white

blue

sky

nature

environment

plant

air

energy

warm

danger

steel

industrial

power

technology

stack

grunge

winter

smoke

smog

fog

industry

tower

ecology

toxic

global

clean

dirty

economy

Pollution

fume

chemistry

station

pipe

cleaning

factory

climate

coal

steam

dust

chimney

emission

exhaust

Greenhouse

fumes

steaming

shaft

pollute

echnology

chemically