Gas sensors for improved air quality in transportation

There is increasing concern about the quality of the air breathed by passengers in the cabins of various different forms of transport. In the case of motor vehicles, the concentration of air pollutants in passenger cabins, particularly in the urban environment, is significantly higher (by two to three times) than the nominal value outside the cabin. Aircraft draw in fresh air from outside the cabin. On the ground the same concentration mechanism as motor vehicles applies. At altitude the major problem is the relatively high concentration of ozone. In cruise liners the problem is analogous to large hotels and casinos: efficient air-conditioning requires recirculation of the air and pollutant concentrations build up over time. Strategies are being developed to mitigate these effects, and for optimal operation most require the use of low cost gas sensors for monitoring and/or control. This article describes what can be achieved with mixed-metal oxide semiconductor gas sensors.