The body of evidence on pollen-related asthma exacerbations in children in the climate change era

Abstract

TPS 752: Respiratory effects and allergies, Exhibition Hall, Ground floor, August 27, 2019, 3:00 PM - 4:30 PM Background/Aim: Climate change poses a risk to both respiratory and children’s health. Flowering is starting earlier, pollen species moving from north to southern regions, and pollens in urban areas becoming more allergenic due to air pollution. The respiratory health of the most vulnerable such as children need to be protected from these multiple risks. We quantified the health burden related to pollen in children with asthma, considering the potential interaction with air pollution. Methods: A systematic literature review was carried out using both indexed and free terms in Embase and Medline (Ovid) since 1999 to date. We included studies evaluating the short-term effect of pollens on asthma hospital admissions (HA)/emergency visits (EV) or asthma symptoms in time series/case-crossover or panel study designs and long-term effects in birth cohort studies. When number of effect estimates was 3 or more a meta-analysis was done with evaluation of heterogeneity and publication bias. Risk of bias is assessed using instruments for non-randomized studies (ROBINS-I). Results: A total of 21 studies was included. Birth cohorts provide contrasting results about exposure to pollens at birth and development of asthma or symptoms later in life. For grass pollen, the Mantel-Haenszel pooled estimate for the risk of asthma HA or EV is 1.9% (95%CI 1.2-2.6 for 10 grains/cbm; Higgins I2=14.9%, p-value Egger’s test=0.70) (lag 0 to 6 days). A smaller number of studies evaluated weed (e.g. Ambrosia) and tree families. Three studies provided mixed results on interaction between pollens and air pollution. Risk of bias assessment is ongoing. Conclusions: There is a growing body of evidence on adverse effects of pollens on asthmatic children, even at age younger than 4. Cities need to become resilient to climate, urban spaces (e.g. green spaces) well managed, air quality improved and vulnerable individuals such as children protected from all these risks.