School Buses Are Terrible for the Environment, and Texas Is Sort of Doing Something About It

Categories: Environment

Ahh, so many fond memories of the yellow dog school bus. So much wheezing, coughing, and killing of the ozone layer. Those were the days.

We already knew that North Texas' air is terrible. The ground isn't much better.

And according to the EPA, school buses may have a lot to do with that ground pollution. A school bus can emit nearly twice as much pollution per mile as a semi-truck, and it doesn't help that the kids who ride them, with their younger and developmentally sensitive respiratory systems, typically take in more breaths than adults.

That's why the state is offering to foot the bill for ditching old diesel-engine vehicles and replacing them with new hybrid or alternative fuel vehicles -- and why the state is looking toward Dallas as a prime candidate.

The program is called the Texas Clean Fleet Program, and it's a grant under the umbrella of the Texas Commission on Environmental Quality (TCEQ). Any business, school district, government entity, or rig hoarder with at least 75 diesel vehicles can apply for the grant. The organization must be planning to replace at least 20 vehicles, and can replace all the vehicles, with hybrid ones.

Only areas where ground ozone levels desperately need reducing are eligible. According to the TCEQ, Dallas is listed listed a "nonattainment area," or a region where local emission levels have failed to meet federal standards (although we've pretty much routinely violated the Clean Air Act for the past seventeen years).

Dallas County Schools is the 4th largest provider of school buses in the country, serving 11 districts in the area -- and most of these vehicles run on diesel fuel. Replacing Dallas County Schools' diesel buses could have a huge impact on helping Dallas reach federal clean air compliance standards.

"The grant status is for counties for the ground level ozone to reach attainment," Joe Walton, spokesman for the Texas Emissions Reduction Program with TCEQ, told Unfair Park. "We focus on these areas and other counties [that are] approaching nonattainment."

"It incentivizes going from older, dirtier diesel engines to cleaner engines," says Walton. And it incentivizes Dallas County Schools to replace their yellow bus jalopies with shiny, new, environmentally-friendly transportation. Not to mention make cleaner breathing air for roughly 425,000 area students.

Walton says that he expects about half the grant applicants to be school districts. If you're picturing a fleet of Prius school buses, though, think again. The TCEQ will only fund 80 percent of the replacement costs, and it's up to the grant recipients to pay the remaining cost.

"We have already starting looking into this grant to see if we qualify and how many vehicles we will have the opportunity to replace," David Escalante, a spokesman for Dallas County Schools, which operates buses for DISD and other county districts, told Unfair Park in an e-mail. "This grant would help to replace the older diesel engine buses and help reduce the amount of nitrogen dioxide (NOX) emissions that they put into the atmosphere compared to the cleaner new diesel buses."

Walton concurs that the grant would be an help reduce NOX emissions produced by the thousands of metroplex school buses, which are both harmful to the ground level ozone layer and to childrens' developing respiratory systems. He says that previous emission reduction programs have had some effect on DFW emission levels. "Emissions are cleaner in Dallas than they have been in past years," he said. "So these programs do have an effect."

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Hopefully the CNG buses have improved since the last go round.  My wife worked for the transportation department field trip office for one of the local school districts about 15 years ago.  She often had to drive a bus when they ran out of drivers and was just as often stuck with one of the districts few remaining CNG buses.  The CNG bus did not have the acceleration, range or reliability of the diesel buses.

RTGolden1 topcommenter

Dallas County Schools already has an alternative fuel source and the infrastructure to deliver it, in place.  Propane, which burns cleaner than clean diesel, doesn't require cryo-storage like Nat gas and produces far far fewer pollutants than diesel or gasoline.  DCS has a bulk tank and pumps at the lawnview yard and the other bus yards are served by bottle trucks.  It would be far cheaper to switch to propane buses than clean diesel as well, some large trucking companies are already switching their city trucks (non-sleepers) over to propane for the financial benefits.  In addition to tax breaks, there is reduced maintenance cost since the fuel burns so much cleaner, and with the newer, high efficiency propane engines, there are savings on fuel costs without the loss of power that previously plagued propane-fueled vehicles.

Either move is a good move, but why not make the better move?


Can they be fitted with the new exhaust reactors instead of replacing the whole fleet?


Replacing the older buses with new clean diesel buses is a good environmental and fiscal decision.

An analysis by the Clean Air Task Force compared 2012 CNG to 2012 clean diesel buses, which is significant because the natural gas industry often compares 2012/13 CNG buses to older diesel technology to inflate the CNG environmental advantage. 

The reality is new clean diesel technology is very competitive with CNG – in a much more cost-effective manner.

2012 Clean Diesel Bus/2012 CNG Emissions Comparison To 2000 Diesel Bus
Nitrogen Oxide Particulate Matter Hydrocarbon
(NOx) (PM) (HC)
2012 Diesel Bus -94% -98% -89%
2012 CNG Bus -80% -99% -100%
(Source: Clean Air Task Force - “Clean Diesel versus CNG Buses: Cost, Air Quality, & Climate Impacts”)

The analysis: “Both new diesel and new CNG buses have significantly lower emissions of NOx, PM, and HC than the older diesel buses that they replace. According to EPA’s MOVES emissions model a 2012 model year diesel bus emits 94% less NOx per mile, 98% less PM, and 89% less HC than a model year 2000 (12-year old) diesel bus. A model year 2012 CNG bus emits 80% less NOx, 99% less PM, and 100% less HC than a model year 2000 diesel bus.

Emissions Reductions Per 10 Replacement Buses (compared to 2000 diesel buses)
Nitrogen Oxide Particulate Matter Hydrocarbon
2012 Diesel -4,953 kg -275 kg -429 kg
2012 CNG -4,197 kg -279 kg -471 kg

Replacing 10 older diesel buses with new diesel buses will reduce annual NOx, PM, and HC emissions by 4,953 kg, 275 kg, and 421 kg respectively. Replacing 10 older diesel buses with new CNG buses will reduce annual NOx, PM, and HC emissions 4,197 kg, 279 kg, and 471 kg respectively. On a per-bus basis new CNG buses provide slightly greater PM and HC reductions, but lower NOx reductions,than new diesel buses.”


Proud to say that Downwinders at Risk, through its Holcim settlement-endowed Sue Pope Fund, donated the first hybrid school bus in North Texas to the Midlothian ISD five years ago. Figured the kids there needed the break.


First! (the sort of person who, as a kid, was first on the school bus, too)



Jim, you and your group have been doing good for many, many years. In this case, you put money where the kids' mouths and noses are. I know your victories are hard-won, and you don't get nearly the recognition that you should (hope there's a plaque on that bus somewhere, maybe inspire some kid to join the cause later.)

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