I had no idea about this until I read this article yesterday, which details the worst kinds of air pollution that we're exposed to during a normal working day. Scented candles and incense are both air pollutants! Just thought I'd share that, as I feel like particularly candles are in almost everyone's home these days www.thetimes.co.uk/edition/news/air-pollution-snuff-out-scented-candles-and-avoid-tube-how-to-clean-your-air-gps5l9s8r