affair
air
auto
automobile
blowing
car
city
climate
combustion
danger
diesel
dioxide
dirty
eco
effect
emission
energy
engine
environment
environmental
exhaust
fog
fraud
fuel
fume
gas
gasoline
hazardous
health
industry
money
monoxide
pipe
pollution
power
protection
rust
smoke
soot
steam
structure
technology
toxic
traffic
transportation
vehicle
waste