Air purifiers are a great way to cut down on indoor contaminants, but they're not always budget-friendly. Here are some inexpensive alternatives.

The main element of the filter is 25 kg of activated charcoal ... available Fram CA3281. Another air cleaner element (Fram CA3333) makes sure no loose charcoal dust is expelled from the filter.

3D-printable parts and an easy-to-fill chamber for bulk-activated carbon make this recirculating air filter for VOCs a smart, space-saving design. A Nevermore filter sits inside the build chamber ...

MacMurray advises placing a small air purifier, like the Levoit Core Mini ($50) in the offending closet. If you don’t have an outlet in there, hanging activated charcoal bags inside can help too.