As kids across the country hop on buses and head back to school, what else are they taking in besides an education? The answer may be pollutants.

School buses, typically powered by diesel engines, can emit dangerous levels of pollutants. Children are particularly vulnerable to the health effects of these emissions. A 2001 study by the Natural Resources Defense Council found that children in the back of diesel-powered school buses could be exposed to toxic pollutants at four times the rate of people in the cars behind those buses, and that riding in school buses powered by diesel could pose 46 times the rate of “significant” risk for cancer. A more recent 2015 study for the California Air Resources Board found that air pollution in diesel-powered school buses continues to put children in danger. The negative effects range from heightened absenteeism to persistent heart and lung conditions, such as emphysema and asthma.

Efforts to improve the tailpipe emissions of school buses could have wide-reaching effects. More than half of all U.S. students, or greater than 25 million children, ride in school buses. A 2015 study by the University of Michigan found that reductions in diesel tailpipe emissions had widely positive effects on children, from improved lung functions to reduced absenteeism.

One straightforward method of eradicating tailpipe emissions would be for school districts to adopt all-electric buses.

All-electric buses that plug in to the electric grid virtually eliminate children’s exposure on school bus trips to dangerous pollutants such as nitrogen oxides and volatile organic compounds. The buses also safeguard children’s futures by reducing greenhouse gas emissions that are contributing to climate change. A switch to electric buses provides a double win of protecting our kids’ health and their environment.

Electric school buses have recently become available in the North American market. Only a few companies manufacture purpose-built electric school buses, but some school districts in the United States and Canada have committed to deploying them. Quebec company Lion manufactures electric school buses, and U.S. bus maker Blue Bird plans to produce electric school buses by the end of 2018 that will be able to put power back onto the grid or into a building. The capacity to operate buses with two-way power would improve the financial outlook of purchasing electric buses, which are more expensive to purchase but are less expensive to fuel and operate.

U.S. interest in electric buses is growing, although mostly for use in public transit systems (Los Angeles, for example, plans to switch its entire transit bus system to electricity by 2030). Recently, city planners have expressed the need to expand the benefits of zero-emission electric buses, such as better air quality and helping develop neighborhoods, to low-income residents and vulnerable populations. Falling battery prices and the introduction of new electric bus manufacturers to the school bus market will help extend these trends to school districts. Children, among the most vulnerable of groups, may soon be enjoying the quiet, pollution-free benefits of electric transportation.