Risk factors:
(1) accumulation of fumes to a high concentration
(1a) poor ventilation
(1b) weather inversion
(2) duration of exposure
(2a) short term for acute intoxication
(2b) long term for chronic toxicity
(3) large number of engines
(4) engine malfunction
(5) crude fuels that combust poorly or that contain contaminants
Factors making a person more susceptible:
(1) cardiopulmonary disease including COPD and asthma
(2) ability to protect self (leave if affected, use personal protective device, etc)
Ways to reduce risk:
(1) improve ventilation
(2) make sure engines are functioning properly
(3) use higher quality fuels
(4) turn off engine when not in use