Natural Resource Damage Assessment (NRDA)

Nelson, Gaylord U.S. Senator (D-Wisconsin) and Founder of Earth Day (1916–)

New Left

NOx (Nitrogen Oxides)

Noise Control Act of 1972

Noise Pollution

Nonaqueous Phase Liquids (NAPLS)

Nongovernmental Organizations (NGOs)

Nonpoint Source Pollution

Nuclear Regulatory Commission (NRC)

Occupational Safety and Health Administration (OSHA)

Ocean Dumping

Ocean Dumping Ban Act

Oxygen Demand, Biochemical

Ozone

Particulates

PCBs (Polychlorinated Biphenyls)

Persistent Bioaccumulative and Toxic (PBT) Chemicals

Persistent Organic Pollutants (POPs)

Pesticides

Petroleum

Phosphates