Higher levels of air pollution may be linked to a heightened risk of developing oral cancer, which includes cancers of the lips, tongue, cheeks, floor of the mouth, hard and soft palate, a study has found.

While mouth cancers have been associated with smoking, drinking, human papillomavirus, and the chewing of betel quid ("paan"), the study added to this list increased levels of fine particulate matter (PM2.5) and to lesser extent, ozone.