The appalachian mountains formed as a result of

Converging plate boundaries. continent to continent plate boundary converging if you want to be more specific.
to converge means to bring something together, that's how I always remembered. Transform boundaries move side to side, and are the reason for mainly fault lines, such as the San Andreas Fault in California. All plate boundaries do occur at subduction zones.

Air pollution: “combustion results in gases such as nitrogen oxides, nitrogen dioxide and particulates. the main causes of air pollution include transport, domestic combustion and industrial processes. pollutants from these sources can cause problems in the immediate vicinity and a distance away.”

Do you have a picture for this problem?