WAEC - Biology (2014 - No. 27)

Pesticides that are sprayed on to fields and used to fumigate soil can give off chemicals called volatile organic compounds, which can react with other chemicals and form a pollutant called ground level ozone. 

Crude oil extraction, transportation, refinement, and burning release greenhouse gases like carbon dioxide and methane, contributing to climate change and air pollution, with harmful effects on human health and the environment.