Previously air purifiers were discussed by the group.  I had commented that MCS/EHS doctor Grace Ziem on her intake Environmental Questionnaire asks patients about their usage of air filters.  It appears that the filters which are harmful are the ones which generate ozone such as electrostatic/ionizing filters and ozone generators and not the ones that generate only negative ions.

Here's a current list of the potentially hazardous ozone generators sold as air purifiers:

https://www.arb.ca.gov/research/indoor/o3g-list.htm

An EPA pdf (the ones who fail to monitor environmental EMF) on unhealthy ozone levels:

https://www3.epa.gov/airnow/ozone-c.pdf

bonnie