Pacoima is baking under the California sun.<\/p>\n
To fight the heat, Los Angeles coated its black asphalt with a special blue-tinted material.<\/p>\n
This simple science reflects sunlight back into space. Surface temperatures plummeted by nearly 22\u00b0F.<\/p>\n
It is a bold shield against the urban heat island effect. Residents now walk on cooler streets that protect the community\u2019s health.<\/p>\n
But what happened after Los Angeles painted its roads blue?<\/p>\n
Reflecting the sun: How blue streets break the heat cycle<\/p>\n
Los Angeles has spent decades fighting extreme heat.<\/p>\n
The now-infamous dark asphalt makes this issue worse.<\/p>\n
Standard roads absorb up to 95% of solar radiation, turning streets into thermal batteries.<\/p>\n
Once night emerges, this stored energy is released back into the atmosphere, creating a \u201cheat island\u201d that keeps neighborhoods dangerously warm.<\/p>\n
That is where the oddly blue roads came in\u2014a small clue to a cooler future.<\/p>\n
In Pacoima, the GAF Cool Community Project coated 700,000 square feet of pavement with StreetBond, a water-based epoxy.<\/p>\n
While some coatings look gray, many appear blue to maximize solar reflectance without creating a blinding glare for drivers. This simple science reflects sunlight into space, slashing surface temperatures.<\/p>\n
This technology protects vulnerable residents from heat-related illness.<\/p>\n
But what happened after Los Angeles painted its roads blue?<\/p>\n
What scientists found when the sun hit these new blue roads<\/p>\n
A study was undertaken to focus on urban heat and cool pavement technology.<\/p>\n
Researchers aimed to measure how blue roads responded to sunlight.<\/p>\n
Including surface temperatures, reflected heat and energy, as well as thermal effects nearby.<\/p>\n
Urban environments can create heat traps and bubbles.<\/a>\u00a0<\/p>\n The difference in temperatures on these blue roads was not imaginary. The streets behaved far differently.<\/p>\n However, cooler roads do not always result in cooler drivers.<\/p>\n They did help reduce the heat trapped by the roads. Which could ease nighttime heat for drivers, too.<\/p>\n In other parts of the world, roads are painted red.<\/a> This was supposed to make driving safer.<\/p>\n But even those red roads created new heat islands.<\/p>\n But where did the heat go?<\/p>\n Cooling a specific surface can\u2019t erase heat completely.<\/p>\n Researchers weren\u2019t just studying the blue roads.<\/p>\n They studied what happened after the road turned blue.<\/p>\n Their findings have been detailed in the study, \u201cMicrometeorological effects and thermal-environmental benefits of cool pavements: findings from a detailed observational field study in Pacoima, California,\u201d published in Environmental Research Communications.<\/a><\/p>\n A 22-degree difference: The science behind LA\u2019s famous blue pavements<\/p>\n The now-famous blue roads were part of a city-wide cool pavement strategy.<\/p>\n LA applied these blue reflective coatings to some roads. The aim was to fight the urban heating island effect.<\/p>\n The color change was a clue about the new impact on the roads. The coating (StreetBond\/DuraShield-SR) works by reflecting Near-Infrared (NIR) radiation.<\/p>\n Drivers noticed that stretches of road were far cooler than others. Surface temperatures plummeted by as much as 22\u00b0F (12.2\u00b0C).<\/p>\n But only those with the new blue coating.<\/p>\n The effect of these blue roads was almost immediate. In the afternoons, roads felt like an open oven ready for baking.<\/p>\n Meaning that more heat was escaping in the late afternoon. Making the night far cooler for drivers.<\/p>\n Less heat was trapped by the road surface. Leading to a much cooler driving experience.\u00a0<\/p>\n The Physiological Equivalent Temperature (PET)\u2014how humans actually feel the heat\u2014dropped.<\/p>\n Data points to the fact that hot nights are often deadlier than hot days.<\/p>\n California regularly faces extreme heat.\u00a0<\/p>\n Which has led to exceptionally high temperatures, even when temperatures should be far cooler.<\/a><\/p>\n It\u2019s all in the name of saving lives<\/p>\n Thankfully, city officials have turned to blue roads to address city-wide heat island issues.\u00a0Reducing heat released during the evening can actually save lives.<\/p>\n