In recent decades, the way Americans buy things has undergone a radical transformation. E-commerce firms like Amazon have reshaped how people shop and how they receive their purchases, dotting the country with gigantic warehouses for the distribution of merchandise and bringing high volumes of truck traffic to nearby communities.
In a paper published Wednesday, researchers at George Washington University used satellite data to measure the air pollution associated with large warehouses — the first such nationwide study.
The researchers focused in part on nitrogen dioxide, or NO2, a traffic-related air pollutant that is regulated under the Clean Air Act and is linked to asthma and other respiratory diseases. The study, which was funded by NASA, cross-referenced the locations of 150,000 warehouses across the U.S. with satellite observations of NO2 and found that people who live near warehouses are exposed to an average of 20 percent more NO2 than those who don’t. It also found that warehouses are located disproportionately in Black, Hispanic, and Asian neighborhoods — and that the concentration of racial minorities was closely correlated with the number of warehouses in a given area. Over 250 percent more Hispanic and Asian residents live near the largest warehouse clusters than the national average.
The highest concentrations of NO2 pollution are one or two miles downwind of the warehouses, said Gaige Kerr, the study’s lead author. This reflects the fact that NO2 is not directly emitted by vehicles. Instead, Kerr said, “Tailpipes emit NO, nitrogen oxide, and then NO undergoes chemical reactions in the atmosphere. Those reactions take a little bit of time, so the result of that is, you can imagine, there’s this plume of NO-rich air at the warehouse and it’s blown by the prevailing winds.”
Warehousing is as old as the shipping of goods, but Kerr said the growth of online retail has transformed an industry that had looked the same for decades. “If you look at a plot of warehouse characteristics over time, the average new warehouse built from about 1980 to 2010 all kind of are the same,” Kerr said.
But then everything changed. “Following 2010, there is a really dramatic increase in the average square footage of warehouses,” Kerr said. “There’s about a 400 percent increase in the number of loading docks at the average warehouse, and also increases in the number of parking spaces as well as the density of warehousing clusters.”
With the growth of these facilities came organized community opposition in some of the country’s biggest warehouse hubs. In California’s South Coast, home to the largest concentration of warehouses in the country, local regulators adopted a landmark pollution rule in 2021, requiring warehouses to offset pollution from their trucks by choosing from a suite of actions including adding electric vehicle chargers or solar panels, or paying a mitigation fee to fund clean energy investments in the affected communities.
This rule was novel in its recognition of warehouses as an “indirect source” of pollution: Even though the buildings themselves didn’t emit pollutants, their owners were now on the hook for the pollution from the traffic they brought. Other states have begun considering implementing versions of this rule.
Kerr said there are policy solutions available at a variety of jurisdictional levels to lessen the health impacts of warehouse pollution. Besides issuing emissions limits, the federal government can further incentivize the electrification of trucks. But other players can do their part as well: “Individual corporations can pledge to phase out some of their older diesel vehicles, which are the worst when it comes to pollution. And there can also be commitments from electric utilities to deploy charging infrastructure, especially near clusters of warehouses and in really heavy trucking corridors,” Kerr said.
Americans could also buy less stuff.
