They may not belch black smoke, but the organic solvents and oily smoke that they do release are a form of pollution, and perhaps even carcinogenic.
像住家附近的乾洗店、餐廳、飯店，雖然沒有冒黑煙的煙囪，但它們排放的有機溶劑、油煙等都是汙染物，甚至是可能的致癌物。