Pollen exposure and hospitalization due to asthma exacerbations: daily time series in a European city
Nicholas J. Osborne & Ian Alcock & Benedict . Wheeler & Shakoor Hajat

 

This study applied an ecological time series analysis to examine associations between atmospheric concentrations of different pollen types and the risk of hospitalization for asthma

in London from 2005 to 2011. The analysis examined short-term associations between daily pollen counts and hospital admissions in the presence of seasonal and long-term patterns, and allowed for
time lags between exposure and admission. Models were adjusted for temperature, precipitation, humidity, day of week, and air pollutants. Analyses revealed an association between
daily counts (continuous) of grass pollen and adult hospital admissions for asthma in London, with a 4–5-day lag. When grass pollen concentrations were categorized into Met Office
pollen ‘alert’ levels, ‘very high’ days (vs. ‘low’) were associated with increased admissions 2–5 days later, peaking at an
incidence rate ratio of 1.46 (95%, CI 1.20–1.78) at 3 days.
Increased admissions were also associated with ‘high’ versus ‘low’ pollen days at a 3-day lag. Results from tree pollen
models were inconclusive and likely to have been affected by the shorter pollen seasons and consequent limited number of observation days with higher tree pollen concentrations.
Future reductions in asthma hospitalizations may be achieved by better understanding of environmental risks, informing improved
alert systems and supporting patients to take preventive measures.