What ever happened to "Acid Rain?" Why don't we hear about acid rain anymore?

New rules and regulations were put in place to curb and reduce levels of pollutants. For example, living in the northeast, all a person had to do was was to go to s cemetary. .Headstones that were in place for hundreds of years literally began disolving with 20 years, so much so that it has become nearly impossible to read the names and date etched into them identifying the people buried. This is a fact. I recall going with my parents to the cemetary on memorial day to lay flowers and reading the headstones. Returning as an adult, some of the older stones and monuments from the 16,17, and 18th which were readable once, are almost wiped clean.