Formaldehyde is one of the most pervasive indoor air pollutants — found in furniture, flooring, textiles, paints, and building materials, as well as in mortuaries, medical and histology laboratories, and hundreds of industrial processes. Classified as a human carcinogen, it poses particular risks to those with asthma or chemical sensitivity, and is subject to strict COSHH workplace exposure limits. Standalone air purifiers with specialist aldehyde filtration media offer an effective and practical means of control.