Charcoal air filters improve in-vehicle air quality

The report by WM Air, the West Midlands Air Quality Improvement Programme at Birmingham University, shows that charcoal filters, which cost around £10-£20, can effectively remove nitrogen dioxide (NO2) from the air within vehicle cabins.

NO2 is a common air pollutant that can aggravate diseases such as asthma and increase the risks of respiratory infections. Traffic emissions are a dominant source of NO2, and so road users inside vehicles are exposed as air circulates into vehicle cabins from outside through open windows and ventilation systems.

While ventilation systems do currently filter air, this is typically via a pollen filter. These prevent tiny particles and pollen getting inside the vehicle, but they have little effect on gases such as NO2, the Birmingham team explained.

The activated carbon filters, in contrast, remove NO2 through adsorption, in which the NO2 reacts with the carbon to stick to the surface area of the filter.

According to the team, as with the pollen filter, the effectiveness of the carbon filter decreases over time, meaning it should be replaced regularly when the vehicle is serviced.