Titanium Dioxide is a Short Term Solution to Cool Down Urban Heat Islands

As an environmental activist, it's crucial to make sure your activism is intersectional — climate change disproportionately affects BIPOC neighborhoods in a myriad of ways, between increased exposure to air and water pollution, disease, and food deserts. And now, a recent study is showing that BIPOC communities are also disproportionately affected by urban heat islands.

"Examining the relationship between the distribution of annual urban heat island exposure and income at the neighborhood level, find that the distribution tended to favor those with higher incomes in 18 out of 25 selected global cities," reads the study, which was published on Tuesday, May 24 in Nature Communications. "In 108 US cities... neighborhoods that were redlined in the 1930s have summer surface temperature profiles that are significantly higher than other coded residential areas."

NASA defines an urban heat island as a city that "experiences much warmer temperatures than nearby rural areas." It continues, explaining that "the difference in temperature between urban and less-developed rural areas has to do with how well the surfaces in each environment absorb and hold heat." Basically, because of heat-trapping building materials like asphalt, concrete, and brick, built-up cities tend to be much hotter than open rural areas — and the deeper you go, the hotter it gets.

Rural areas, on the other hand, tend to be covered in a wide variety of vegetation such as grass, trees, and flowers. Plants store water and release trapped vapor into the air in a process known as transpiration, which is effectively a natural air conditioner, cooling the air down on its own. That's why there are so many initiatives to create "green spaces" in cities right now — but sadly, more often than not, lower income neighborhoods are overlooked in these types of projects.

Although long term solutions to heat waves on urban heat islands would be to address heat risks by providing access to cool spaces, painting dark surfaces in bright, reflective colors, to create more green spaces like parks, plant more trees, and do more to curb greenhouse gas emissions. But right now, a company called Pavement Technologies, Inc. is testing a titanium dioxide-based spray for hot asphalt across major U.S. cities, according to Vice.

The spray effectively seals the top layer of asphalt, repairing road damage, lowering temperatures, and dissolving pollutants emitted from cars. The company is testing it on strips of road right now, to test the air quality and temperature of the asphalt. If it works, it could cool urban heat islands significantly. It will also reflect and absorb UV rays instead of heating up.

The study, titled Disproportionate exposure to urban heat island intensity across major US cities, was conducted by environmental economists such as Glenn Sheriff, Tirthankar Chakraborty, Diego Manya, and Angel Hsu. Using government temperature and census data, it found that white people are less affected by urban heat islands than non-white people — in 169 out of 175 major urban areas in the U.S. during summer 2017, the average person of color lived in an area more affected by urban island heat.

Those living in areas subjected to more urban island heat can experience much hotter days, warmer-than-usual nights, and increased air pollution, as per AP News, which can lead to more people experiencing heat stroke, respiratory difficulty, cramps, and exhaustion. Although money may be a factor, as lower income communities in general often aren't given green spaces, research also showed the average person of color is exposed to more heat island intensity than an average person living in poverty.

This is because people of color more often face discriminatory housing policies as well as redlining. Although green spaces might help some of these neighborhoods, it's mostly due to the fact that non-white communities are subjected to worse living conditions, which is a major ongoing issue that results from systemic racism. And, with increasing temperatures due to global warming, it's only going to get worse if something isn't done to tackle this issue.

There are many organizations that tackle intersectional environmental issues like these. (OPAL) Environmental Society, for example, is a grassroots organization gets BIPOC youth involved with organizing against issues like air quality concerns in marginalized communities and beyond. Hip Hop Caucus is another that educates BIPOC voters, advocating for action against environmental issues that disproportionately affect marginalized communities.

We also have an ongoing list of intersectional environmental activists that you can follow to stay up-to-date on issues like these. Urban island heat is just one example of the many ways environmental justice is important, and we must keep working to dismantle systemic racism.