Children With Food Allergy Are at Risk of Lower Lung Function on High-Pollen Days.

BACKGROUND:Grass pollen exposure is a risk factor for childhood asthma hospital attendances. However, its short-term influence on lung function, especially among those with other allergic conditions, has been less well-studied. OBJECTIVE:To investigate this association in a population-based sample of children. METHODS:Within the HealthNuts cohort, 641 children performed spirometry during the grass pollen season. Grass pollen concentration was considered on the day of testing (lag 0), up to 3 days before (lag 1-lag 3), and cumulatively (lag 0-3). We used linear regression to assess the relevant associations and examined potential interactions with current asthma, hay fever or eczema, and food allergy. RESULTS:Associations were observed only in children with allergic disease (P value for interaction ≤ 0.1). In children with food allergy, grass pollen concentration was associated with a lower ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC) and lower mid-forced expiratory flows (FEF25%-75%) at all lags (eg, at lag 2, FEV1/FVC z-score = -0.50 [95% CI -0.80 to -0.20] and FEF25%--75% z-score = -0.40 [-0.60 to -0.04] per 20 grains/m3 pollen increase), and increased bronchodilator responsiveness (BDR) at lag 2 and lag 3 (eg, at lag 2, BDR = (31 [95% CI -0.005 to 62] mL). In children with current asthma, increasing grass pollen concentration was associated with lower FEF25%-75% and increased BDR, whereas children with current hay fever or eczema had increased BDR only. CONCLUSIONS:A proactive approach needs to be enforced to manage susceptible children, especially those with food allergy, before high-grass pollen days.