There are 300 million asthma sufferers in the world and that figure is expected to jump to 400 million in 20 years, medical experts said Tuesday.
In many countries, the prevalence of asthma is rising 20 percent to 50 percent every 10 years, said specialists at the 4th World Asthma Meeting in Bangkok.
Speaking at a news conference, asthma specialists said the disease needs greater attention because of its high human and economic costs.
The newly collected data was contained in a report released by the World Health Organization and the Global Initiative for Asthma to coincide with the meeting.
The report, "The Global Burden of Asthma," warned that "the rate of asthma increases as communities adopt Western lifestyles and become urbanized." It said asthma is on the increase among adults as well as children.
Experts at the conference said they are baffled by what causes asthma — a common chronic lung condition that causes the inflammation of airways and makes breathing difficult — or why increases in asthma seem to go hand in hand with economic development.
"I wish it was that easy to plot what it is about urbanization and affluence that goes into it. In fact, we simply don't know," said Richard Beasley from the Medical Research Institute of New Zealand.
One theory argues that children now are not exposed to enough germs in early life to mature their immune systems, and therefore are less able to handle the irritants that contribute to the condition.
Other ideas link the increase simply to more people living in cities, or to processed foods in the modern diet. Air pollution has often been blamed.