英文關鍵字
air
atmosphere
background
boy
building
catastrophe
chemical
chimneys
china
choke
city
contamination
cough
damage
danger
dangerous
dirty
ecology
environment
environmental
epidemic
equipment
factory
filter
gas
gasp
guy
health
human
industrial
industry
kid
male
man
mask
one
outdoors
person
pipes
poisonous
pollution
protect
protection
protective
respirator
safety
smoke
smokestack
urban
warming