LOS ANGELES • Can a splash of grey pavement paint help combat global warming?
In Los Angeles, where summer temperatures regularly surpass 38 deg C, workers are coating streets in special grey treatments in a bid to do just that.
Normal black asphalt absorbs 80 to 95 per cent of sunlight, while the grey "cool pavement" reflects it - dramatically lowering ground temperature and reducing urban street heat, say advocates of the method.
During a demonstration of the technique, Mr Jeff Luzar - sales director at GuardTop, which markets the product - showed how applying the paint could drop street temperatures by about 11 deg C after just one coat.
The City of Angels, home to four million people, is the first major city to test the technology on a public road, after initial trials on carparks.
"We are hoping to inspire other cities to experiment with different ways to reduce the heat island effect," said Mr Greg Spotts, assistant director of the city's Bureau of Street Services.
"Potentially there could be a huge market for cool pavement products, and in fact, it's part of a much larger economic trend where solutions for climate change could be the next great investments for the future," he added.
The city will also monitor how residents react to the newfangled asphalt - and how quickly the notoriously heavy LA traffic dirties the grey coating.
Normal black asphalt absorbs 80 to 95 per cent of sunlight, while the grey "cool pavement" reflects it - dramatically lowering ground temperature and reducing urban street heat.
Civil and environmental engineering assistant professor George Ban-Weiss, of the University of Southern California, said cool pavements show promise in reducing heat, but "may have some environmental penalties".
"Recent and current research is working out whether the environmental benefits of cool pavements outweigh those penalties," he said.
Still, "the city of Los Angeles is taking the right approach and installing and assessing several cool pavement test sections before committing to widespread adoption".
Prof Ban-Weiss added that heat mitigation strategies like planting trees along streets and using cool roofing materials were more "no-brainer" remedies.
Environmental science professor Alan Barreca, of the University of California, Los Angeles, said the pavement cooling technology could be more equitable than current methods like air-conditioning.
"Not everyone has the resources to use air-conditioning, so there's concern that some low-income families will suffer," he said.
"It can protect people who have to be outdoors," he said of the grey paint.