Carbon monoxide, often referred to by its scientific abbreviation CO, is an air pollutant. The main source of carbon monoxide emissions are automobiles and non-automobile equipment, but the burning of fossil fuels and industrial processing are also responsible. This pollutant has serious side effects, both for the body and the environment. Regarding the human body, carbon monoxide reduces the oxygen delivery and can cause problems with the heart and nervous system. From an environmental perspective, it creates smog which can effect both plant and animal life. The amount of carbon dioxide in our environment has been reduced by several endeavors, most notably the Clean Air Act and the transition to less harmful forms of energy.
Mercury is a naturally occurring element that has become harmful due to its overabundance. It is mainly released through the burning of fossil fuels and solid wastes. One method by which mercury has contaminated groundwater sources is through runoff from gold mines. The main method of exposure to excessive amount of mercury by humans is through consumption of fish and shellfish that have been contaminated. The effects of mercury on humans are dire. Serious harm can be done to the brain, heart, lungs and other vital organs. Pregnant women who ingest mercury can give birth to children with serious birth defects.
Lead can pollute both water and soil. Lead, along with copper, enters water primarily through plumbing systems. In 1991 the Environmental Protection Agency (EPA) passed legislation to establish standards for drinking water and curb the effects of lead. Lead infiltrates the soil through paint chips, factory pollution and leaded gasoline. In children, lead can cause learning disabilities and problems with holding attention. Leaded soil has been shown to cause violent behavior in children who play in it. In adults, lead can cause high blood pressure and kidney problems. These effects require long term exposure.