Question

Why has the relative importance of the Pittsburgh steel industry declined?
what are petrochemicals used for?

Answer 1

The relative importance of the steel industry in Pittsburgh declined because it imploded owing to high production levels that were not able to match up with similar demands. Consequently, it resulted in charge scale layoffs. The steel industry in Pittsburgh was also responsible for the large scale pollution in the city, making it one of the most polluted cities of the USA.
During the 1970s and 1980s, the city was faced in the layoffs and closure of the steel mills and was undergoing Urban Renewal with Renaissance II, that facilitated the growth of the services industries to check in the pollution levels, of the city resulting from the steel mills.

Petrochemicals are used for making synthetic rubber, latex paints, anti freeze in cars, solvents, and cellophane amongst several other products.