You can find 3 main types of HVAC air purifiers:
High-MERV media filter
High-MERV filters act like a regular air filter to remove contaminants as they get pulled into your HVAC system. But high-MERV filters are much more dense, so they can remove pollutants as fine as bacteria and tobacco smoke.
MERV (Minimum Efficiency Reporting Value) is a rating that measures how efficiently a filter can remove contaminants from your home. The higher the MERV rating (1-20), the finer the particles the filter can remove. The highest-rated filter you can get is a HEPA (high-efficiency particulate air) filter, which has a MERV rating of 17-20.
We recommend the following high-MERV media filters:
Electronic/Ionic air purifier
Ionic air purifiers, also called "electronic air cleaners", are media filters that have an electronically charged metal layer. When particles pass through the metal layer, they become positively charged and cling to the media filter.
We recommend the following electronic air cleaners: