Doctors blame air pollution for China's asthma increases,(all over the urban world)

[Guest guest]

The Lancet, Volume 368, Issue 9537, Pages 719 - 720, 26 August 2006

doi:10.1016/S0140-6736(06)69267-2 Cite or Link Using DOI

Doctors blame air pollution for China's asthma increases

Original Text Watts

Specialists estimate that the number of asthma cases in China has risen by 40% in the past 5 years. Prevalence in some cities is near 4%. With 16 of the world's worst air-quality hotspots within its borders, China is starting to think its pollution problem may be to blame. Watts reports.

Of all the mega-statistics that can be used to illustrate China's spectacular economic development, the dramatic rise in the prevalence of asthma is, not surprisingly, low down on the list of boasts that the government in Beijing would like to make to the world.

But—just like the connected increase of cars on the roads, pollution in the air, and farmland-turned-into-factories—the aggravation of the nation's respiratory tracts is a sure sign that the planet's most populous nation is wheezing its way towards modernity with at least as many pants and gasps as Britain, the USA, or Japan during their most rapid phases of growth.

According to the China Journal of Pediatrics, the prevalence of asthma among urban children rose 64% between 1990 and 2000, when it hit 1·97%. In bigger cities, where the air quality is lower and awareness of the ailment is higher, this figure more than doubled. Worst affected was Chongqing—one of the fastest growing metropolises in China—where the prevalence among children younger than 14 years was 4·63%.

Strengthening the association of asthma with urbanisation, the least-affected cities were those that have lagged behind in developing their economies, notably Lhasa (the capital of Tibet) with 0·57%, and Xining (the capital of Qinghai province) with 0·25%. Though even these cities notched up rapid increases in the disorder during the 1990s.

More recent data is not available, nor is there a nationwide figure for adults. But Chinese specialists estimated that the number of asthma cases they see has risen by about 40% in the past 5 years. Reported cases in the adult population suggests the prevalence is roughly half that among children.

As with all statistics in this vast, diverse, and economically unbalanced nation, China's asthma figures need to be taken with a health warning. Boys, for example, were shown to have a 75% higher chance of seeing a doctor for asthma than girls. Rather than show greater vulnerability among male children, this disparity is just as likely to reflect a cultural preference for male offspring.

But the very facts that asthma data are now being collected and specialists trained in the field show that the government is starting to be more aware of environment-related health problems. Just as significantly, it reveals that more and more people now have the economic means and the medical knowledge to consult a doctor over coughs that might once have been ignored as too trivial to warrant attention. Thanks to these trends, the Chinese Medical Association last year established the Chinese Asthma Alliance, which organises training programmes in the provinces. Drug makers, such as GlaxoKline, are experiencing a rapid growth in sales of inhalers. And, little by little, more research is being carried out on the genetic and environmental origins of the disorder.

The most obvious cause is air pollution—arguably the most dangerous side-effect of China's economic growth. According to the World Bank, China is home to 16 of the planet's 20 worst cities for air quality. It is evident from the haze that envelops Hong Kong harbour in the south, to the thick smog that obscures the streets of Linfen in Shaanxi in the north, and it is not just an eyesore. The health costs are increasingly apparent. Respiratory diseases are the leading cause of death in China. Along with one of the highest smoking rates in the world, doctors blame smog for sharp rises in cases of bronchitis, pulmonary fibrosis, tuberculosis, and lung cancer.

Beijing is among the worst affected. Last year, satellite sampling by the European Space Agency revealed that sulphur dioxide levels in the capital and northeast China were the highest in the world. On a day of average haze, some of the more distant tower blocks fade from view. During the worst periods, every building in this city of 14 million people seems to melt into the grey air. Such days are supposed to be getting fewer. Over the past 5 years, the Beijing municipal government has spent 67 billion yuan (US$8·4 billion) relocating some of the dirtiest factories, tightening rules on sulphur emissions, and introducing a fleet of electric and gas-fuelled buses.

But even though more and more homes are switching from coal to gas, the environmental benefits are being outweighed by the dramatic increase in traffic. The number of cars on Beijing's roads has more than doubled in the past 5 years to 2·4 million. Most burn cheap high-sulphur fuel, which creates dirtier—and more unhealthy—emissions. The environmental protection agency estimates that road vehicles are responsible for 70% of the sulphur in the air.

Every day, Beijing television announces the air-quality forecast along with the weather. On a level one “excellent” day—usually following a strong and prolonged breeze—there might enough clarity to see the Fragrant Hill to the west of the city. On a level five “severe” day—usually at the end of a windless week—the pollution build-up is so bad that teachers are advised to keep children indoors at playtime, and asthma sufferers are warned not to venture outside.

“Level five days are absolutely bad for human health. They exacerbate asthmatic attacks, heart disease, disorders of the upper and lower airways and other respiratory conditions”, says Gao Jinming, associate professor in the respiratory disease department of the Peking Union Medical College Hospital.

He says asthma prevalence is also on the rise, partly for this reason. “The environmental risks have changed along with people's lifestyles over the past 10 to 20 years of rapid development.”

Consultants at the college say they experience a significant increase in numbers of patients on level five days. The pollution is one reason for a long-term rise in the workload for asthma and respiratory specialists. “At our centre, the number of patients has increased rapidly in the past 6 years”, says Wang Lianglu, deputy director of the department of allergy. “We only have 10 full-time doctors, but last year, our clinic saw 53 000 patients. I think it is because of lifestyle changes and an improved level of medical care. Patients can now go to a hospital for asthma. In the past, they would have just taken traditional Chinese medicine.”

But pollution is not the only problem. Yin Jia estimates that half of the roughly 25 allergy patients she sees every day have asthma. But at this busiest time of the year for the clinic, the main cause of their attacks is artemisia pollen. This is a growing factor because China is planting billions of trees every year to try to reverse decades of deforestations that have brought the desert to the doorstep of many northern cities. On the August evening when I meet the doctors they tell me they have had one of their busiest days of the year because—despite the unusually glorious blue skies—the pollen count was high.

“We have published a lot of research on this that hasn't come out yet in English. In Europe and America, people do not think that asthma comes from pollen. But our studies in northern China show that this is very very important”, she says. “53% of patients allergic to pollen have asthma. And about 33% have serious asthma.”

None of the doctors The Lancet spoke to were aware of Chinese research into the link between asthma and pollution. But rather than blame this on an official attempt to cover up the health costs of China's development, they said it was because of a lack of funding for clinical trials and the relatively recent introduction of specialist asthma study in medical colleges.

However, this is changing. Zhong Nanshan, director of the China Medical Association and a specialist in respiratory diseases, set up the China Asthma Alliance last year. It has already organised monthly training programmes in hospitals in 26 provincial capitals.

There is also a growing acceptance of treatment methods developed overseas. Imported steroid turbuhalers sold by Astra Zeneca and GlaxoKline lead the market, despite a price of more than 200 yuan (US$25)—or about 5 yuan a day—which is major outgoing in a country where average annual incomes only recently passed the $1000 mark. Here, as in all other areas of Chinese life, there is likely to be a gulf between the rich urban centres on the east coast, and poor farming communities inland. But doctors say more patients could now afford to pay for smoother breathing.

Xu Wenbing, chief of the respiratory department of Peking Union Medical College, says Chinese patients are different from those in the west because they are impatient for a cure. “With asthma there is no cure, only a way to control the symptoms. So, for a long time, many patients, especially those without much money, did not want to buy expensive imported inhalers. And many doctors did not believe they were important. But now, thanks to the rise in living standards, people want a better quality of life so they are more willing to give inhalers a chance. China is now a big market for European pharmaceutical companies.”

Review Air pollution and health Bert Brunekreef, T Holgate. The Lancet 19 October 2002; Volume 360, Issue 9341: Page 1233

Review Environmental health in China: progress towards clean air and safe water Junfeng Zhang, L Mauzerall,Tong Zhu,Song Liang,Majid Ezzati, V Remais. The Lancet 27 March 2010; Volume 375, Issue 9720: Page 1110

Series Public health benefits of strategies to reduce greenhouse-gas emissions: health implications of short-lived greenhouse pollutants Kirk R , Jerrett,H Ross , T Burnett,Vicki Stone, Derwent, W Atkinson, Cohen,Seth B Shonkoff, Krewski,C Arden Pope, J Thun, Thurston. The Lancet 19 December 2009; Volume 374, Issue 9707: Page 2091

Articles Asthma in exercising children exposed to ozone: a cohort study Rob McConnell,Kiros Berhane, Gilliland, J London,Talat Islam,W Gauderman, Avol,Helene G Margolis, M s. The Lancet 2 February 2002; Volume 359, Issue 9304: Page 386

Articles Public-health impact of outdoor and traffic-related air pollution: a European assessment N Künzli,R Kaiser,S Medina,M Studnicka,O Chanel,P Filliger,M Herry,F Horak,V Puybonnieux-Texier,P Quénel,J Schneider,R Seethaler,J-C Vergnaud,H Sommer. The Lancet 2 September 2000; Volume 356, Issue 9232: Page 795

Elsevier Limited. All rights reserved. The Lancet ® is a registered trademark of Elsevier Properties S.A. used under licence.The content on this site is intended for health professionals.