4 ms·
Yes - there are other poisons as well hidden behind those particles, but it's very hard to measure the composition of those particles in real time. Particulate
by jvanderbot 2y ago
Yes - there are other poisons as well hidden behind those particles, but it's very hard to measure the composition of those particles in real time. Particulate matter can be measured with a $20 sensor from Sparkfun, so it's an often-used proxy.
As for why the particles sizes are differentiated, I think it's because some sizes can cross barriers into the blood - and are therefore concerning regardless of the contents. pm 2.5 can reach the deepest parts of the lungs and just muck up that whole area regardless and cause all kinds of systemic inflammation. pm 10.0 generally doesn't reach that deep but still causes eye/ nose/ throat problems IIRC.
If there is near-zero or undetectable particulate matter, then that would preclude lead particles as well, obviously.
- culi 2y agoThis seems like a reasonable explanation, thanks
- hatmatrix 2y agoIt's widely thought but not conclusively found that there are certain constituents that are more toxic than others. As you say, the problem lies in the ability to measure these constituents more widely. However, there is a hypothesis [1] that maybe there is something about the collective mass as negative association with health effects have been found all over the world where the composition changes drastically. A more recent hypothesis [e.g., 2] is that many health problems from particles stem from persistent reactive oxygen species that cause oxidative stress, and these reactive species form from many different mechanisms so likely scales with the collective mass, which has been serving as a surrogate metric. [1] https://doi.org/10.1016/S0048-9697(99)00513-6 https://doi.org/10.1016/S0048-9697(99)00513-6 [2] https://doi.org/10.1038/srep32916 https://doi.org/10.1038/srep32916