[Retric]

Your nose is really really bad chemical sensor because it caress more about novelty than absolute levels.

https://en.wikipedia.org/wiki/Olfactory_fatigue

Urban/suburban areas provide a different variety of smells which is easy to confuse with overall toxicity levels. Chemical sensors will sometimes line up with your expectations and other times be very different.

[schiffern]

Trust me, I know what vehicle exhaust smells like. ;)

Living outside the city, I'm not constantly fatigued to its odors. So that's not a factor.

But more to my original point, it disproves the "wind > location" idea (in my geography), since odor acts as a tracer for packets of air coming from the city.

I wish I could calm your anxiety, but on the bright side I am truly touched by your outpouring of concern for my respiratory well-being! Thank you, kind stranger.

[Retric]

You seem to misunderstand, Olfactory fatigue is very fast. When people fart for example the perception of smell goes away vastly sooner than the actual smell.

If you’re trying to judge air concentrations based on how intense the smell, it simply doesn’t work.

[schiffern]

I'm judging the presence of air pollutants. If I can smell it (ie above the lower detection limit), then I know I'm being exposed.

The converse is not necessarily true of course, but I can do this without hundreds of dollars in sensors. "Do what you can, where you are, with what you've got."

To account for sub-detectable pollution levels, I generally give myself a little extra buffer room. If I observe that detectable pollution odors begin at a certain point, I'll engage recirculate a half-mile before.

Generally nowadays I successfully avoid any detectable pollution/proxy odors, using the sort of preemptive planning I've described. You should try it!

---

TL;DR this whole thread: recirculate gives better air quality, just flush CO2 periodically, ideally when in relatively cleaner air

https://www.latimes.com/science/sciencenow/la-xpm-2013-sep-1...

https://news.ucr.edu/articles/2020/01/13/clearing-air-inside...

[Retric]

The converse is very much the problem.

Moving from constant levels of pollution to intermittent levels of population you notice ever stronger smells even as things improve. The reverse is also true, going from intermittent smells to constant toxicity it seems like things are improving.

This is the case because you most easily notice rapid changes not overall levels.

And again, both articles ignore the possibility of having better filters.

[schiffern]

> The converse is very much the problem.

Not really. What I currently do prevents any health flare-ups, so it's working for me.

I might be effected by sub-detectable levels of pollution. I definitely would be effected by detectable levels of pollution. So I know I'm better off, which makes me happy.

I do not confuse this with perfection, but this level of cost/benefit tradeoff is "good enough" for me. Some of these tricks might be helpful for other people too!

> Moving from constant levels of pollution to intermittent levels of [pollution]

This is not my situation.

> And again, both articles ignore the possibility of having better filters.

I didn't write the articles, I just cited them to support the fact that recirculate results in lower pollution levels in cars.

I, in my life, very much do not ignore air filters. :)

[Retric]

> recirculating results in lower <particulate> pollution < and higher non particulate pollution>

Again, assuming inadequate filters, better filters invalidate their results.

> sub detectable

This is very much detectable, we just ignore it. Come back from a long trip to a remote enough area and it’s shocking how much everything smells, even small country roads briefly stink of pollution.

But, I think the dead horse has been beaten enough at this point.