Will the PM 2.5 masks become useful at avoiding the cams being installed in tier 1 cities for personal identification when e.g. crossing with a red light and being automatically fined in our wechat/alipay accounts?

It depends if you intend to offend or not, but I think the eyes are more of a factor.
Shaved heads seem to confuse some apps.

The position of the nose, mouth and chin should be very important, more so than the eyes, as we are not talking about iris scanners. And hair and beard should not be taken into account, as this changes too frequently.
But of course the cams will become better with time at profiling people from their behaviour (the way we move), vehicle, etc.

Maybe if combined with really dark sunglasses? But have we come to this now?
Bumper sticker noticed by Jim Goodman: "Make 1984 fiction again!"

I am not talking iris scanning here. Bone structure around the eyes and eye shape are the metrics I was considering.

OK, well - BIGass sunglasses then, maybe full-face tinted motorcycle helmet face shields.
"Fight the Future!" - X-Files, Season 6 or so, about 1998. Guess we didn't.

It's interesting how public policy here is at odds with itself. Official permissiveness towards air pollution leads to widespread use of face masks, which in turn undermines the use of facial recognition technology for social control.

You can also buy latex mask that look like a real person's face if you want to fool the cameras.

"Your mission, should you choose to accept it..."

And in honor of my 100th post, I am upvoting everyone else's posts on this thread. Whoo hoo.