The Tennessee Air Pollution Control Board is suggesting the state lower the maximum speed for tractor-trailers to 55 mph from the current 70 mph.

The effort is seen as a way to meet federal air quality requirements, according to the Associated Press.
In some counties, the state estimates that cars and trucks produce more than half of the emissions that help form ozone.
The air pollution board also suggests banning truck drivers from idling engines for long periods and requiring companies with government contracts to use clean engine technology and fuel additives for heavy duty equipment.
The board is trying to push Tennessee counties into compliance with new federal air quality rules that take effect in two years.
State Rep. Phillip Pinion, D-Union City, said the state is a major artery for truckers, and lower speed limits would affect the income of drivers and delay deliveries.