Here’s a hack that’s been around since the very start of the hot rod movement. Car exhaust flame throwers work by interrupting the spark to the engine. This dumps raw fuel into the exhaust system.

It is critical because, unlike other issues, exhaust smoke is linked directly to the car's engine. The respiratory system is the closest thing in biology to which you can compare the exhaust.

A major, but unregulated source is car brake wear, which exhaust emission reduction measures have not diminished," the team explained in their study. The scientists looked at the effects of ...