英文關鍵字
air
asia
background
boy
catastrophe
caucasian
chemical
chimneys
choke
city
concept
cough
damage
danger
dangerous
dirty
ecology
environment
environmental
epidemic
face
factory
filter
flu
gas
gasp
guy
health
human
industrial
industry
kid
male
man
mask
mouth
outdoors
person
pipes
plant
poisonous
pollutant
pollution
protection
respirator
smoke
stack
standing
wear
young