The American Lung Association’s 2019 “State of the Air” report released in April ranked Houston ninth nationally for worst ozone pollution and 17th for particle pollution.

But Cornell researchers express hope for the future of Houston’s breathable air: By replacing at least 35% of Houston’s gasoline cars and diesel trucks with electric vehicles by 2040, Houstonians could breathe easier, live longer and enjoy a better economy.

“The built environment plays a significant role in affecting our daily life and health,” said H. Oliver Gao, professor of civil and environmental engineering and senior author of “Potential Impacts of Electric Vehicles on Air Quality and Health Endpoints in the Greater Houston Area in 2040,” published in Atmospheric Environment.

Gao, who directs Cornell’s Center for Transportation, Environment and Community Health and is a fellow at Cornell’s Atkinson Center for a Sustainable Future, said that more than two-third of the oil imported by the U.S. is used for transportation.

Credit: Jason Koski/Cornell University

“While transportation provides us with mobility, it impacts our environment and our public health,” he said. “We are enjoying this mobility at a very high cost.”

Shuai Pan, postdoctoral associate in civil and environmental engineering, along with Gao and a team of chemists and engineers, modeled four scenarios using various levels of electric car adoption to see how Houston’s air quality and public health likely would respond two decades from now.

The researchers examined Houston’s daily 8-hour average ground-level ozone concentrations. The four scenarios they modeled were:

• keeping business-as-usual;
• moderate electrification (35% electric);
• aggressive electrification (70% electric); and
• complete turnover (35% electric, plus 65% potentially newer combustion and emission control technologies).

For surface ozone in 2040, the business-as-usual model showed elevated parts-per-billion concentrations. In the moderate and aggressive electrification scenarios, the models showed substantial improvement by reducing surface ozone parts-per-billion. With nearly complete turnover (about 95% reduction in emissions), that model showed a decrease of 3 to 4 parts per billion of surface ozone over most of Houston.

Currently, ozone “design value,” a regulatory statistic, is about 80 parts per billion in Houston; the modern standard is 70 parts per billion. “A decrease of 3 to 4 parts per billion of average ozone – from on-road mobile sources, for example – would be considered a large improvement,” Pan said.

The authors note that Houston’s population is projected to increase by 50% by 2040, which will increase motor vehicle activity and double the number of trucks. The Texas Transportation Institute projects the number of gasoline vehicles will increase by 30% to 50%, and the number of commercial trucks will increase by 40% to 80%.

“There are atmospheric implications on this,” Gao said. “Cities and regions are in need of policies that will help push electrification, so that we can … gain health benefits and improve air quality.”

Pan said that even if its vehicle population almost doubles by 2040, Houston will likely have a much smaller emission factor than today, thanks to zero-emission technology at the systems level.

“The population in 2040 Houston will see a huge increase, but we can apply new technology to reduce emissions, improve air quality and think about health,” said Pan, who earned his Ph.D. in atmospheric science from the University of Houston in 2017.

The researchers note that although charging stations for electric vehicles will be added to the power grid, power resources should not be burdened. There is little need to build more power plants, the researchers said.  

In their exhaust, gasoline and diesel vehicles emit nitrogen oxides – volatile organic compounds that react in the presence of sunlight to form ozone and increase detrimental fine particulates, elements known to harm human health.

If left unchecked, current ozone and particulate-matter levels would result in 122 more premature deaths annually throughout greater Houston by 2040. With moderate or aggressive electrification for cars and trucks, the numbers reflect air-quality improvement, with prevented premature deaths at 114 and 188, respectively.

In the case of complete turnover to electric vehicles, the number of prevented premature deaths per year around Houston shoots to 246.

“Mayors or policymakers – who care about the environment, the economy and public health – must advocate for electrification,” Gao said. “The knowledge is there, but we need mayors and city planners to be creative and innovative to design policies that would help the electrification of the transportation sector.”

Other contributors were Yunsoo Choi, associate professor of atmospheric chemistry, postdoctoral fellow Anirban Roy and doctoral candidate Ebrahim Eslami, all of the University of Houston; Stephanie Thomas, Public Citizen, a nonprofit public advocacy organization; and Xiangyu Jiang, University at Buffalo.

Funding for this work came from the U.S. Department of Transportation.