Breathing in nitrogen oxide and sulphur oxide often leads to respiratory problems, and particulate matter has been linked to diseases such as asthma, bronchitis, emphysema and various forms of heart disease.  Volatile organic compounds can cause even more serious problems, from cancer to brain damage.

The presence of toxic chemicals or heavy metals in lakes and rivers affects drinking water, as well as the health of animals and fish that drink from the water, or live in it.  When human beings eat the animals or fish they are also eating the chemicals consumed by the animal.  There have been reports of mutations in animals and fish in ecosystems downstream from tar sands projects, and people who live in the area are very concerned that increased health problems may be linked to contaminated food and water sources.