Environmental Issues > Energy Main Page > All Energy Documents

  1. Why should I worry about my kids breathing diesel exhaust from their school bus?
  2. How much diesel exhaust gets into school buses?
  3. What are the health effects of diesel exhaust inside school buses?
  4. Do all school buses run on diesel fuel?
  5. Are the California buses you tested really like those that my child rides?
  6. Are all diesel buses equally dangerous?
  7. Should I keep my children off the school bus?
  8. What can I do to reduce my children's exposure to diesel exhaust?
  9. What's the best alternative to diesel-powered school buses?
  10. How can my school district possibly afford to replace its school buses?
  11. I've heard about "green diesel" -- is this also a good alternative?



1. Why should I worry about my kids breathing diesel exhaust from their school bus? After all, they ride inside the bus, not outside where the exhaust fumes are.

The truth is that tailpipe exhaust often dirties the air inside school buses -- sometimes in quantities far higher than are found outside the bus. And diesel exhaust is bad for your child: It contains carcinogens, as well as tiny particles that can cause or worsen breathing problems.


2. How much diesel exhaust gets into school buses?

To help answer this question, researchers from NRDC, the Coalition for Clean Air and the University of California at Berkeley measured air quality inside typical school buses as they traveled along real elementary-school bus routes in the Los Angeles area. They took continuous measurements inside the buses, and compared these to air quality both just outside the buses and in passenger cars traveling ahead of the buses tested. They took readings while idling with the motor running, while traveling up and down hills or driving slowly, and while making frequent stops. And most of the buses tested did not emit a significant amount of visible black smoke. In other words, the tests re-created real-life conditions.

The results were alarming. Our study found that levels of diesel exhaust inside a school bus can be four times higher than those found in passenger cars driving just ahead of the bus. And the diesel levels inside the buses were more than eight times the average diesel-exhaust content of California air.


3. What are the health effects of diesel exhaust inside school buses?

Diesel exhaust has serious health effects that have been extensively documented. For instance, numerous studies have shown that diesel fumes cause cancer, particularly lung cancer. In fact, government regulators estimate, based on lifetime risks, that diesel exhaust is responsible for 125,000 cancers nationwide.

Since children often ride buses to school every day for many years, their exposure adds up -- which translates into an unacceptably high risk of getting cancer later in life. Out of every million children that ride a school bus an hour or two each day during the school year, 23 to 46 of them may eventually develop cancer from the excess diesel exhaust they inhale on their way to and from school.

Other health effects are also troubling, though harder to quantify. The particles in diesel exhaust impair the lungs and aggravate diseases like emphysema and bronchitis; they can also worsen -- or trigger -- asthma attacks. What's more, children are more susceptible than adults to these effects -- they breathe faster and their lungs are less able to defend themselves from pollutants. In addition, exposures early in life can return to haunt them as they age, in the form of chronic health problems.


4. Do all school buses run on diesel fuel?

Not all, but most. The vast majority of the nearly half a million school buses in this country -- which carry more than 23 million children to and from school every day -- still use diesel fuel, even though less harmful fuels are available.


5. Are the California buses you tested really like those that my child rides?

The buses we tested, manufactured in the mid- to late-1980s, have the same engines and emissions controls as employed elsewhere in the country -- and remain in fairly common use in school districts across the country. California school buses may in fact run slightly cleaner than other school buses because the diesel fuel sold and used in California has lower sulfur content than average diesel fuel elsewhere in the country. But this difference would not likely change our assessment of the risk diesel exhaust poses to kids in general.


6. Are all diesel buses equally dangerous?

Older buses may have worse emissions than newer ones. Many school districts still use old models. Buses built in the mid- to late-1980s, for instance, are very common. There are school districts in California, Washington and Texas, for example, that are still using school buses more than 20 years old.

Age is not the only factor. Maintenance can also make a big difference -- two 1986 buses among our test fleet had very different levels of diesel exhaust inside.

The important point is that diesel buses carry unacceptable levels of risk for children. Whether a diesel bus is old or new, whether its tailpipe spouts black plumes of exhaust or emits no visible pollution -- diesel exhaust is simply dangerous to kids.


7. Should I keep my children off the school bus?

Although you should be concerned, you probably don't need to pull your kids off the bus. The health risks from diesel exhaust are related to the number of years children ride the bus. There's generally no need for children to stop riding school buses right away, but it is important for school districts to replace -- or at least retrofit -- the dirty diesel buses as soon as possible, so children aren't exposed to hazardous fumes for years.

For children with asthma or other respiratory problems, the situation may be different. If your child's symptoms seem to get worse on the school bus, consult your pediatrician -- it may make sense to explore finding other ways to get your child to and from school.


8. What can I do to reduce my children's exposure to diesel exhaust?

The best option is to push your school district to replace diesel buses with alternative-fuel buses (see below). But there are easy interim steps that lower your child's exposure to diesel fumes.

Our study found that levels of diesel exhaust inside buses are highest when the windows are closed. Also, when the windows are closed the exhaust accumulates in the back of the bus. Whenever weather allows, school bus windows should stay open.

Another helpful step is to have children sit toward the front. As children get on the bus to go to school, they should take the closest seat possible to the front of the bus -- children with the longest rides will thus be sitting in the part of the bus with the least exposure. They should get those same seats on the way home. Ask school officials, bus companies and bus drivers to follow these simple steps.

A further interim step is to modify your school district's buses to make them less polluting. Devices that trap particulates can be installed on buses that run on low-sulfur diesel fuel, which is currently available only in limited supplies in a few areas. If you live in one of them -- southern California, the San Francisco Bay Area, Houston or New York City -- you can urge school officials to install particulate traps. Keep in mind, however, that although particulate traps do reduce emissions, they have not been proven to reduce harm to children; they are not a substitute for converting to cleaner buses. (New federal rules will make low-sulfur fuel more widely available, but this process will take several years.)


9. What's the best alternative to diesel-powered school buses?

Buses that run on compressed natural gas and propane are much cleaner and just as reliable. More and more school districts are turning to these kinds of buses. Research on alternative fuels and technologies continues; other alternatives -- including battery- or fuel-cell-powered buses and buses that run on a combination of fuel and batteries -- may be on the horizon.


10. How can my school district possibly afford to replace its school buses?

There's no doubt about it -- a new school bus is a big-ticket item. But there are many local, state and federal funding sources that can help offset the additional up-front costs of buying alternative-fuel buses. (See Chapter 7 of NRDC's report No Breathing in the Aisles for more information.) Still, more funding is needed to convert all of our nation's school-district fleets to cleaner fuels, and parents should urge federal, state and local policymakers to make replacing old, dirty-diesel buses a top priority in their budgets.

Alternative-fuel buses are more expensive to buy, but they can cost less to run and maintain -- over time, a school district can recoup the initial cost of switching over. Additional long-term savings that cannot be ignored: the drop in health-care costs that will result from fewer children being exposed to harmful levels of diesel exhaust.


11. I've heard about "green diesel" -- is this also a good alternative?

So-called green diesel is an improvement over existing diesel technology, but it is still dirtier than alternative-fuel technologies. Most important, it hasn't been proven to sufficiently reduce the cancer risk associated with diesel emissions. There's another drawback: green-diesel technology hasn't been certified by any government agency -- and even when certified, it won't be an option for most school districts until at least 2006 due to the limited quantities of the low-sulfur diesel fuel it depends on. "Green diesel" is no substitute for cleaner fuels.

last revised 3/17/2001

All Tags [ View Popular Tags ]:
60mpg
AB 1493
AB 32
agriculture
air pollution
air toxics
alabama
algae
alternative fuels
AnthonySwift
Appalachia
appliances
Arctic
Arctic National Wildlife Refuge
asthma
automakers
aviation
beaches
biochar
biodiesel
biofuels
biogas
biomass
birds
boreal forest
BrianSiu
budget
CaiSteger
California
California environmental legislation
Canada
cap 2.0
cap and trade
carbon footprint
carbon offsets
carbon pollution
cars
case studies
causes of global warming
CCS
CFLs
Chile
china
CHP
Clean air
Clean Air Act
clean energy
clean energy economy
clean vehicles
cleantech
climate
climate change
climate legislation
clothes dryers
coal
coal-fired power plants
compact fluorescent lighting
compact fluorescents
computer equipment
Congress
consumer products
coral
cover crop
CPS
DabbieHammel
Danielle Droitsch
DanielleDroitsch
data centers
DebbieHammel
deforestation
demand side management
DerekMurrow
DevraWang
DianeBailey
diesel
diesel buses
diesel exhaust
dirty fuels
dod
dolphins
drilling
economy
efficiency
efficient light bulbs
efficient vehicles
electric cars
electric utilities
electric vehicles
electricity
electricity and natural gas utlities
ElizabethShope
emissions
energy efficiency
energy efficiency standard
energy efficient buildings
energy efficient light bulbs
energy effiency
energy plan
energy policy
energy security
energyappropriations
energyapprops
energy-efficient bulbs
environmental history
environmental protection agency
EPA
ethanol
finance
fish & fishing
FL
florida
Forests
fracking
fracking risks
FranzMetzner
fuel
fuel economy
fuel efficiency
fuel efficiency standards
fuel savings
gas drilling
gas prices
gasoline
gis
global warming
global warming and the economy
global warming emissions
global warming legislation
global warming pollution
globalwarming
green building
green buildings
green business
green jobs
green sports
greenhouse gas emissions
Gulf
gulf of mexico
gulfofmexico
gulfspill
halogen bulbs
halogen lightbulbs
health
health effects
home energy
home networks
household energy use
HUD
human health
Hurricane Katrina
hybrid
hybrid cars
hybrid electric vehicles
hybrid vehicles
hybrids
hydraulic fractring
hydraulic fracturing
hydrogen
incandescent lighbulbs
incandescent light bulbs
India
India Initiative
indoor air quality
infrastructure efficiency
interiorappropriations
interiorapprops
JacksonMorris
jobs
KatharineMcCormick
keystone
Keystone XL
Kids' Health
KXL
Latin America
LCFS
lead
LEDs
light
light bulbs
light emitting diodes
liquid coal
livestock farms
location efficiency
Los Angeles
louisiana
LukeTonachel
mapping
Marcellus Shale
Massachusetts
mercury
methane
Mexico
mid-Atlantic
Middle East
mining
mississippi
Missouri
Montana
mountains
mountaintop removal mining
mtr
natural gas
natural gas drilling
NEPA
New York
Nigeria
nitrogen oxides
NoahHorowitz
North Dakota
Northeast states
nrdc offices
nuclear energy
oceans
offshore
offshore drilling
offshore oil
ohio
oil
oil and gas industry
oil consumption
oil dependence
oil drilling
oil imports
oil shale
oil spill
oil spills
oilspill
OPEC
open space
ozone
particulate pollution
pennsylvania
Persian Gulf
photos
PierreDelforge
pipeline
policy
pollution
power plants
PTC
public lands
public transportation
rail
refrigerants
regional greenhouse gas initiative
regulatory reform
renewable energy
renewable fuel
renewables
residential small networks
respiratory illness
RGGI
riders
Rocky Mountains
RPS
Russia
SB 315
schools
server rooms
shell
smart biomass
smart grid
smart growth
smog
smog air pollution
solar
solar power
solutions
soot
Southeast
sulfur dioxide
SusanCasey-Lefkowitz
sustainable sourcing
tar sands
tar sands pipeline
tar sands; keystone xl
tax incentives
tax subsidies
television
tennessee
texas
toxic waste
trailbreaker
transit
transportation
transportation bill
trasnportation
tv
tvs
utilities
VEETC
vehicle
vehicle emissions
vehicles
Venezuela
video game consoles
wastewater
water efficiency
Water Pollution
wetlands
whales
what you can do
wind
wind power
wind turbines

Sign up for NRDC's online newsletter

See the latest issue >

Give the Gift That Will Make a Difference: Renewable Reality

NRDC Gets Top Ratings from the Charity Watchdogs

Charity Navigator awards NRDC its 4-star top rating.
Worth magazine named NRDC one of America's 100 best charities.
NRDC meets the highest standards of the Wise Giving Alliance of the Better Business Bureau.


Donate now >

Related Stories

Efficient Appliances Save Energy -- and Money
A consumer's guide to buying energy efficient appliances and electronics.
Share | |
Find NRDC on
YouTube