Report cites hazards of idling school buses

Report cites hazards

of idling school buses

Sevier County education system has taken steps to clear air, but Knox hasn't

BY SCOTT BARKER
barkers a knews.com

When buses idle outside school buildings, harmful emissions can build up inside the passenger compartments where children sit waiting to go home.

Tiny particles of soot spewing from the diesel engines swirl through open doors and windows. The fine particles — 1/30th the diameter of a human hair or smaller — can lodge deep in the lungs, exacerbating breathing conditions such as asthma.

The Sevier County school system has taken steps to clear the air in and around its buses. The Sevier County Board of Education passed restrictions on idling earlier this month and is preparing to spend $750,000 in grant money to retrofit its buses to lower emissions.

Knoxville is at the center of nonattainment zones for both ozone and fine particle pollution. The area, which includes Sevier County, is under a federal mandate to reduce pollution levels.

The U.S. Environmental Protection Agency recommends that school districts adopt policies to restrict idling. The agency provides information on emissions-reduction technology but doesn't endorse particular devices.

Lynne Liddington, Knox County Air Quality Management director, said her office has focused more on urging the state to address idling semis and less on bus fleets.

"We really haven't actively pushed that one," Liddington said.

Liddington said school buses account for a small percentage of the area's emissions. The real benefit, she said, would come in public health.

"Even if it's not going to make a great difference when it comes to emissions, it would be healthier for the children," Liddington said. "That goes

"Even if it's
not going to
make a great
difference
when it
comes to
emissions, it
would be
healthier for
the children."

Lynne Liddington,
Knox County Air
Quality Management
director

for all the mamas and papas who pick their children up, too."

The Knox County school system doesn't have an anti-idling policy, but officials say bus operators only idle their engines for prolonged periods during the cold weather so they can keep the passenger compartments warm.

"If we turn them off, the parents say the children are cold," said Rick Grubb, Knox County Schools transportation supervisor.

Grubb said the school system monitors air quality inside school buildings and has asked bus operators not to idle their vehicles at one school where exhaust tends to blow in through the entrance.

Diesel exhaust contains significant levels of fine particles. In a report issued last week by the Southern Alliance for Clean Energy, studies in Atlanta and Ann Arbor, Mich., show that particles stream into passenger cabins quickly when buses are lined up and idling, especially when the doors are open.

The studies show that tailpipe and crankcase emission controls, coupled with the use of ultra-low-sulfur diesel fuel, virtually eliminated fine particle pollution inside the vehicles. Tailpipe controls alone aren't enough, according to the report, because up to one-fourth of the particles come from crankcase emissions.

"The results of our study clearly demonstrate that using available retrofit technology combined with ultra-low-sulfur diesel fuel dramatically improves the air quality inside school buses," concluded the report's authors, Anne R. Gilliam and Ulla-Britt Reeves.

The report found that fine particle levels inside the buses measured up to five times higher than outdoor levels, though the concentration declined as the buses proceeded on their routes.

Devices to reduce emissions can be pricey. Sevier County will spend up to $8,000 per vehicle for emissions control equipment, officials said. Using ultra-low-sulfur diesel fuel adds as much as 20 percent to fuel costs.

Liddington said Knox County officials want the state to take the lead in anti-idling legislation so that the laws are uniform across Tennessee. State environmental officials, however, are leaving the issue up to local governments.

"We support and encourage local efforts like the one in Sevier County," said Tisha Cal-abrese-Benton, a spokeswoman for the Tennessee Department of Environment and Conservation.

The $750,000 grant awarded to Sevier County Schools comes from the Clean Buses for Kids School Bus Diesel Retrofit Program. The program is funded as part of a settlement between the EPA and Toyota Motor Corp.

The money will pay for the installation of diesel particulate filters to 101 buses in its fleet and to fund the conversion to ultra-low-sulfur diesel fuel, said Karen King, finance director for Sevier County Schools.

"We had been trying to work toward doing this, but it's an expensive project," King said. "It should enable us to get our entire fleet retrofitted."

Sevier County was the only Tennessee school system to receive one of the grants under the nationwide program.

The EPA also runs a clean bus program. Last year the Chattanooga-Hamilton County Air Pollution Control Bureau received $100,000 from the EPA to outfit 83 school buses with diesel oxidation catalysts that reduce particulate matter by up to one-fourth, carbon monoxide by about 40 percent and hydrocarbon emissions by up to two-thirds.

EPA. exces-sive idling also wastes fuel, costs money and wears out engine parts.

The Sevier County policy allows idling only in the early morning and limits the duration to the manufacturer's recommendation — typically five minutes or less. Otherwise, engines are to be turned off when the buses aren't moving.

Sevier County owns its fleet of buses, while Knox County uses independent contractors. Grubb said more than 100 contractors operate buses on 375 routes throughout Knox County. Those buses cover about 22,000 miles on a typical school day, he said.

Most operators want to keep expenses down, Grubb said. That means conserving fuel by turning off the engines whenever possible.

"I can't imagine anyone would burn fuel they didn't have to," Grubb said.

Grubb said independent operators here are concerned that adding emissions control devices could reduce horsepower needed to climb steep hills and could nullify manufacturers' warranties.

Scott Barker may be reached at 865-342-6309.