tiistai 26. helmikuuta 2013

How much is hazardous? - Air pollution in Beijing

Everyone who has visited in China's capital city of Beijing during the cold winter months, knows how polluted the air can be. I was lecturing during two winter periods some five years ago in the Peking University and during both of the visits I was able to observe the situation myself. The research group in Peking University was already then measuring the urban air quality within the campus area and I was able to see the real measurement data. It was something, I have seen only in some of the other rapidly growing and highly polluted megacities.

Since my visits, the public discussion around the topic of air quality in Beijing has been increasing. It was the decision of the U.S. Embassy in Beijing to start monitoring the levels of fine particles, called PM2.5 (which stands for particulate mass below 2.5 µm in diameter, particles which can enter deep into the respiratory system) and to report the data in social media (twitter @BeijingAir) that rose the air quality issue to almost political level. One could well understand that this type of activity within another country is almost as looking for an conflict and certainly raises emotions.

In spite of the people’s observations, the Chinese environmental authorities have long ignored the seriousness of the air quality problem and systematically claimed that the situation is actually getting improved. While there have actually been activities to reduce the emissions, especially within the Beijing urban area, the overall air quality situation does not show improvements.

The recently reported values of the PM2.5 concentrations and observed health problems have naturally been an increasing concern also within the local citizens. As more and more pressure was building up, the Chinese environmental authorities started to report more openly of their own measurements. This winter has shown the real change and reports from many industrialized areas of China are published on web site of the Chinese environmental agency. Hourly air quality updates are now available online for more than 70 cities.

Record high concentrations in Beijing air

Air pollution in Beijing has during this winter reached several times record levels. Early January was probably the worst. According to the U.S. Embassy twitter @BeijingAir, on Saturday January 12th PM 2.5 readings surged to 886 µg/m3, exceeding the U.S. Environmental Protection Agency’s highest grading of "hazardous" which is anything between 301-500, and far beyond the level deemed acceptable by the World Health Organization, which is a 25 µg/m3 mean over a 24 hour period.

The Chinese authorities reported similar values. According to an official monitoring center in Beijing, levels of PM2.5 were well above 600 micrograms per cubic meter in several places on Saturday 12th of January, and may even have hit 900. These values are strikingly similar to those estimated to happen during the London smog episode in 1952.

One expert quoted by Chinese media attributed this spike in pollution to a series of windless days that allowed pollutants to accumulate. The cold winter weather also relates to low mixing within the atmosphere and therefore pollutants do not dilute in larger air masses. The wind can be a problem when it does blow, too. In the outlying provinces that are part of Beijing’s airshed, there is a great deal of heavy industry. Pollution regulations are much harder to enforce there. And, in this colder-than-average winter, people have been burning more coal and wood than usual.

Closer look of the measurements at the Peking university campus indicate that the problem is actually more regional than just of local origin. This is evident also in view of the efforts made within Beijing urban center. It is not enough to clean and control the local pollution from vehicles and energy use, as large fraction – often majority – of pollution is regional and originates from a large industrialized area surrounding the city itself.

How serious this is for the health?

Recently a web publication Behind the wall, which is a blog site of NBCNews commented the health consequences of the pollution. Steve Andrews, an environmental consultant who has analyzed the @BeijingAir data, said. “While when we look at the U.S. Embassy data … over 80 percent days exceeded what would be considered healthy air quality and more days were hazardous than good.”

Andrews said that Beijing's pollution levels were "six or seven times higher than the U.S.'s most polluted city." "Air pollution at these levels likely shortens life expectancy by about five years," he added. Exposure to PM2.5 pollution can lead to cardiovascular and lung disease, and in a long term increases the risk of cancer.

The values reported in Beijing are way beyond those we are familiar with in Europe or in US. In Helsinki for instance, the PM2.5 levels are on average around 10 µg/m3 and the expected shortening of life expectancy at these levels is of the order of 3-6 months.

According to a study by Greenpeace and Peking University’s School of Public Health, PM2.5 air pollution may have led to 8,572 premature deaths last year in four major Chinese cities including Beijing.

New openness

It has taken about half a century for major European and U.S. cities to clean up their urban air to the levels that we meet today. It is expected that a long way needs to be travelled before the situation in China shows similar improvements. However, the first steps of openness in publishing the data and discussing the real problems have been taken. This is a positive signal!

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