The city of Los Angeles is trying a new tactic to address rising temperatures, painting streets with a grey paint specially designed to reflect heat. Called CoolSeal, the paint was originally created to help reduce the heat from airstrips, helping to hide them from spy satellites.
The city tested the paint on a parking lot located in one of the hottest parts of the city, and found that it significantly reduces ground level temperatures.
“We found that on average the area covered in CoolSeal is 10 degrees [F (5 degrees C)] cooler than black asphalt on the same parking lot,” said Greg Spotts, a city official, speaking to Peter Holley at The Washington Post. “We thought it was really interesting. It’s almost like treated asphalt warms at a lower rate.”
According to city officials, the coating costs roughly 40,000 dollars per mile and lasts seven years.
The plan to use CoolSeal aims to combat what’s called the urban heat island effect, in which densely developed urban areas see higher temperatures as a result of concrete, buildings, and asphalt replacing the vegetation that would otherwise provide cooling shade from the sun. When a city’s population rises above one million people, the urban heat island effect can lead to temperatures 22 degrees Fahrenheit, or 12 degrees Celsius, higher than those in adjacent areas.
Not only does this lead to increased risk of heat exhaustion, or worse for vulnerable populations, it also results in higher use of air conditioning and energy consumption.
City officials say the use of CoolSeal could also help residents who work outside, and reduce ground temperatures for pets. Since the paint is extra reflective, less energy is consumed to light roads and parking lots treated with the paint.
The city plans to monitor the areas already treated with CoolSeal through autumn, before considering a wider application in the future.
Recently, scientists have looked into other ways to reduce temperatures in cities, such as increasing foliage and even covering buildings with plant life – which also helps to absorb carbon dioxide emissions.
Los Angeles is the first US city to put such plans into action, as part of a broader plan to reduce temperatures by about 3 degrees Fahrenheit, or 1.2 Celsius, over the next 2 decades.
“We think that more than 10 percent of the city is asphalt – that’s 69,000 city blocks,” Spotts added. “There’s been estimates that suggest covering a third of the city’s pavement with a cooler materials might be able to move the needle on the city’s temperature.”
“We’re not ready to do that, but we do want to explore what it might take to go big and take this thing to scale.”