THEGREENGROK    Statistically Speaking

Statistical Grok: School Buses and Pollution

by Bill Chameides | August 29th, 2008
posted by Erica Rowell (Editor)

Permalink | 2 comments


School buses can expose children to some 40 hazardous pollutants. New buses are cleaner, but with so many old buses still in use communities should look to retrofits that slash pollution levels or new buses.

Numbers can tell stories. School buses — mass transit for students — are overall better for the environment than millions of cars transporting kids to school. But we need to clean these buses up — and I don’t mean taking them to the car wash.


Approximate number of children that ride buses to school:
25 million

About how many hazardous substances (ranging from smog-forming pollution to soot) affect the air quality of diesel school buses:

How much more air per pound of body weight children breathe than adults:

Estimated number of cancers diesel exhaust is responsible for nationwide:

Estimated number of children* that may develop cancer from the air they inhale while on a school bus:
23 to 46 out of every million


When during a school bus ride levels of fine particulates and black carbon are highest:
when buses are queued and idling

What idling for one hour a day costs in terms of engine wear and fuel use, respectively:
1,260 miles per year and half a gallon per day

Approximate number of U.S. school buses in operation:

How much cleaner a bus retrofitted with pollution filters is compared to a typical bus:

Number of retrofitted buses:
more than 12,000

Estimated number of pre-1990 school buses on the road:

How much cleaner model year 2007 school buses are than those built before 1990:
more than 90%

* Who ride school buses an hour or two each day



American School Bus Council –

Bus Registrations, 2006 –

Environment and Human Health, Inc. – and

“Diesel Bus Emissions Prompt School Officials Into Action,” Environmental Bulletin (A Maine Environmental Bulletin for Maine Citizens and School Officials) –

“A Multi-City Investigation of the Effectiveness of Retrofit Emissions Controls in Reducing Exposures to Particulate Matter in School Buses,” Clean Air Task Force –

Natural Resources Defense Council –

Regulatory Announcement, Environmental Protection Agency –

Replacing Old School Buses – What School Districts Should Consider, Environmental Protection Agency –

Selecting Buses with the Most Up-to-Date Environmental Controls and Safety Measures,” Environmental Protection Agency –

“American School Bus Council Encourages School Age Children to Ride the School Bus,” Apr 21, 2008, Reuters –

Further Reading

“Diesel Solutions,” Puget Sound Clean Air Agency –

National Clean Diesel Campaign, Environmental Protection Agency (EPA) –

Clean School Bus, EPA –

Replacing Old School Buses – What School Districts Should Consider, EPA –

filed under: faculty, health, Statistically Speaking
and: , , , ,


All comments are moderated and limited to 275 words. Your e-mail address is never displayed. Read our Comment Guidelines for more details.

  1. Daniel Wedgewood
    Sep 10, 2008

    Your argument strongly suggests that there would be enormous health benefits (long term, at least) from retrofitting. Why wouldn’t the health insurers pay to have the buses fixed, since it would save them huge amounts of money later on? Many insurers, I think, already pay subscribers for exercise programs and other kinds of preventive measures… – Dan” title=”Why aren’t the insurers paying?

    • Erica Rowell
      Sep 11, 2008

      Dr. Chameides responds – Dan, With regard to insurers paying for retrofits: great idea. Why don’t they do it? Good question. And the government is doing things. There is a federal program to help states and municipalities retrofit school buses and there are a number of NGOs working to make the retrofits happen faster. Some think things are proceeding fast enough; others don’t. Your call on where you think things stand and what to do about it.” title=”Insurers paying for retrofits

©2015 Nicholas School of the Environment at Duke University | Box 90328 | Durham, NC 27708
how to contact us > | login to the site > | site disclaimers >

footer nav stuff