Experimental exposures of asthmatic and healthy humans to nitrogen dioxide and nitrous acid

摘要

Ph.D.-thesis based on three human exposure studies, two with nitrogen dioxide (NO(sub 2)) and one with nitrous acid (HONO) with assessments of airway responses and a meta-analysis based on the best (defined by size and design) human exposure studies with NO(sub 2) published 1980-1989. A study with healthy and asthmatic subjects simulated possible NO(sub 2)-exposures in a kitchen during the use of a gas stove. Another study where healthy non-smokers were monitored for 24 hours simulated the maximally allowed NO(sub 2)-exposure during a working day. A third study, in which only healthy subjects participated, evaluated possible airway effects of HONO. HONO may arise from a reaction between NO(sub 2) and humidity on surfaces. In summary the conclusions of the studies have been that short term NO(sub 2) exposures up to the highest recorded in kitchens is unlikely to result directly in decreased pulmonary function neither for healthy nor for asthmatic subjects. However, the meta-analysis indicated that NO(sub 2) in concentrations found in real exposure situations could cause increased bronchial reactivity. For asthmatics this may occur at a concentration found in unventilated kitchens during the used of a gas stove. For healthy subjects it may occur at NO(sub 2) concentrations near the maximally allowed NO(sub 2)-level for the working environment. NO(sub 2) exposures of the latter magnitude appears to cause delayed reactions in the anti-oxidative defence system of the body and possible also in alveolar permeability. For healthy subjects it is unlikely that HONO formed in the environment from NO(sub 2) should elicit airway responses. (au) (78 refs.)