alert
alerting
alertness
avalanche
biohazard
biological
caustic
caution
cctv
crossbones
danger
dangerous
death
disabled
electricity
emblem
environment
error
explosive
flammable
gas
hazard
high
hot
icon
label
message
no
nuclear
poison
protection
radiation
risk
round
safety
set
sign
signal
skull
stop
substance
symbol
toxic
truck
w16
warning
waste
weapon