Ideally in the summer clothes should be air dried outside, but if you use a dryer, the best time to use it in the summer would be just before the sun comes up, so that when the dryer pumps hot air outside, the cold air that gets drawn into the house with be the coolest air of the day.

Since dryers produce heat, in the winter why not run the dryer's vent duct through a HEPA filter of sufficient size, then into the crawl space, where the warm air will rise and heat the floor of the house? Or at least duct the heat back into the main part of the house, so cold outside air doesn't get drawn into the house.

In my original city, there is asbestos in the water ,,from the eroding concrete 9' channel.

If you have dyer exhaust to the indoors, bad for lungs.

Lint will also cause issues; moisture = black mold= un healthy.

But there is a trick: if you can, install a 4 foot p-trap, 4" insulated air duct...to allow fresh air, but the great part is that cold air only comes in when there is a negative house pressure, ie.when the dryer is  running/ gas furnace etc, .When your dryer is running, it will draw air from this p -trap, presumably in the basement.

So in winter time, your house stays warmer... no drafts.

Sunshine is the best= sanitizes clothes. FREE.

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https://www.houserepairtalk.com/threads/fresh-air-intake-draft.13227/

...The only cold source i found is the fresh air intake. It is currently a 4" insulated pipe that goes down to the floor then back up 3' like a p trap. .
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Ideally in the summer clothes should be air dried outside, but if you use a dryer, the best time to use it in the summer would be just before the sun comes up, so that when the dryer pumps hot air outside, the cold air that gets drawn into the house with be the coolest air of the day.

Since dryers produce heat, in the winter why not run the dryer's vent duct through a HEPA filter of sufficient size, then into the crawl space, where the warm air will rise and heat the floor of the house? Or at least duct the heat back into the main part of the house, so cold outside air doesn't get drawn into the house.

If your dryer runs on gas, you'd be turning your house into a makeshift gas chamber by doing this.

Yes.

I'm not sure if gas heated dryers have a separate exhaust for the gas.

Humidity in the crawl space is a good concern, but in the house during winter when the air is dry shouldn't cause harm for the relatively short amount of time used.