A: I can't believe how polluted the air is. I can hardly breathe.
B: Yes. Pollution is hanging like a brown cloud over the city today.
A: The air would be cleaner if people stopped driving and started taking buses.
B: Well, that would help. But I don't think cars are the only problems.
A: What else do you think causes pollution?
B: Well, the factories pollute the air a lot, too. Dirt and smoke are pouring from factories and spoiling the air.
A: Yes, that's quite true. But we can't close down the factories, and people can drive less.
B: Sure, but how are you getting people to do that?
A: Well, I'd improve the bus service and charge less
B: That's a good idea.