Regulations on semi truck exhaust?

Question

Why is it that we have so many regulations on car exhaust but semi trucks drive around blowing out thick black smoke? Seems like that smoke would be just as bad.

Answer 1

Truck exhaust IS being tightly regulated, and it is costing the public as much as the regulations for cars.
Several years ago, EPA mandated certain CLEAN fuel be required. and we implemented that fuel. Then the EPA required that ALL trucks be subject to a bi-annual exhaust test (Infra-red/laser instrumentation), and we are doing that.
The NEW fuel required is another CLEAN fuel, with less sulfur. That regulation just became effective this month. More expense for the public. The trucks are what moves product to market(s), and the trucking industry cannot absorb the cost. They pass it along to the contractors, who pass it on to the consumers.
There is a difference though between what you can SEE and what you can't.
Most pollutants from either diesel or gas are not visible. They are hydrocarbons (unburned fuel), carbon monoxide (partially burned fuel), and oxides of nitrogen (the result of very high temperatures in the cylinders and pressure, compression).
What yo SEE from a big-rig or a bus is called particulate, or soot. Though it is a pollutant for the environment, it doesn't remain in the air all that long, because when it cools, it settles to the earth floor.
There IS MUCH more regulation coming down the pipe, but it has to be implemented slowly, or no one could afford it, especially the consumer.

Answer 2

HERE HERE to IRONHAND-(lifting my coffee cup)
someone who's got an answer, Ive been an auto tech for a long time, been repairing the big stuff now for about a year, and glad to see someone who knows what there answering, good job