Would a moist cloth wrapped around the nose be reasonably effective as compared to an anti-pollution mask?
that leaves the danger of the particulate matter which in my opinion, could be prevented with just a cloth wrapped around the nose and mouth.


Diesel particulates are mostly in the 3-30 nanometre range of sizes. This is very fine and will not be stopped by normal cloth.

3M say a P2 (EU rating) filter should reduce exposure to diesel particulates. A P3 mask should remove a higher proportion of particles. I suspect these filters might not remove the finer diesel particulates.

Most of these masks are not intended to supply a large volume of air, they are workplace masks not sports masks.

Some cycling mask makers write about PM10 filtering. Note that PM10 are coarse dust particles 2500 to 10000 nanometers in size. That's a lot larger than most diesel particulates.

The key to an effective filter is a good air-tight closure against the skin around the entire perimeter of the filter. You cannot obtain the necessary fit using cloth alone.

If anecdotal stories have anything to teach it is that you should expect a white filter to become blackened even on short rides and that you therefore need to replace the filter every ride.