The effects of bedroom air quality on sleep and next-day performance were examined in two field-intervention experiments in single-occupancy student dormitory rooms. The occupants, half of them women, could adjust an electric heater to maintain thermal comfort but they experienced two bedroom ventilation conditions, each maintained for 1 week, in balanced order. In the initial pilot experiment (N = 14), bedroom ventilation was changed by opening a window (the resulting average CO 2 level was 2585 or 660 ppm). In the second experiment (N = 16), an inaudible fan in the air intake vent was either disabled or operated whenever CO 2 levels exceeded 900 ppm (the resulting average CO 2 level was 2395 or 835 ppm). Bedroom air temperatures varied over a wide range but did not differ between ventilation conditions. Sleep was assessed from movement data recorded on wristwatch-type actigraphs and subjects reported their perceptions and their well-being each morning using online questionnaires. Two tests of next-day mental performance were applied. Objectively measured sleep quality and the perceived freshness of bedroom air improved significantly when the CO 2 level was lower, as did next-day reported sleepiness and ability to concentrate and the subjects' performance of a test of logical thinking. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.[The copyright line for this article was changed on 17 November 2015 after original online publication]. Practical ImplicationsIt is often possible to select bedroom air temperature at will, but in bedrooms with the window closed for energy conservation and the internal door closed for privacy, the effective ventilation rate is often so poor that CO 2 levels routinely exceed 2500 ppm. This occurs in cold or temperate regions and certainly also in air-conditioned bedrooms in hot-humid regions. This field experiment was the first to examine how bedroom air quality affects sleep and next-day performance. It was shown that both can be significantly improved by increasing the clean outdoor air supply rate in bedrooms. In cold and temperate regions, this could be achieved at low energy cost and with no loss of privacy by installing outdoor air inlets with counter-flow heat exchange in each bedroom, the air exchange being controlled by the CO 2 level in the exhaust flow. However, it should be remembered that in some areas noise attenuation and pollution removal technology might then become necessary and that in such areas, the simpler solution of opening a window might have a negative effect on sleep.

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Operating a gas-phase adsorption (GPA) air purifier unit in the recirculated air in a simulated airplane cabin provided a clear and consistent advantage for passengers and crew that became increasingly apparent at longer flight times. This finding indicates that the expense of undertaking duly blinded field trials on revenue flights would be justified.