The most important parameters that influence the air quality in vehicles are the choice of cabin air filter and the air quality outside the vehicle. Real-life driving test methods for measurement in traffic environments developed in AQIFOR project showed repeatable differences between the reduction efficiency of the various cabin air filters in the car ventilation systems. Additional parameters that affected the reduction efficiency for air pollutants in the vehicle were ventilation speed and degree of air recirculation in the ventilation. Different air pollutants are affected differently. All filters tested purified air from particles; the reduction efficiency for PM2.5 was from 40% to over 80% for different filters, particles in the size range 10 - 600 nm were more difficult to clean than larger particles. Filters containing active carbon also purified the air from NO2; reduction efficiency showed similar pattern to reduction efficiency for particles. Sampling for VOC and PAH showed that volatiles are not purified by filters, but the less volatile species are effectively reduced. The project also investigated occupational exposure of professional drivers to air pollution in both passenger cars and trucks. The results showed that the drivers' exposure to benzo (a) pyrene, 1,3-butadiene and benzene was low, well below the working environment limit values.
The most important parameters that influence the air quality in vehicles are the choice of cabin air filter and the air quality outside the vehicle, ventilation speed and degree of air recirculation are additional parameters that affect. Real-life-driving based test methods for measurement in traffic environments developed in AQIFOR showed repeatable differences between the reduction efficiency of the various air filters of the ventilation systems. All purified air from particles, filters containing activated carbon also removed NO2. Sampling for VOC and PAH showed that volatiles are not purified by filters while the less volatile species are effectively reduced.