Cheap charcoal air filters offer improvements to in-vehicle air quality

Credit: Dan Gold/Unsplash A cheap charcoal air filter can reduce nitrogen dioxide (NO2) inside vehicles by as much as 90%, compared to levels outside the vehicle. Research presented in a report by WM Air, the West Midlands Air Quality Improvement Programme at the University of Birmingham, shows that charcoal filters, which costs around £10-£20, can effectively remove 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 activated carbon filters, in contrast, remove NO₂ through a process called adsorption, in which the NO₂ reacts with the carbon to stick to the surface area of the filter.