Ozone levels in passenger cabins of commercial aircraft on North American and transoceanic routes

Ozone levels in airplane cabins, and factors that influence them, were studied on northern hemisphere commercial passenger flights on domestic U.S., transatlantic, and transpacific routes. Real-time data from 76 flights were collected in 2006–2007 with a battery-powered UV photometric monitor. Sample mean ozone level, peak-hour ozone level, and flight-integrated ozone exposures were highly variable across domestic segments (N = 68), with ranges of <1.5 to 146 parts per billion by volume (ppbv), 3−275 ppbv, and <1.5 to 488 ppbv-hour, respectively. On planes equipped with ozone catalysts, the mean peak-hour ozone level (4.7 ppbv, N = 22) was substantially lower than on planes not equipped with catalysts (47 ppbv, N = 46). Peak-hour ozone levels on eight transoceanic flight segments, all on planes equipped with ozone catalysts, were in the range <1.5 to 58 ppbv. Seasonal variation on domestic routes without converters is reasonably modeled by a sinusoidal curve that predicts peak-hour levels to be approximately 70 ppbv higher in Feb−March than in Aug−Sept. The temporal trend is broadly consistent with expectations, given the seasonal cycle in tropopause height. Episodically elevated (>100 ppbv) ozone levels on domestic flights were associated with winter−spring storms that are linked to enhanced exchange between the lower stratosphere and the upper troposphere.