Indoor air filtration capable of reducing PM2.5 particles increases life expectancy and experts argue should change standards to require better filtration.
In general, the filters in ventilation equipment are primarily designed to protect the equipment and not to make the air better for those who breathe. There are exceptions, such as the F7 filters in the Passive House-level MVHR systems, but they’re pretty rare. It is understood that breathing fine particles doesn’t kill people immediately but it reduces life span across populations. On this basis the authors of a recent ASHRAE Journal article argue that it is valid to use WHO studies on disability-adjusted life year (DALY) to compare the cost of superior filters and increased energy use with the benefit of folks living longer.
I’m not sure I’m fully on board with turning my mates’ life expectancy into economic benefit but it is one way to do the maths. When you do this, many studies (all the ones examined in this article) showed a good benefit-to-cost ratio, ranging from 10 to 100 times return on the cost of the better filtration.
The takeaway? Specify mechanical ventilation with filtration that can remove PM2.5 particulate matter. This means MERV 13 or F7 filters or better. It is best if the equipment is designed to handle these filters from the start as it can mean larger filter boxes to reduce pressure drop and fan energy costs.
If you have a MVHR system please ask your supplier for a F7 or MERV 13 filter. F7 is to a ISO standard EN779:2012 and MERV 13 is to ASHRAE 52.2-2007; they are roughly equivalent to non-air-filtration-geeks. You can compare these here.
Image is from the article “Health Impacts of Indoor PM2.5 and Need for Particulate Matter Control in Occupied Spaces,” ASHRAE Journal June 2023, pg 32-34, by Hoy Bohanon, P.E., Leed-Ap, Member ASHRAE; Meghan Mcnulty, P.E., Member ASHRAE; Marwa Zataari, Ph.D., Associate Member ASHRAE.
Note there are 27 (!) references, so lots to dig into if you are interested.