Such research basically shows
Such research basically shows the average impact of exposure to different pollutants. Different individuals experience vastly different exposure depending on their circumstances. A given pollutant can have a certain level of impact on an individual, within different communities, and globally. Depending on whether you are looking at the global impact, impact within a specific community or cohort of people, the average impact most often differs from the global impact of that pollutant. PM2.5 leads to premature deaths and drives more disease very unequally around the world and even within small communities depending on the exposure of each individual and the health status and vulnerability of each individual. This article addresses the problem of indoor air pollution and is aimed at individuals making decisions regarding remediation of their exposure to indoor air pollutants. PM2.5 is a very important air pollutant globally, but for certain individuals, it may be radon, or VOCs, etc. You need to assess your specific indoor air quality situation and determine if exposure to PM2.5 indoors is an issue for your home. If wildfires are common around where you live, or you live close to a motorway, for example, PM2.5 is likely going to be an important indoor air pollutant for you to focus on.

Sources of PM2.5 include:
Sources of PM2.5 include:
1) exhaust of vehicles and small internal-combustion-engine-powered appliances, such as lawn mowers, snow and leaf blowers, etc.; infiltration of outdoor air indoors brings PM2.5 particles originating from exhaust, industry, tire and brake wear and tear, other combustion sources, and from various natural sources (wildfires, vegetation, dust, volcanic activity, etc.) into indoor spaces;
2) any indoor burning (candles, smoking, incense);
3) consumer products that are sprayed (sunscreen, deodorant, etc.);
4) cooking.

This is an incomplete list.

The lung cancer number/risk associated with it really is a purely extrapolated guess based on a Hypothesis of LNT (Linear No-Threshold) which still is controversial and not proven.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3834742/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2663584/

I do not know if I would go with a hormesis effect (hypothesis) but you could make an argument that it is just as valid and should be tested.

These risk asssements is all based on very conservative assessment of ionizing radiation that still has not been proven.

That said, a guess of a million lung cancer cases due to low-level radon radiation is as accurate as a guess that low-level radiation may have health benefits and has saved lives.

Air bypassing filters is a
Air bypassing filters is a major issue that occurs with relatively small leaks/bypass that causes major issues in time.

Thanks, David.  I guess I

Thanks, David.  I guess I missed that article when it came out a couple of years ago.

Does Ozone not help eliminate
Does Ozone not help eliminate other VOC’s? With a half life of 45 minutes at 72 degrees and required to be produced by sunlight or electrical arcing, aren’t indoor ozone levels lower than outdoor ozone levels?

https://bit.ly/2PPh6PI

Dan, yes, my next article

Dan, yes, my next article will be all about the problems leading to poor filtration, like bypass.

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Roy, I think you may be

Roy, I think you may be looking at this the wrong way.  I’ll have to dig into the research behind the chart to know for sure, but I don’t think it’s going to be based on a certain PM2.5 level.  One person might be affected by lower level than another.  It’s the DALYs that matter, and I think that’s what tells you how bad PM2.5 really is. 

The harder question is whether the numbers in the chart come from correlations or from causal relations.  I’ll see what I can find.