Clearing the Air

Clearing the Air

New air-quality monitoring criteria set to be introduced

On November 8, seven Beijing residents, including a representative from a local environmental organization, were invited by the Beijing Municipal Environmental Protection Bureau (BMEPB) to visit its air-quality monitoring center.

The visit was the first of a regular program of visits that will take 40 visitors to the center every Tuesday in hopes of giving them a better understanding of how airquality data are collected and analyzed.

The program marks the first time Beijing’s environmental watchdog has opened its doors to individual visitors since it was established in 1974, although 340 schools, companies and other organizations have taken educational tours of the facility since it opened for group visits in 1997.

“We want the public to see how we work and further convince the public of the sincerity of our efforts,” said Wang Xiaoming, a spokesman for the BMEPB.

The move came amid growing doubts from the public over the air-quality monitoring standards adopted by Beijing authorities. Such doubts were triggered by different air condition reports released by the BMEPB and the U.S. embassy in Beijing at the end of October.

Since October, haze and fog have blanketed Beijing on three occasions. The thick haze, which covered Beijing for as much as a week at a time and reduced visibility to a few meters, raised public concerns over the city’s air quality and its impact on people’s health.

On October 30, air monitoring data from the U.S. embassy in Beijing suggested that the density of PM2.5, fine particles with a diameter shorter than 2.5 microns, in the air was about 250 to 350 and the general air pollution index (API), an indicator of the air quality, was 425, reaching the level of “hazardous,” the worst ranking on the pollution scale according to U.S. standards. However, the API released by the BMEPB on the same day was only 132 and the air was categorized as “slightly polluted.”

An API reading below 50 indicates “excellent” air quality, while 50 to 100 shows“healthy” air and above 100 means the air is polluted, according to China’s standards.

Different measurements

The U.S. embassy’s evaluation of Beijing’s air quality often differs markedly from the offcial Chinese rating. The embassy rated the city’s air quality as “hazardous”on several occasions in October. On October 9, the reading was listed as “beyond index,”allegedly meaning the amount of pollutants exceeded measurable levels.

Established in 2008, the embassy’s airquality monitoring system produces hourly updates of air quality. The readings are for ozone and for the concentration of PM2.5, the tiny airborne pollutants that cause haze and which can travel deep into the lungs and damage people’s respiratory systems.

The PM2.5 standard was created by the U.S. Environmental Protection Agency (EPA) in 1997 for measuring air quality by counting fne particles of 2.5 microns in diameter and smaller.

Such particles are found in smoke and haze, or they can form when gases emitted from power plants, industries and automobiles react in the air, according to the EPA.

Part of the difference between the U.S. embassy and BMEPB figures can be explained by the use of different standards. China currently measures PM10 levels while the U.S. embassy measures the concentrations of PM2.5.

“The particulate matter currently measured in China is between 2.5 and 10 microns in diameter and is known as PM10,”said Du Shaozhong, Deputy Director of the BMEPB.

By defnition fog is the accumulation of vapor in the air and is largely transparent. Du said that the hazes that blanketed Beijing should actually be referred to as “smog,”which is the combination of pollutants and fog.

Tang Xiaoyan, a professor at the College of Environmental Sciences and Engineering of Peking University, said research showed that Beijing’s haze is caused mostly by PM2.5. “The contribution of larger matter is rather limited,” she said.

But Du pointed out that while the U.S. embassy releases hourly updates of its PM2.5 monitoring results, the accuracy of these results is questionable because the data are only collected from a single spot.

When the BMEPB evaluates Beijing’s air conditions, Du said it gathers descriptive statistics from 27 major monitoring stations scattered throughout the city and this amounts to a more scientifcally representative sample.

“In addition to the major stations, which monitor pollutants such as nitric oxide, sulfur dioxide, carbon monoxide and PM10, the bureau also has several experimental substations located along major traffic arteries citywide that gather other data, such as the impact of car exhaust fumes and PM2.5,”said Li Yunting, an engineer with the National Environmental Monitoring Center.

A press offcer with the U.S. embassy in Beijing also acknowledged that the air-quality monitoring system used by the embassy differs from that used by the BMEPB in terms of its purpose and area coverage, so fgures from the two sources have no common basis of comparison.

New criteria

Facing accusations of underestimating air pollution in the capital, authorities in Beijing have begun to consider improving the way they measure air quality.

“The BMEPB applies the current national standard, which is being amended. Technically we are ready to adopt the PM2.5 standard,” Du said.

China adopted the PM10 standard in 1995 that targets inhalable coarse particles between 2.5 and 10 microns in diameter. It was in 1996 that the BMEPB changed their measuring standards from PM100 to PM10.

“Currently, coarse particles are the focus of air-quality monitoring in China. Just like removing stones before clearing dust on a road, we need to first deal with larger particles before handling the smaller ones,” Du said.

While the concentration of coarse particles in Beijing’s air has decreased, the city’s concentration of fne particles regularly exceeds safe levels.

“Fine particles are far more dangerous to human health and may cause cardiac and respiratory diseases as these small particles can be inhaled into the respiratory system, while coarser particles are blocked by the nostrils,” said Pan Xiaochuan, a professor at the School of Public Health of Peking University.

Pan said that adopting the PM2.5 measurement to check air quality is a worldwide trend. “It is only a matter of time before Beijing follows suit,” he said.

According to Wei Qiang, another engineer with the National Environmental Monitoring Center, the center has established monitoring stations that analyze Beijing’s pollutant intensity for PM2.5 and even PM1.“The data will be released in the future, when the city adopts the PM2.5 standard,”Wei said.

Early in 2007, the National Environmental Monitoring Center announced that it had accumulated some experience of PM2.5 monitoring by carrying out haze monitoring pilot programs in Tianjin, Shanghai and Chongqing municipalities, Guangzhou and Shenzhen in Guangdong Province and Nanjing in Jiangsu Province.

On November 1, the Ministry of Environmental Protection (MEP) implemented a regulatory document in which it set the standard for measuring PM2.5 for the frst time.

However, experts also warned that many Chinese cities would have major diffculties in meeting the PM2.5 standard if it were adopted.

Pan said it would be difficult to ensure the standards are reliable and effective and to decide whether the PM2.5 standards should be based on number concentration or mass concentration.

“The MEP has considered adding PM2.5 into the national air quality standards for many years, but hasn’t done so. Decisions such as these may be the reason,” he said.

However Pan also expected that revised standards containing PM2.5 would be introduced within the next five years. In September Zhou Jian, Vice Minister of Environmental Protection, told a conference that China will re-evaluate and revise a series of environmental quality standards over the next fve years.

Clean-up campaign

Du admitted that there was room for improvement in the BMEPB’s air-quality data release.

“We haven’t done enough, or done it fast enough, in terms of educating people about air-quality monitoring,” Du said in a microblog posting on November 1. “Many people have no idea what we are doing because we haven’t provided an information service that is user-friendly enough. We have put out a lot of science jargon but never explained what it meant.”

Beijing has undertaken a massive project to clean up its air since 2008.

Measures taken include moving polluting enterprises out of the city, getting residents in the old city quarter to switch from coalfred to electric heating and expanding public transportation.

As a result, Beijing’s air quality has gradually been improving, the BMEPB said in a statement on November 6.

According to the statement, Beijing had 63 days of excellent air quality in the frst 10 months of this year, 12 days more than during the same period in 2008.

Additionally, the API on 239 days, so far, this year has been below 100, indicating good air quality.

The statement said the dense fog that blanketed the city was to blame for the nine days the city failed to reach the national blue sky standard in October. A similar situation occurred over the same period of 2008 and 2010, it added.

In April, the Beijing Municipal Government launched a fve-year action plan to improve the environment by phasing out coal-fred boilers, saying excellent or good air conditions are expected for 80 percent of the days in the year by 2015.