The next step past HEPA (for consumers) is activated carbon/charcoal [0]. Most higher-end air purifiers have this included, which helps with filtering gases. I

The next step past HEPA (for consumers) is activated carbon/charcoal [0]. Most higher-end air purifiers have this included, which helps with filtering gases. I personally have an Airmega [1] and have been very happy with it. It was particularly helpful when there was smoke from fires in NorCal -- I had far better air quality at home than at the office. [0] https://en.wikipedia.org/wiki/Carbon_filtering https://en.wikipedia.org/wiki/Carbon_filtering [1] https://www.cowaymega.com/product/coway-airmega-400s-white/ https://www.cowaymega.com/product/coway-airmega-400s-white/