Yep, MERV13 or MERV14 is more than enough if all you're worried about is dust, pollen and smoke.

Because it's not as fine of a filter, far less air pressure is required to filter the air. This results in much, much quieter purifiers.

The endgame of this sort of goal is PC case fans. They've been optimized for decades now to squeeze every last bit of airflow for less and less noise, and they last for a couple decades or more.

Buying a multistage HEPA purifier is perfectly fine, but first one must get and use an independent air quality meter to measure air quality. This will help one understand which purifiers are helping and which aren't, also how much they're helping. It usually takes several purifiers, including at the source of air entry, to effectively lower the PM levels to very low numbers. Also, the filters must be replaced routinely.

Same on first visit, but loaded fine after reload.

The filter I have at my window turns black in a single month! I have to end up replacing it almost every month.

I strongly suggest getting an independent air quality meter that shows actual numbers. Speaking generally, the meters integrated in the purifiers are not trustable.

I'm personally betting, that they simply have easier access to more information, comparing to me at the same age.

When I started Uni, the "A diploma will guarantee you great job opportunities" mantra was unshakeable.

Now I think, the pendulum swung so hard in the other direction, that kids of same age have tons of refuttals at their disposal. It must take a lot more work, from parents, to instill and motivate what was once seen as a good career starter.

In developed nations we are past the peak of air pollution so kids are breathing cleaner air:

https://www.sustainabilitybynumbers.com/p/peak-pollution

look at any connections to the thyroid gland, down and upstream.

Poor breathing = less NO, less oxygen → potential stress on thyroid metabolism (and almost any other metabolism).

NO is nitric oxide: the paranasal sinuses are a major source of NO gas.

And NO gas has antimicrobial effects (helps sterilize inhaled air), acts as a vasodilator (helps regulate blood flow and oxygen delivery), and enhances oxygen uptake in the lungs.

It's still present in a lot of avgas! (Fuel for airplanes) Obviously much less impactful than being surrounded by lead-spewing cars, we haven't totally stopped lead-spewing generally yet.

It would be interesting to know how much leaded avgas specifically affects people. Clearly most of it is emitted high up in the atmosphere but there's still a lot of idling and taxiing around airports...

5th paragraph:

To make things even messier, heavy metals like lead and mercury can also be airborne and have been linked to harmful effects on the brain. For simplicity, we’ll talk about all of these under the same umbrella of air pollution, because they all contribute to negative health outcomes, including effects on the brain.

>it is guaranteed to get worse(long term average) everywhere on an continious ongoing basis

History shows otherwise.

What says you didn't? Smoking is associated with worse IQ development according to this study: https://www.sciencedirect.com/science/article/abs/pii/S00223...

not just brain is badly impacted by smoking, but everything else: skin, teeth, lungs, heart, vision, hormones, sleep, immunity, longevity, ..

Nope. Not necessarily.

a) fuck IQ. But since you are using it as a benchmark (here, at least). What is your IQ? How did you gain most of it?

b) How much are you smoking? Are you getting sub-level espresso effects from nicotine? (If you don't drink coffee, got anything to compare it with?)

c) How's your breathing? How often are you sick(ly)?

d) Where do you see yourself under the Bell curve? Professionally and or any other way you might believe is relevant.

Just think high frequency, max amplitude bell curves under bell curves. And then ... yeah, who says you didn't?