The effect of exposure concentration, duration, and ventilation rate on ozone absorption during continuous inhalation exposure

摘要

Ozone (O/sub 3/), a component of urban smog, causes lung irritation upon inhalation and is a significant public health concern. Studies of the effect of O/sub 3/ inhalation on humans typically relate exposure directly to response, with little or no consideration of the actual uptake of O/sub 3/. We hypothesize that duration of exposure, inhaled concentration, and respiratory flow rate are all factors that might affect the uptake of O/sub 3/ in the respiratory tract, causing a nonlinear relationship between exposure and dose. To test this hypothesis, we have designed a high-speed ozone analyzer which is capable of sampling and monitoring breath-by-breath ozone concentration in real-time in exercising individuals. We measured the fraction of inhaled O/sub 3/ which was retained, /spl Lambda/, in eight human subjects during continuous exposure in each of four sessions with O/sub 3/ concentrations of either 0.2 or 0.4 ppm, exposure duration of 30 or 60 min., and target ventilation rates of 20 or 40 Lpm. Our results indicate that O/sub 3/ uptake is proportional to ventilation rate, exposure time, and inhaled concentration such that /spl Lambda/ had a value of 0.86/spl plusmn/0.06 (mean/spl plusmn/SD) for all the subjects we tested.