A、Scientists have managed to persuade industries to take measures to reduce emissions of gases into the atmosphere. B、There is n

W: Dr. Cottam. You’re studying the effects of air pollution on trees?
M" That’s right.
W: Could you tell us something about it?
M: Trees in industrial areas grow much more slowly than they should. Worse still, trees hundreds of miles away also seem to be damaged by these same industries.
W: You mean "acid rain", I suppose.
M: Yes.
W: What effects does acid rain have on the environment’?
M: For a start, lakes polluted by it in this way can no longer support any fish. Gradually the acid rain washes elements out of the soil essential for healthy plant growth.
W: But I think that there’s no general agreement on the causes and effects of acid rain.
M: That’s right. The distances involved are so great that it’s impossible to prove what’s actually going on. And no one will willingly accept even partial responsibility for something that happens miles away.
W: But trees are dying. No one can deny that.
M: Exactly.
W: So how does your investigation go?
M: We’ve set up special glasshouses to keep a careful observation on the growth of the plants. We pump in controlled amounts of air pollutants, including ozone, which isn’t always associated with acid rain.
W: Which industries emit ozone?
M: Mainly oil refining industry. We also occasionally cool the atmosphere in the greenhouses, which causes frost.
W: Have you had any results from these experiments yet?
M: It’s still too early to draw any definite conclusions. But we’ve noticed that plants at low temperatures are affected more severely than those at normal temperatures.
W: So cold weather makes the effects of pollution worse?
M: It certainly looks that way. But we still hope to be able to persuade industries to take measures to reduce emissions of gases into the atmosphere.