Cleaning up the air inside our vehicles
A great deal of attention is focused on outdoor air quality, but significant health risks arise from poor air quality in enclosed spaces. In addition to their homes and workplaces, people are spending an increasing amount of time in vehicles, including cars, buses, trains, aircraft, etc. In response, the GROWTH Programme charged the CLEANRCAB project consortium with developing an in-vehicle air quality management system. The VTT Technical Research Centre of Finland was assigned the task of evaluating different technologies for removing gaseous and particulate pollutants from the air inside vehicles. They selected different types of filters and precipitators and subjected them to a battery of tests in the laboratory. VTT found that while electrified fibrous filters worked well in dry air, their efficiency declines considerably in humid conditions. They next turned to electret filters, whose permanent electric charge helps them collect both charged and uncharged particles. When combined with a corona charger, the electret filter demonstrated admirable performance characteristics. However, it was unable to manage cigarette smoke, a common culprit of poor indoor air quality. The best results were achieved with electrostatic precipitators. VTT tested several commercially available models as well as two small-scale prototypes it developed. High particle removal rates were achieved without major losses in pressure, even by the compact versions. The next step for VTT and its CLEANRCAB partners is to analyse how best to incorporate an electrostatic precipitator into vehicular air conditioning systems.
