Answer:
1. pedestrians
2. cyclists
3. motorists
4.vehicle passengers
5. horse riders
6. passengers of on-road public transport
(mainly buses and trams).
Natural environment has the ability to gather some pollutants yet if too much then the environment could no longer handle it. A leaky sewage can pollute an aquifer with I. arsenic as the contaminant. Arsenic is a metalloid existing in the Earth's crush. Exposure is natural yet can be aggravated by the human activities.
He works as a professional orator
