Over the past eight years, I have studied air pollution of the United States and other countries around the world. My career has been centered around using high-performance computer models to identify the biggest air pollution offenders. The air pollution research community is well aware that the U.S. diesel truck fleet has the potential to spew hundreds of thousands of tons of air pollutants each year, if left uncontrolled.
Thankfully, over the past few decades, the U.S. government has made excellent strides in regulating heavy-duty diesel pollution in the form of emissions standards. So, when I was informed by UCS advocates that EPA Administrator Scott Pruitt proposed last November to allow glider vehicles to be exempt from modern emission control standards, I was floored. To be completely honest, I was angry.
You’re probably wondering what a glider vehicle is and why this action made me so upset. Glider vehicles are heavy-duty trucks with new bodies and refurbished engines with old or non-existent emissions control technology. Engines in these trucks can date back to the 1990s. The proposal would exempt glider vehicles from the current emissions standards that are in place for new heavy-duty trucks. This loophole has been exploited by a few small manufacturers, and the industry has grown exponentially over the last 6-8 years.
Effective emissions testing
EPA’s proposal cited a glider manufacturer-funded study by Tennessee Technological University (TTU), which claimed that glider vehicle emissions were no worse or even better than those from modern engines. The study has since been renounced by TTU President Philip Oldham for its questionable methods and execution.
So, how should heavy-duty engine emissions be tested? This is no small task as testing requires expert operation of advanced equipment. The air pollution community has published several peer-reviewed studies about proper emissions testing practices. Effective emissions rate testing involves simulating cycles for many scenarios: cold start, congestion-related stop and go traffic (creeping), arterial road traffic (transient), and highway cruising. Emissions testing on glider vehicles should be held to these standards, and lawmakers should be wary of testing that shortcuts trusted practices. The now renounced TTU study did not use standard test cycles during their glider vehicle testing, they did not repeat their trials, and PM2.5 emissions were subjectively quantified by visual inspection. Subsequently, a proper study was conducted by an EPA staff member in Ann Arbor, and particulate emissions from the glider engines were so high that the testing equipment shut down. Clearly, the petition did not have a solid study to stand on.
Diesel pollution has real effects on human health
Detailed studies have been published in well-respected journals by researchers in the air quality community to understand the links between diesel exhaust exposure and human health. I was fortunate to take part in a major collaboration between Georgia Tech and Emory University to investigate the links between air pollution and health in the southeastern United States. My colleagues at Emory University showed that the odds of preterm birth for expecting mothers increases with increased exposure to traffic-related air pollutants, nitrogen dioxide (NO2) and elemental carbon (component of soot). NO2 and soot are the glider vehicle pollutants of greatest concern.
Health effects from exposure to pollutants can be estimated with reactivity tests that measure oxidant production potential. Oxidant production within the body creates an imbalance with anti-oxidants, leading to the breakdown of cellular material and the disruption cell homeostasis. Inhaled pollution has been linked to oxidant-generation potential in the lungs, causing inflammation and decreased lung capacity. My colleagues at Georgia Tech found that in Atlanta, GA, heavy-duty diesel pollution was estimated to cause approximately 14% of oxidative potential. Allowing more glider vehicles into the heavy-duty truck fleet increases the risk of respiratory and gestational ailments for susceptible individuals living or working near highways.
Low-income neighborhoods hurt most
Further, allowing more dirty diesel vehicles on the road will reverse pollution reductions, especially near highways. Frankly, this is what makes the proposal so dangerous. The likelihood of living near a highway increases with decreasing median household income. Therefore, an increase in roadway pollution from poorly-regulated engines would disproportionately affect poorer neighborhoods with fewer healthcare resources. People of color who already have higher risks for ailments, such as asthma and heart disease, also tend to live closer to highways. So, while the proposal will save truck owners from paying for modern emission control technology, poor people and people of color will most likely bear the heaviest public health burden if the proposal goes into effect.
Stop dirty diesel
Simply put, the glider vehicle proposal should not go forward. The emissions study cited by the proposal was poorly conducted (and ultimately withdrawn), poor people and people of color will suffer from increased roadway pollution, and susceptible groups will have increased health risks. Please let science lead this cause. Slightly cheaper trucks are a terrible substitute for human health.
Organizations: American Geophysical Union; American Association of Aerosol Research, 500 Women Scientists