Global warming behind soaring child asthma

Poor and minority children are likely to develop asthma at worsening rates due to global warming and air pollution, United States environment experts predict.

As the climate gets warmer, allergens such as pollen and mould will flood the air, interacting with urban pollutants such as ozone and soot to fuel an already growing epidemic.

"It is affecting the trees, the moulds, the subsurface organisms," said Dr Paul Epstein of Harvard Medical School's Centre for Health and the Global Environment, one of the authors of the report.

"The combination of air pollutants, aero-allergens, heat waves and unhealthy air masses increasingly associated with a changing climate causes damage to the respiratory systems, particularly of growing children, and these impacts disproportionately affect poor and minority groups in the inner cities," the report says.

It finds that asthma among US preschool children, age 3 to 5, grew 160 per cent between 1980 and 1994.

"This is a real wake-up call for people who think global warming is only going to be a problem way off in the future or that it has no impact on their lives in a meaningful way," said Christine Rogers, a senior research scientist at the Harvard School of Public Health who collaborated with Dr Epstein on the report, as did the American Public Health Association.

"The problem is here today for these children and it is only going to get worse."

Most climate experts agree that the world is becoming steadily warmer, and that human activity is much to blame. Burning fossil fuels such as coal and gas releases carbon dioxide into the air.

The carbon dioxide forms a type of invisible blanket that traps the sun's radiation.

Although average temperatures warm, the effects are not predictable and even. Storms may become more severe and some areas may get colder weather.

The report finds that in some regions, winter is ending weeks earlier, and plants are releasing their pollen earlier, accelerating the hay fever season.

Pollen and fungal spores can worsen asthma, a serious medical condition the symptoms of which include shortness of breath, cough, wheezing, chest pain or tightness.

The Centres for Disease Control and Prevention says nine million US children have been diagnosed with asthma and more than 4 million have had an asthma attack in the past 12 months.

It says 4487 people died from asthma in the US in 2000, most of them adults.

Asthma affects blacks more than any other group and affects 16 per cent of children from poor families as opposed to 11 per cent of children living above the poverty line.

The CDC also says nine million US children were reported with respiratory allergies in 2002.

The Harvard report makes clear links among asthma, allergies and urban air pollution.

"Rising levels of carbon dioxide, in addition to trapping more heat, promote pollen production in plants, increase fungal growth and alter species composition in plant communities by favouring opportunistic weeds like ragweed and poison ivy," the report reads.

"Diesel particulates help deliver and present pollen and mould allergens to the immune system in the lungs."

Dr Epstein said: "The good news is we can do something about this." 'Green' buildings with roof gardens to keep them cool and insulation to keep heat from leaking would help, as would improving public transport and encouraging the use of hybrid vehicles that rely less on fossil fuels.

* NZ has one of the highest asthma rates in the world.

* Surveys show that 10 per cent of adult New Zealanders now take treatments for asthma, and a third of 12- and 13-year-olds have had episodes of wheezing in the past year.

- REUTERS