air
allowed
atmospheric
auto
ban
car
carbon
caution
dioxide
doe
economy
electrification
embargo
emission
engine
environment
exhaust
free
gas
icon
idle
idling
illustration
law
no
off
park
parking
pollution
poster
power
prohibition
reduction
road
rule
safety
sign
signal
start
stop
symbol
system
traffic
truck
turn
turn off
vehicle
warning
zone