both Chinese and foreign experts have said that the current air pollution index in Beijing, and across the country, is far from perfect. They point out that the current index excludes ozone, a key pollutant from car emissions. Chinese authorities instead monitor pollutant particles with sizes smaller than 10 micrometers, while European and North American countries focus on a more specific range of particles under 2.5 micrometers, and include ozone particles.

In short, the Chinese system creates an unfairly low index compared with other countries.

According to the US Environmental Protection Agency, particles less than 10 micrometers in diameter (also known as PM10) pose a health concern because they can accumulate in the respiratory system.

But particles less than 2.5 micrometers in diameter (known as PM2.5), referred to as "fine" particles, are believed to pose the greatest health risks. Because of their small size (about 1/30th the average width of a human hair), these fine particles can lodge deep into the lungs.

The distinction also partly explains that while yesterday's air quality was recorded as "very unhealthy" at the local environmental bureau's 28 monitor stations citywide, the independent monitor set by the US Embassy in Beijing's car-populated business area said it was "hazardous".

I suggest Beijing authorities get active and take the opportunity to tackle air pollution now, just as they did before the Olympics.

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(China Daily 12/09/2009 page27)