With many of us being forced to spend more time indoors due to work-from-home policies and digital classrooms, it is important to take the quality of air inside our homes more seriously than before. According to the World Health Organisation (WHO) fact sheet, indoor air pollution is one of the main reasons for respiratory diseases and premature deaths in developing countries, contributing to nearly 40 lakh deaths annually. In most cases, the culprit is particulate matter 2.5 (PM2.5)—tiny invisible pollutants that hang in the air for a long period and are many times smaller than the diameter of the human hair. PM2.5 can settle deep in the lungs, causing respiratory illnesses and even cancer.