Greenhouse Gases (GHG's) are mostly carbon dioxide (CO₂), and some methane (CH₄). The biggest source of greenhouse gases is the burning of fossil fuels like coal and oil in order to generate electricity and power factories. Back to ratings.

Common Air Pollutants are nitrogen oxides (NO_x), volatile organic compounds (VOCs), sulfur dioxide (SO₂) and particulate matter below 2.5 microns in size (PM-2.5). These pollutants contribute to acid rain, smog formation, and aggravate respiratory illnesses like asthma. Back to ratings.

Toxic Air Pollutants include all 188 of the hazardous air pollutants identified by the U.S. Congress in the 1990 Clean Air Act amendments. Back to ratings.

Common Water Pollutants include nutrients, suspended solids, sediments and biological oxygen demand. These types of pollutants disrupt freshwater and saltwater ecosystems. Back to ratings.

Toxic Water Pollutants include chemicals, such as pesticides, that are toxic to humans and can make drinking water unsafe or can be taken up by fish or food crops that rely on the polluted water to grow. Back to ratings.

Water Use refers to the consumption of water for irrigation of agricultural crops, or for cooling or otherwise supporting industrial processes. Back to ratings.

Land Use refers to the loss of biodiversity caused by replacing natural ecosystems with industrial ecosystems. In order to calculate these land use impacts, the Union of Concerned Scientists determined that urbanizing one acre of land is approximately equally damaging as grazing livestock on 17 acres, producing forest products on 10 acres, growing crops on 6 acres, or building highways on 0.6 acres. Back to ratings.