Do HEPA air filters serve any health benefit?

Question

I have been researching particulate matter pollution and air filters. I read about HEPA air filters and that they can capture over 99% of particles in the air, including allergens. I was thinking that might mean HEPA air filters could really help with indoor air pollution and keep people healthier, especially in locations with high particulate matter, and especially in homes with fuel-based heating in the home. I assume this should help with asthma, allergies, and may help prevent the effects of particulate matter. But I don't see any actual studies that show this when I google the topic, I feel almost all the results are trying to sell me an air filter instead of giving a scientific explanation of the benefits.

Do HEPA air filters have a statistically significant impact on health?

Answer 1

I found three well conducted (randomized trial) studies on this topic. Synthesis seems to be that HEPA results to significant reduction in the particulate matter in the air but the objective effects on health remains to be shown.

Study 1:

HEPA filtration resulted to better air quality. In subjects exposed to traffic-related matter, use of HEPA resulted to lower level of C-reactive protein indicating less intensive systemic inflammation. No effect was when examining subjects exposed to woodsmoke matter.

Study 2:

Subjects were exposed to traffic-realted particles and use of HEPA filtration had no effect on blood pressure, level of C-reactive protein, fibrinogen or tumor necrosis factor alpha-receptor.

Study 3:

Investigators examined subjects exposed to "regular" indoor air. HEPA filtration had no effect on microvascular and lung function or the biomarkers of systemic inflammation.

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My personal opinion is that I strongly believe that use of HEPA filtration has beneficial health effects IF one is subjected to particulate-matter (like traffic induced). The theory is quite solid: we reduce the bad, potentially carcinogenic particulate matter in the air which we breath daily.

As so, it is very reasonable to assume that intervention has it´s advantages. What they are, remains to be shown. It should be noted that these studies mentioned investigate only the short term effects. It reasonable to assume that long-term effects are evident (lung cancer, chronic bronchitis, COPD etc.)

Answer 2

Not knowing about HETA air filters some general information: Small particles in air may cause cancer or other lung diseases, but preferably when inhaled in large amounts for a long time(>10 years). In regions of low small-particle-pollution you won't need any air filter, in regions with high pollution this may cause health damage. (http://www.who.int/mediacentre/factsheets/fs313/en/) In a highly polluted area (like the air is "grey") a filter wouldn't be a bad idea, I would use one. In a low polluted area it won't be too effective. Also, as I assume the place you use it is not air-thight it wont have full effect. Assuming you are 12h/day at home I would be impressed if it has more that 20%-30% effect on your day-intake of PM.

So to answer you question (I did not find numbers, but look at the WHO link above): It may have an significant positive impact to your health in high polluted regions. Many (non published) studies tried to prove that things like this work in low polluted regions but never got significant.