Factories and plants are some of the main contributors to the air pollution. Emissions are regulated by the United States Protection Agency ("USEPA"). The Agency places special concern on the following emissions: sulphur dioxide (SO2), hydrogen chloride (HCL), carbon monoxide (CO), nitric oxides (NOx), particulates (PM), volatile organic compounds (VOCs) and hazardous air pollutants (HAPs), including chlorinated hydrocarbons (dioxins) and heterocyclic organic compounds (furans).