I’d be curious to know how much of the airborne fine particulate matter is from combustion of #6 and #4, and how much is from tire particles. You would be amazed how much is in the air in a big city. We were involved in doing some indoor air quality studies some years ago (mid-90s), and couldn’t figure out why one of the tenant’s floors had all sorts of particulates in the outdoor air being introduced into the space, and the others didn’t. It turned out that the upper floors were getting their outside air from the roof, and the lowest floor was getting its outside air from grates down at grade.
I wonder if the people coming up with these rules have looked at such things, or if they’re just environmental extremists with “ban it all, as soon as we can get away with it” attitudes.
Purely co-incidentally, the hospital I work at was VERY recently undergoing asbestos remediation in one of the buildings on campus, and (surprise-surprise) several of the nursing staff working INSIDE that particular building got all bent out-of-shape over asbestos exposure (since that was the concern of the moment)...
Of ALL sampling stations on, in, and around the building in question, including the floor, ward, and very STATION of the concerned employee (you have no idea how much I loathe most RN’s),
The station with the MOST asbestos was THE ONE 2 FEET FROM THE STREET!