Increased ambient grass pollen associated with increased risk of childhood asthma ED visit

Australian researchers presented what they say is the first study to establish a clear relationship between increased risk of childhood asthma emergency department (ED) attendance and increasing levels of ambient grass pollen below 20 grains/m3, independent of thunderstorm-associated asthma.

Dr. Bircan Erbas of La Trobe University in Melbourne and colleagues at several other institutions conducted a short-time series ecological study of ED presentations for asthma among children in Melbourne, Victoria, and grass pollen, meteorological, and air quality measurements recorded during the selected 2003 period. A semi-parametric Poisson regression model was used to examine the dose-response associations between daily grass pollen levels and mean daily ED attendances for asthma among children.

Following data analysis, a smoothed plot suggested a dose-response association. As ambient grass pollen increased to about 19 grains/m3 the same-day risk of childhood ED presentations also increased (P<0.001). Grass pollen levels were also associated with an increased risk in asthma ED presentations on the following day (P<0.001).

Lower levels of pollen may contribute to asthma symptoms, so the limits of the pollen season may need to be reviewed and this in turn could affect the timing of immunotherapy, Dr. Erbas and colleagues concluded.