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Common European Plant Pollens Trigger Asthma Emergencies

July 25, 2003

High levels of airborne grass pollens trigger surges in severe asthma attacks that require emergency admission to hospital, suggests research published in Thorax.

The research was carried out between 1995 and 1998 in the Spanish city of Madrid, which has high levels of different types of airborne pollens. Emergency admissions for respiratory illness to one hospital were monitored over this period. Data on circulating pollen levels from trees and plants were collected from 10 monitoring stations, and information on air pollutants, temperature, and humidity was also gathered.

During the study, there were almost 5,000 emergency admissions, half of them children. Emergency admissions rose but did not reach epidemic levels in 1995 and 1997. Pollen levels were relatively low in 1995, while in 1997 persistent heavy rain lessened the amount of circulating pollens, with levels excessive for only eight days.

But in the last two weeks of May 1996 and the first two weeks of June 1998, there were dramatic surges in emergency admissions, reaching epidemic proportions. These coincided with the sudden release of very high levels of pollen from Plantago and Poeceae plant species, both of which are widely distributed throughout Europe.

For Poeceae there was a time lag of three days, and for Plantago, a time lag of two days, before admissions surged by 17% and almost 16%, respectively. Time lags are consistent with the biology of allergens, say the authors. The variations in emergency admissions were independent of the amount of air pollutants, the study showed.

British Medical Journal (BMJ)