Q: I recently became a father (first baby) and would love to provide the best possible environment for my son. As I live in condominium, I have a lot of neighbors who smoke cigarettes. I have talked to them about it, yet they continue to smoke anyways. So, I thought I needed a air purifier. Is there any air purifier that can eliminate cigarette smoke particles? If there aren’t any air purifiers that can eliminate cigarette smoke particles, are you aware of any way to do so?

A: Hi! I’m the co-author of our air purifier guide. This a is a great question—and the answer is a bit complicated. Congrats, by the way, and well done on the effort to provide a healthy environment for the baby.

Up front, you should know that no air purifier completely eliminates particles in the air. Under lab conditions, HEPA filters (like those we tested) remove 99.97 percent of the hardest-to-filter particles—but in the real world, new particles are constantly entering your home through windows, doors, and vents.

That said, a HEPA filter will do a very good job of eliminating the cigarette-smoke particles it encounters. That’s because the majority of these particles fall in the 0.1 to 0.5 micron range, which HEPA filters are exceptionally good at capturing. Under real-world conditions, a good purifier (like our pick, the Coway Mighty) can continuously reduce particulate pollution in a room by almost 90 percent.

Two caveats: There’s some evidence that cigarette smoke also contains ultrafine particles that can pass through HEPA filters. And cigarettes also produce volatile organic compounds, or VOCs, and they’re so small that HEPA filters don’t capture them at all. To remove these VOCs, which are partially responsible for the smoky odor—and some of which are quite unhealthy—you need a filter that contains a chemical adsorbent, usually activated charcoal, as well as a HEPA filter for the larger smoke particles. [To clarify, prompted by reader Ben Gold”s comment below: The activated charcoal/carbon filter must weigh 5 pounds or more to meaningfully remove VOCs. Few filters, including those of our pick, the Coway Mighty, and our runner-up, the Winix 5500-2, contain more than a few ounces of charcoal.] The only one we recommend that contains both types of filter is the Austin Air Healthmate HM-400. You’ll find it’s substantially more expensive than the Coway, but for the money, you do get a truly different level of filtration performance.

Bottom line: A HEPA-rated air purifier will significantly reduce the cigarette-smoke particles in your home, and a HEPA purifier with a chemical adsorbent will significantly reduce those smaller VOCs as well. But the only way to eliminate the smoke in your home is to find a way to avoid exposure in the first place.

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