Workers apply cool pavement in a parking lot in a Phoenix park. The pavement is a lighter color than traditional asphalt. (Photo: City of Phoenix)
Wildfires ravaging the west. Heat waves gripping the globe. Unprecedented floods killing dozens. Such are the weather-related events of just the last few weeks.
The world is coming to grips with the enormity of mitigating the effects of climate change. Aside from turning up the air conditioner, a number of cities are taking action by embracing so-called passive cooling techniques (those that don’t require electricity) such as using light, reflective colors that can leave surfaces and the surrounding area cooler.
In Denver, local governments acquiesced to resident demands and mandated white roofs. In Los Angeles and Phoenix, roads are getting a coat of white paint.
“Paved surfaces such as roads, parking lots, and sidewalks, account for up to 40% of the surface area in an average city and absorb a lot of solar energy that heats our communities,” says the website for Global Cool Cities, a non-profit with partnerships in two dozen cities, including some of the hottest.
An EPA publication on heat islands cites research suggesting air temperature could be reduced by 1°F by increasing albedo (the level of reflectance in pavement) throughout a city from 10% to 35%, which would result in lower energy use and reduced ozone.
But in Clark County, where the temperature is increasing faster than any other city in the country, officials are focused not on the blazing heat emanating from valley roads, but on dust.
Clark County, which has never encountered a bulldozer it didn’t like, has a dust problem and is under a maintenance agreement with the Environmental Protection Agency to regulate Particulate Matter 10 (PM10), also known as dust. Parking lots, with a few exceptions, must be paved. It’s been that way since 2003.
But that was before a two-decade long drought took hold of the Colorado River basin, making the threat of climate change as real as the ‘bathtub ring’ around Lake Mead.
No room for compromise
The existential threat of climate change hasn’t altered the county’s commitment to controlling dust, says county air control officer Marci Henson.
“We are not in a position to backslide on these commitments to enforce the maintenance plan and the air quality rules,” she says.
“It appears that Clark County is more intent on contributing to the climate crisis than contributing to stopping or reversing the heating,” says Paul Murad, a businessman who asked the county to allow him to test a cool pavement product on a 7,000 square foot downtown Las Vegas parking lot.
City of Las Vegas parking services manager Brandy Stanley wrote the county the city “will happily assist with any trial of the material.”
But Clark County air quality officials, who regulate the entire valley, say allowing the use of PolyPavement, the product proposed by Murad, would violate the county’s agreement with the EPA.
“It’s a non-permanent material and doesn’t meet the definition of paving (asphalt/concrete) in the air quality regulations,” Henson told the Current via email.
Curtis Reed of PolyPavement says the paving material is permanent and designed to last 12 to 15 years – twice as long as asphalt and about one-third to one-half of the cost, installed.
“Interestingly enough, our product was originally designed to be a PM10 eliminator,” Reed said. “I guarantee it would be acceptable to the EPA.”
The EPA says it doesn’t rate cool pavement products, but an agency document on heat islands says the “decreased energy demand associated with cool pavements will result in lower associated air pollution and greenhouse gas emissions. Cooler air temperatures also slow the rate of ground-level ozone formation and reduce evaporative emissions from vehicles.”
I think there are existing products that have made a lot of people a lot of money. When something better or new or different comes along, it's very difficult to introduce into a market that's already dominated.
– Curtis Reed, PolyPavement
“I am surprised, somewhat, at Clark County’s position,” Jeff VanEe, a former EPA pollution specialist, wrote via email. “As far as the connection to PM 10, I don’t get why that would be an impediment – other than the coatings may not wear as well as asphalt, and the particulates could further degrade our air.”
Reed says PolyPavement, which is applied to existing soil, is “twice as strong as asphalt, which breaks down in the sun, where an acrylic binder is made stronger in the sun.”
Heat island in the desert
Southern Nevada is a heat island, a phenomenon that occurs when cities become hotter than less-developed surrounding areas.
In the last decade, cities were 2.4°F hotter than their rural counterparts. But Las Vegas temperatures were up to 24°F higher in the city than in nearby rural areas during the summer.
Extreme heat can result in illnesses or even death. Scientists from the Desert Research Institute found that heat-related deaths in Clark County have significantly increased over the last few years, in large part due to the rise in extreme heat.
The county has relied on shade covering and tree planting to mitigate climate change. But an infrared NASA image reveals that from space, Southern Nevada streets resemble a red-hot waffle iron.
By replacing dark surfaces such as asphalt with lighter-colored materials, cities could reduce surface temperatures, if not air temperatures.
“The need, and the opportunity, are greatest in low-income and underserved communities, which tend to have more pavement and fewer trees than wealthier areas,” says the website for Global Cities, an organization that partners with more than two-dozen U.S. cities on cool initiatives.
Asphalt reflects about 12% of heat while cool pavements reflect between 33% and 38%, according to the City of Phoenix, which conducted a $3 million pilot program, applying a product called CoolSeal to 36 miles of asphalt roads. A specialized vehicle compared temperatures on treated and untreated roads at levels of one and six feet above the surface.
The program determined:
- Cool pavement revealed lower surface temperatures at all times of the day versus traditional asphalt.
- Cool pavement had an average surface temperature 10.5 to 12 degrees Fahrenheit lower than traditional asphalt at noon and during the afternoon hours. Surface temperatures at sunrise averaged 2.4 degrees Fahrenheit lower.
- Nighttime air temperature at six feet of height was on average 0.5 degrees Fahrenheit lower over cool pavement than on the non-treated surfaces.
The pilot program is being expanded.
Some critics suggest that painting streets white reflects heat on nearby bicyclists and pedestrians, as well as individuals living on the street. But the Phoenix study indicates the “human experience of heat exposure at noon and the afternoon hours” was “similar to walking on a typical concrete sidewalk.”
“While surface temperature reductions were strong, air temperature reductions were minor, yet influenced by numerous factors in an uncontrolled environment,” the study says.
Murad says only Clark County Commissioner Tick Segerblom was willing to go to bat for the test project.
“I think they just hate change and new ideas,” Segerblom told the Current of the county’s refusal to consider options.
“I had hopes for Commissioner Justin Jones,” Murad said, citing Jones’ participation in climate initiatives. But Murad said Jones had no interest in alternatives to asphalt for Southern Nevada’s sweltering streets. “I thought he’d get on board to embrace another option.”
Jones told the Current he was deferring to the county’s air quality officials.
Reed says he is at a loss to explain the county’s opposition, other than chalking it up to politics.
“In my experience, I think there are existing products that have made a lot of people a lot of money. When something better or new or different comes along, it’s very difficult to introduce into a market that’s already dominated,” he says. “So, I think it’s a very political thing.”
Las Vegas Paving, one of the largest beneficiaries of the government contracts that built Nevada’s 100,000 miles of paved roads, is in turn one of the largest benefactors of state and local politicians.
The company contributed $10,000 to Democrat Steve Sisolak’s gubernatorial campaign in 2017, $10,000 in 2018 to Home Means Nevada PAC, which supported Sisolak, $10,000 to Sisolak’s inauguration, and $10,000 to the governor in 2019.
LV Paving hedged its bet with a $10,000 contribution last year to Republican Joe Lombardo’s gubernatorial effort.
The company contributed $10,000 last year to Jones, and $5,000 in 2018. It’s also contributed $20,000 to Commissioner Marilyn Kirkpatrick since 2015.
The county recommended that Murad use another cool pavement, but has provided no alternatives or guidance on acceptable products. It also declined to provide that information to the Current and refused to answer additional questions.
“I can tell you that just about everything is in our metropolitan air – automobile engine traces, rubber tire particles, brake linings, asphalt fragments, etc. So why would coating our streets white make our PM 10 problem any worse?” asks Van Ee. “It seems to me Clark County doesn’t want to think progressively and they use PM10 as an excuse.”
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