Now that the California fires are raging, it may be time to bring up a few additional reasons why HEPA filters make a lot of sense. I don’t know how much this changes the cost-benefit analysis, but I think it is important to take into account:
1) Right now the PM2.5 outside my apartment is 230. Inside it’s 40. A week ago the PM2.5 was 100, and inside it was 8. By having a HEPA filter inside, I’ve been seeing reductions of PM2.5 between 80% and 90%. I also saw this two years ago, and it’s been a rather consistent pattern.
2) The idea that non-linearity makes the benefits strictly less than linearity, and therefore that assuming linearity will lead to an optimistic assessment is questionable. In particular, I grant this is true with “diminishing returns” curves. But it’s not true with S-shaped curves. So, if it is true that the negative health effects of PM2.5 are concave below 20 and convex above 20, then the assumption of linearity will lead to an underestimation of the positive health benefits of HEPA filters for places with relatively clean air.
3) As a special case of (2), I would expect that giving your lungs “time to breath” (so to speak) might be really good to let them heal, and also allow your cardiovascular system to recover from inflammation. So there may be some extra benefits to being in places that have close to 0PM2.5 for at least some periods of time. And lastly,
4) I do think that the case for massively reducing the economic cost of HEPA filters should be considered more thoroughly. If subsidized at the governmental level, how cheap could these filters become? My suspicion is that they can become extremely cheap, turning them into a utility.
Thank you for the analysis and for bringing this topic to attention of EAs (whose saved micromorts may, well, ultimately have compounding benefits for all). Cheers!
Now that the California fires are raging, it may be time to bring up a few additional reasons why HEPA filters make a lot of sense. I don’t know how much this changes the cost-benefit analysis, but I think it is important to take into account:
1) Right now the PM2.5 outside my apartment is 230. Inside it’s 40. A week ago the PM2.5 was 100, and inside it was 8. By having a HEPA filter inside, I’ve been seeing reductions of PM2.5 between 80% and 90%. I also saw this two years ago, and it’s been a rather consistent pattern.
2) The idea that non-linearity makes the benefits strictly less than linearity, and therefore that assuming linearity will lead to an optimistic assessment is questionable. In particular, I grant this is true with “diminishing returns” curves. But it’s not true with S-shaped curves. So, if it is true that the negative health effects of PM2.5 are concave below 20 and convex above 20, then the assumption of linearity will lead to an underestimation of the positive health benefits of HEPA filters for places with relatively clean air.
3) As a special case of (2), I would expect that giving your lungs “time to breath” (so to speak) might be really good to let them heal, and also allow your cardiovascular system to recover from inflammation. So there may be some extra benefits to being in places that have close to 0PM2.5 for at least some periods of time. And lastly,
4) I do think that the case for massively reducing the economic cost of HEPA filters should be considered more thoroughly. If subsidized at the governmental level, how cheap could these filters become? My suspicion is that they can become extremely cheap, turning them into a utility.
Thank you for the analysis and for bringing this topic to attention of EAs (whose saved micromorts may, well, ultimately have compounding benefits for all). Cheers!