Thermal Pollution
Thermal pollution is going to be a factor of increased importance due to climate change as it encompasses everything from region down to the density of buildings and even further to the materiality of the environment.
These range of factors are captured within the concept of the Urban Heat Island, a metropolitan area (source). Heat stress is associated with elevated heart rates which can lead to heat stroke, cardiovascular issues, and a loss of sodium and potassium which is all of particular risk for those with weakened hearts, often the elderly (source).
Urban heat islands generally have reduced air and water quality due to the industrialisation, transport, and density, so it is normal for heat pollution to rise with air pollution.
The following excerpt from Teqoya articulates additional problems relating heat to air pollution:
“Sunlight and high temperature trigger chemical reactions between primary air pollutants such as nitrogen oxides (emitted by engines) and oxygen, causing a chemical reaction that forms ozone. The hotter the day and the more intense the sun, the more ozone is formed. Ozone is a very active oxidant, which exacerbates lung diseases such as asthma and can cause breathing difficulties even in healthy individuals. Heat and sun also transform primary particles into secondary, smaller particles that can be more toxic. These secondary particles, which are photochemically produced by sunlight, are of crucial importance: they are ubiquitous and can make up to 90 percent (in number) of the total particulate matter. Secondary particles are smaller than one thousandth of a millimeter (very fine particles) and even smaller (ultra fine particles). They can enter deep into the lung airways when inhaled, and even penetrate the blood. A team of researchers at the University of Bern (Switzerland) has recently shown that secondary particles from gasoline combustion in engines directly damage lung tissue as well as weaken its defence system as a result of their physical and chemical properties - lung tissue can be damaged, and pathogens (viruses, bacteria) can enter the lungs easier. Asthmatics people are particularly at risk.”
How thermal pollution is an urban planning problem
The core problem of heat in cities is identified through the Urban Heat Island (UHI) effect; where a metropolitan area is a lot warmer than the rural areas surrounding it due to human activities. The main cause of the UHI effect is from the modification of land surfaces. Waste heat generated by energy usage is a secondary contributor. The UHI decreases air quality by increasing the production of pollutants such as ozone, and decreases water quality as warmer waters flow into area streams and put stress on their ecosystems.
Sun and rain transform asphalt binder into potentially toxic compounds. Concrete and black asphalt in particular are two problematic materials as they retain heat. Dark-coloured asphalt positively bakes when temperatures rise, absorbing 80% to 95% of the sun’s rays. On a sweltering summer day when the mercury reaches 100 degrees Fahrenheit, the surface temperature of L.A.’s roads can climb to as much as 50 degrees higher. The U.S. city of Los Angeles has sought to paint roads white as a way to repel heat. Recommended further reading is ‘Dangerous Heat, Unequal Consequences’