A new study shows how diesel exhaust can be harmful to your health.
This type of exhaust is mainly generated by buses, trucks, trains and ferries.
Experts say particles from diesel exhaust can remain airborne and travel long distances before being inhaled.
The latest research on the subject is from the West Virginia University School of Medicine, where researchers studied the effects of diesel exhaust on rats.
They found a chemical component of the exhaust can hinder the ability of some arteries to regulate blood flow to bone marrow.
The effect could be most pronounced among men, post menopausal women and the elderly.