Many are harmful effects, such as the pollution of air and water, while others are factors influenced by urban infrastructures such as highways and public transportation services.
Sewage and harmful emissions have led to the presence of contaminants such as mercury, lead, and flame retardants within the waters of Lake Ontario.
Improvements to air quality have been linked to the closure of coal-fired power plants and the reduced demand for electricity in the city.
[6] Over half of Toronto's air pollution is emitted within the city's boundaries with the largest local source being traffic including all types of on-road vehicles.
[7] Research carried out at the University of Toronto has shown noticeable air pollution hot spots near highways and major intersections that can have three to four times the city's average amount of ultrafine particles from by vehicle exhausts.
[5] Concentrations of volatile organic compounds (VOCs) and nitrogen oxides, two precursor components of smog, have been steadily decreasing in the city.
Under the city of Toronto's Environmental Reporting and Disclosure Bylaw of 2011, the use of tetrachloroethylene, also known as perchloroethylene or PERC, is now heavily tracked, requiring owners of dry-cleaning facilities to record detailed accounts of how it is used and recycled.
Sewage incinerators and other treatment plants across the city are often a large source of harmful pollutants such as nitrogen oxide, chromium, mercury, and carbon dioxide (CO2).
[17] The plant is one of Toronto's largest polluters, emitting over 38 tonnes of greenhouse gas emissions (GHG) every day as a result of its old incinerator.
[12] As part of the bylaw, the program ChemTRAC was created, which helps businesses identify major sources of chemicals in their facilities and analyses their releases.
ChemTRAC is now fully operational and is intended to reduce pollution from industrial and commercial sources by increasing public awareness.
[22] Toronto Water can remove some of these contaminants when the wastewater is treated at one of their treatment plants; however, many toxic chemicals remain and are often released into Lake Ontario.
[25] With a growing population and limited space at the landfill, the city' s current waste management system has been deemed unsustainable.
[26] Toronto currently does not have a long-term plan to move away from landfills, but is instead focusing on efforts to reduce overall garbage through waste diversion.
In February 2017, TEA convinced the City Council to investigate why waste diversion rates are lower in areas of privatized garbage collection.