Diesel fumes suppress immune response

Recurring exposure to soot particles from diesel exhaust reduces the immune system’s capacity to fend off infection more persistently than does a one-time exposure to an equivalent amount of particles, tests on rodents indicate.

Inhaling particles less than 2.5 micrometers across is harmful to the heart and lungs. A past study showed that breathing air filled with such emissions for 4 hours temporarily suppressed rats’ immune defenses against the bacterium Listeria monocytogenes.