I'm trying to figure out what kind of air filter is appropriate for my house. My local home warehouse store stocks over a dozen options. The primary difference between them seems to be Microparticle Performance Rating, but there are also differences in material (fiberglass vs. composite), shape (pleated vs. flat) and Minimum Efficiency Reporting Value.

This is a two-part question. First, what factors about my home and/or environment should I consider? For example, I've heard that people who smoke, have pets or live in humid areas may, broadly speaking, want higher quality filters.

Second, once I've figured out what factors to look at, what filter characteristics do they correspond to? To extend my previous example (assuming that smoking really does matter and that MPR is legit, not just a number made up for marketing purposes), is there a minimum MPR value that a smoker should get?

  • I think most manufactures (at least in the US), list the types of things each filter is designed to filter out.
    – Tester101
    Oct 18, 2014 at 16:23
  • Some do, but not all. And I don't know how much faith to put in those lists anyways; their job is as much to upsell me as it is to help me.
    – Pops
    Oct 18, 2014 at 16:35
  • I guess it depends on what you expect from your filter. If you smoke in your house, I can't imagine you're super concerned about air quality. And if you are, you probably shouldn't be relying on your furnace to provide air filtration. Personally I use the the "standard" filters, since I figure the filters only job is to keep crap out of the furnace. If I want to improve the air quality in my house, I'll add a system designed for the purpose.
    – Tester101
    Oct 18, 2014 at 16:50
  • Another point of concern is the pressure drop over the filter. If a too restrictive filter is used, it strains the HVAC fan, causing it to fail. The filters don't seem to say what pressure drop they create at which air flow, but I'd imagine that there would be charts online somewhere.
    – Pigrew
    Oct 18, 2014 at 17:45
  • 1
    @Pigrew, please learn how centrifugal fan loading actually works. You have it exactly backwards (but you have lots of company.) More restriction creates less load on the fan, and less restriction creates more load on the fan. Strange but true.
    – Ecnerwal
    Oct 18, 2014 at 23:51

2 Answers 2


Air filters are intended to:

  1. Protect HVAC equipment.

  2. Mitigate air-quality issues.

The manufacturer will specify requirements necessary for normal equipment service life.

Until there are actual air quality issues, there is no reason to upgrade filters.

Monitoring air quality may be appropriate because some air-quality issues are better mitigated elsewhere from the filter.


You can have the overlook to all the available modes in the market with their specifications.According to the specifications you can have the grading.

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