| epa.gov | Environmental Protection Agency |
| uoguelph.ca | Canada's Aquatic Environments |
| upm.es | Environmental Software and Modelling Group, Technical University of Madrid |
| worldbank.org | World Bank - NIPR: New Ideas in Pollution Regulation |
| filthymess.com | When your surroundings are a filthy mess, someone is responsible |
| nsc.org | EHC Air Quality Program |
| giwa.net | GIWA - Global International Waters Assessment |
| casanz.org.au | CASANZ: Clean Air Society of Australia and New Zealand |
| ca.gov | California Air Resources Board |
| aircarecolorado.com | Denver Vehicle Emissions Testing Program |
| epa.gov | www.epa.gov/ |
United States , Virginia , Reston