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Study finds that replacing older, highly polluting school buses could lead to 1.3 million fewer daily absences annually

Replacing all of the oldest, highly polluting school buses in the US could lead to 1.3 million fewer daily absences annually, according to a University of Michigan study. The suspected cause of these preventable absences is exposure to high levels of diesel exhaust fumes, which can leak into school bus cabins or enter buses through open windows.

Over time, exposure can exacerbate respiratory illnesses and other conditions and lead to missed school days, say the researchers on the open-access study, which appears in the journal, Nature Sustainability.

Even relatively short commutes on school buses can dominate students’ daily air pollution exposures.

—Meredith Pedde, lead researcher

The study is the first to evaluate the effectiveness of the Environmental Protection Agency’s School Bus Rebate Program, which launched in 2012, Pedde said.

It is well established that traffic-related pollutants can have harmful effects on the body such as inducing inflammation, reducing lung function and increasing asthma attacks. Given the EPA’s random allotment of its clean bus funding, we believe our research clearly establishes the link between upgrading school buses and student attendance. Moreover, it demonstrates the need for continued and increased support for school districts to replace or upgrade their buses.

—Meredith Pedde

The researchers analyzed data from nearly 3,000 school districts that applied to the EPA’s school bus replacement funding program between 2012 and 2017 and compared changes in attendance rates in 383 school districts that received funding and 2,400 districts that did not.

On average, they found that districts with upgraded buses had a 0.06 percentage point higher attendance rate compared to districts not selected for the clean bus funding. In a district of 10,000 students, that change means six additional students attended school each day. In total, replacing older school buses with newer models prevented at least 350,000 absences in one year in schools across the country.

In districts with higher levels of estimated ridership on replaced buses and older fleets of buses, the numbers were higher, with 14 more students per day attending school in high ridership districts and 45 more students attending each day in districts that replaced buses built before 1990.

Applying their results nationwide, the researchers extrapolated that replacing all pre-2000 model school buses would lead to more than 1.3 million additional days of attendance a year.

Approximately 25 million children ride buses to school in the US each year. While it is considered the safest mode of transportation from a traffic accident perspective, concerns about levels of emissions are well documented.

The EPA set out to hasten the transition of school bus fleets to cleaner vehicles in 2012 with its School Bus Rebate Program. The program is ongoing. It provided an average of nearly $6 million annually to school districts to upgrade school buses with cleaner alternatives during the period covered by the study.

The cost of upgrading buses—about $10,000 to retrofit and between $100,000 and $300,000 to purchase new buses—puts districts in the position of using buses as long as possible.

The average bus is on the road 16 years before it is decommissioned. That means millions of children are still riding older, highly polluting buses to school. These findings demonstrate the importance of continued funding for new, clean school buses since we saw measurable improvements in attendance when school districts update their buses. Most importantly, we found that replacing the oldest buses will result in the largest benefits for children and their caregivers.

—Sarah Adar, co-author


  • Pedde, M., Szpiro, A., Hirth, R. et al. (2023) “Randomized design evidence of the attendance benefits of the EPA School Bus Rebate Program.” Nat Sustain doi: 10.1038/s41893-023-01088-7



I am very surprised by this study, which is actually only intended to support BEVs and trucks with petrol engines.
I'd like to ask - what do the Smog Centers do when they check the exhaust emissions of school buses? Don't they check anything?
Furthermore, it is known that leaking exhaust systems are illegal! Furthermore, the exhaust must end at the back of the school bus and not somewhere between the front and the back.
It is also very important that the exhaust end is angled 90 degrees downwards. Also an inflow of air in the rear area of the exhaust pipe is technically simple to build and it is legal!

And the air quality inside the school buses!
It amazes me that the windows of the buses are open in the USA! In Europe, the windows are always closed as a rule! That's why no exhaust fumes or other dirt like that from trucks gets into the buses. By the way, every bus has a very good air conditioning system that also filters the air. So I can't imagine that this new study was created neutrally as it is full of mistakes from theorists who have never driven on a bus or know their technology!!!

Unfortunately, these studies are increasingly flawed and pro BEV! Unfortunately not neutral as one would expect in a democracy!


This article sheds light on the impact of pollution on students' health and academic performance. The study highlights that replacing old, highly polluting school buses with newer and cleaner ones could significantly reduce the number of daily absences, resulting in a positive impact on students' education.

This issue of air pollution and its impact on education is not a new one, as researchers have been examining the link between environmental factors and academic performance for many years. As the article suggests, it is important to invest in clean energy and technology to reduce air pollution and create a healthier environment for students to learn and grow.

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Overall, this article and the issue it highlights remind us of the importance of taking action to improve the educational environment for students. By investing in clean energy and reducing pollution, we can create a healthier and more equitable learning environment for all. For those interested in learning more about the topic of oppression and its impact on education, the StudyDriver resource on "oppression essay" may provide valuable insights.

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