One factor is in this subject of black lung is diesel exhaust. When you see a truck spewing black smoke into the air you are looking at oily carbon particles from the incomplete combustion of the fuel.

The contingency fee lawyers are starting to get into this because of the health problems of people who work on diesel powdered trucks. Normally black lung disease is associated with coal miners. But now they are seeing something similar in those who work around diesel powdered vehicles.

The black soot produced by these engines is less than a micron in size. Carried for fairly long distances with wind.

They used to make a black carbon pigment via the incomplete combustion of various types of oil. Known as oil black and saw extensive use in tire production and in various plastics. More recently these oil blacks came under suspicion as being carcinogenic.

While poorly maintained gasoline fueled motors will spit out carbon particles the largest source are diesel engines. In countries where small combustion engines are run on mixtures of gasoline and lubricating oil these engines produce a good bit of oily carbon particles.

While gasoline powdered vehicles have been required to use pollution control devices the trucking industry has escaped most attempts to clean up their exhaust emissions.