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The effect of repeated exposures to ambient air levels of ozone on the late phase response to allergen in subjects with asthma and allergic rhinitis


The aim of our study was to reveal whether ambient air levels of ozone exert an effect on bronchial allergen responsiveness the day after exposure, and whether repeated ozone exposures lead to effects which are different from those of single exposures. To quantify the

response, we assessed lung function and airway responsiveness to methacholine and allergen, and in addition potential cellular and biochemical effects by the method of induced sputum and the analysis of exhaled NO and H2O2. We included 11 subjects with allergic asthma, 23 subjects with allergic rhinitis, and 5 subjects with a positive skin prick test to allergens without a history of asthma or rhinitis. Subjects underwent either a single exposures to filtered air, 125 ppb or 250 ppb ozone, as well as four repeated exposures to 125 ppb ozone; the day after (the last) exposure, allergen challenges and sputum induction were performed. The effect on lung function as well as the effects on inflammatory parameters showed large interindividual differences. After single exposure with 250 ppb and after the repeated exposures with 125 ppb ozone we observed the largest decline in FEV1 during early phase response and to a lower extent during late phase response. Corresponding changes in induced sputum were characterized by increases in the proportions of granulocytes and sputum fluid-phase parameters such as LDH. Increased levels of NO in exhaled air could be deteccted after exposure to filtered air and 125 ppb ozone, as well as during late phase response. The described effects were most pronounced in subjects with rhinitis. In adddition we found an association between the extent of ozone induced enhancement of the allergic response and the concentration of total and specific IgE in blood. Our data demonstrate that repeated exposures with high ambient concentration of ozone are able to enhance the response to allergen in subjects with existing allergic airway reactions.


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