An epidemiological approach investigating respiratory disease response in sensitive individuals to indoor and outdoor pollen exposure in Tucson, Arizona

We conducted this study during the early spring to demonstrate direct response between increases in atmospheric pollen concentrations and symptom prevalence in a general population. We examined pollen concentrations indoors, outdoors and regionally in 31 households with similar background vegetation, pollen concentration, TSP and pollulant gas levels. Indoor pollen concentrations were low but persistent (X=16 grains/m³ air); local outdoor concentrations were 3 times greater. Regional daily mean pollen values of grasses, ragweed, mulberry and total pollen were compared with symptom scores using X² contingency tests. We obtained daily symptom scores and measures of peak expiratory flow from 121 individuals characterized as «normal», «atopic» or «peak flow responsive». In atopic individuals, prevalence of nasal symptoms increased with pollen concentration increases for ragweed, mulberry and total pollen exposure. No significant response was found with spring grasses whose atmospheric pollen concentration was limited in the selected cluster. Decrease of lung function in the peak flow responsive population was found associated with mulberry pollen only. The small pollen grain size may result in greater tracheo-bronchial deposition.