ACID RAIN

music
Ambience: traffic whistles

The distinctive sound of a traffic policeman’s whistle, on a busy street in Mexico City. The smog here is among the worst in the world, and scientists have found that it’s not only bad for people, but for buildings and monuments, too. I’m Jim Metzner and this is the Pulse of the Planet.

“In Mexico City the density of vehicular traffic is very large. (and) This means that there is a tremendous amount of air pollutants generated by the burning of the gasoline.”

Dr. Seymour Lewin is a Chemistry professor at NYU, who has studied the effects of acid rain on ancient and modern structures.

“The rate of deterioration of exposed stone over the past century has been greater than the amount of deterioration over the preceding 2,000 years, and that’s because of the increasing concentration of acid in the atmosphere in the most recent century.”

“The way in which acid rain attacks exposed stone consists of two quite independent processes. The first process is direct erosion – the acid in the acid rain simply dissolves away some of the surface stone. Instead of having sharp lines, fine detail, it all gets smoothed out sort of like a candle melting as the result of heat.

“If good daily maintenance is applied – this means once a month or maybe once every six months, cleaning of the facade – then the attack of acid rain is not stopped, but the amount of decay, the outer deterioration, is relatively small.”

Pulse of the Planet is presented by DuPont, makers of better things for better living.

music

ACID RAIN

Monuments that have stood for thousands of years now face a new environmental threat.
Air Date:10/23/1991
Scientist:
Transcript:

music
Ambience: traffic whistles

The distinctive sound of a traffic policeman’s whistle, on a busy street in Mexico City. The smog here is among the worst in the world, and scientists have found that it’s not only bad for people, but for buildings and monuments, too. I’m Jim Metzner and this is the Pulse of the Planet.

“In Mexico City the density of vehicular traffic is very large. (and) This means that there is a tremendous amount of air pollutants generated by the burning of the gasoline.”

Dr. Seymour Lewin is a Chemistry professor at NYU, who has studied the effects of acid rain on ancient and modern structures.

“The rate of deterioration of exposed stone over the past century has been greater than the amount of deterioration over the preceding 2,000 years, and that’s because of the increasing concentration of acid in the atmosphere in the most recent century.”

“The way in which acid rain attacks exposed stone consists of two quite independent processes. The first process is direct erosion - the acid in the acid rain simply dissolves away some of the surface stone. Instead of having sharp lines, fine detail, it all gets smoothed out sort of like a candle melting as the result of heat.

“If good daily maintenance is applied - this means once a month or maybe once every six months, cleaning of the facade - then the attack of acid rain is not stopped, but the amount of decay, the outer deterioration, is relatively small.”

Pulse of the Planet is presented by DuPont, makers of better things for better living.

music