Table 3: Association between pediatric asthma and aeroallergens and other exposures.

Source/yearOutdoor variablesAge groupSample sizeRegionStudy designAssessment methodFindings and limits

Asthma symptoms
Dellavalle et al., 2012Tree, grass, weed, and all-type pollen4–12 years430Northeast, USCross-sectional/adjusted for covariatesQuestionnaire, daily diary, allergen-specific IgE panel for grass and ragweed; pollen and exposure Weed pollen at low levels (6–9 grains/m3) was associated with shortness of breath, chest tightness, rescue medication use, wheeze, and persistent cough; grass pollen (≥2 grains/m3) was associated with wheeze, night symptoms, shortness of breath, and persistent cough. Limit: the study did not investigate the effect of tree pollen on sensitized children

Asthma-related symptoms and care utlization
Jariwala et al., 2011Tree pollen, ragweed, mugwort0–18 years; and adults52 (weekly mean ED visits)Northeast, USCross-sectional/adjusted for covariatesED visit data (ICD-9-CM codes), hospitalization data, pollen count (particles per cubic meter)ED visits highly correlated with tree pollen ( = 0.90, = 0.03) during Spring (March–May). No statistical association of pollen (i.e., ragweed, mugwort) during summer or fall. Limit: data limited to seven major hospitals in New York City, borough of the Bronx.

Asthma sensitivity tests
Sheehan et al., 2010Trees (birch, oak, maple, elm), grass, ragweed mix,0–21 years1,394Northeast, USCross-sectional/adjusted for covariatesSkin prick testing databaseGrass and ragweed were least common sensitizers in younger children, with rates of 1.0% (0–2 years) and 2.8% (2–4 years) for grass and 1.0% (0–2 years) and 5.7% (2–4 years) for ragweed. The rates were higher among those aged 10–12 with rates of 28.8% for grass and 34.2% for ragweed. Trees were common outdoor exposure sensitizers in all age groups. Limit: given the retrospective not all patients received the same testing

NHANES: National Health and Nutrition Examination Survey. Note. (a) used modeling to estimate ambient pollen exposure.