Cause - In the Black Triangle of Germany, Poland, and the Czech Republic, many factories burn lignite as their main fuel. Soot from this coal blackens the air and gives off sulfur dioxide and nitrogen oxide.

Effect: These chemicals react with water and they form acids which fall on lakes and kill fish. Acid rain can also harm forests. It weakens trees by eating away at their leaves or needles. It can corrode building materials like limestone, sandstone and marble.

Acid rain