Galveston-Houston Association for Smog Prevention. Reducing Air Pollution From Houston-Area School Buses. March 2004.
This report overviews of emissions of school buses in Houston and estimates how this emissions will change in the future. It also aims to aid school districts in decisions in efforts to reduce emissions.
2. Where do the authors work, and what are their areas of expertise? Note any other publications by the authors with relevance to the 6Cities project.
No authors are listed, but the report is produced by the Galveston-Houston Association for Smug Prevention (GHASP). This organization was formed in 1988 by concerned citizens in a grassroots effort to prevent and eliminate smog in the Houston area. In 2008, GHASP merged with Mothers for Clean Air to better accomplish their central goal of shaping policy on air quality and environmental health issues to protect public health. The new organization was named Air Alliance Houston. For more information, see my organization profile on Air Alliance Houston.
A paragraph in the acknowledgements states: "Finally, GHASP acknowledges the financial support of its contributors, and the two internship programs that made this project possible. Rachel Krause was supported by the Texas Public Interest Research Group Fellowship and Dustin Rynders was supported by the ECO/EPA Community Intern Program, sponsored by the US Environmental Protection Agency Office of Environmental Justice." This implies that Krause and Rynders had a large part in the project, but it fails to go into detail and they are not mentioned in any other part of the report.
3. What are the main findings or arguments presented in the article or report?
Every school day, buses emit nearly 6 tons of NOx in the Houston region.
Better technology and more stringent government regulations have led to improved NOx emissions in newer model year buses.
The 5 largest school districts emit over half the NOx emissions from buses in the entire region.
Without even taking further actions, the area's school buses are predicted to emit 20% less NOx by 2007.
The replacement of older buses that produce more pollution will compensate for the anticipated growth of enrollment, which will cause demand for more buses.
The state has required that diesel in the area meets the Texas Low Emission Diesel (TxLED) standard by 2005, which will lower NOx emissions by 5.7%
To go beyond this 20% reduction, schools must take more aggressive actions.
School buses in the Houston region emit about 381 pounds of fine particulate matter. While Houston is in compliance for the PM standard (just barely below it), this still poses a dangerous threat to health. (further discussed in Question 7)
Districts must make replacing buses built before 1990 a high priority in order to reduce emissions (further discussed in Question 4).
Diesel idling is arguably the largest and most preventable health hazard related to school buses. State law places some restrictions on idling, but districts need more comprehensive idling policies, and new mechanisms for enforcement must be created.
4. Describe at least three ways that the argument is supported.
The report establishes the necessity of implementing new strategies to reduce emissions of buses, especially Nitrogen Oxides, which contribute to the formation of ground-level ozone, Houston's number one air pollution concern.
Houston air does not meet the federal standard for ground-level ozone set by the Clean Air Act.
The State Implementation Plan (SIP) calls for the significant reduction of NOx emissions (60% overall reductions) from nearly all pollution sources in the Houston area. It specifically calls for a 55% reduction from heavy-duty mobile sources.
If the federal standard for ozone is not met by 2007, the EPA is obligated to impose sanctions, including taking away federal highway dollars.
The report creates a comprehensive table for EPA Engine Certification Standards for Heavy-Duty Vehicles to justify suggestions on what model buses to replace. One quarter of Houston's bus fleet was built before 1990, and prior to this year new buses were allowed to 6 times more soot and almost 3 times more NOx than the average diesel bus at the time of the study in 2004. The report uses this to support their claim that buses built prior to 1990 need to be replaced urgently. Furthermore, to prove that buying the newest available buses possible will make a significant difference, the report points to the fact that buses under the 2004 standard have half the NOx emissions of buses manufactured the previous year, and 2007 standards will require new buses to produce one tenth the NOx and PM emissions of the 2004 buses.
To prove the feasibility of the suggested measures to reduce emissions, cost-effectiveness is determined for the solutions and information is provided on how a school can fund emission reduction measures. However, this process also addresses the complexity of decisions that affect emissions. Based on the cost calculations, there is no one solution that stands out as the best by far. Furthermore, while buses are an important point of intervention for the health aspect in children, they are actually not a cost effective solution to reducing NOx emissions compared to reductions from other sources in the Houston area. This is because buses are in use less of the time, while high-use freight equipment could be in use everyday for 10 hours a day.
To help schools pay for emission reduction actions, the report overviews both the Adopt-a-Bus Program and the Clean School Buses USA (discussed further in Question 10).
5. What three (or more) quotes capture the message of the article or report?
"Houston-Galveston area school districts operate approximately 7,500 school buses to offer the region’s nearly one million students a safe and reliable ride to and from school. Because the region’s school districts typically use buses for about twenty years, only about a third of the region’s school buses meet recent federal standards for pollution control. New school buses are much cleaner than those offered in years past because of technology improvements spurred by more stringent government standards."
"If school districts are to go beyond a 20% reduction in NOx emissions, they will need to consider more aggressive actions. For instance, to achieve a 50% reduction in NOx emissions, the average NOx emission rate from school buses would need to drop to about 5 grams per mile, considerably below the rate for the cleanest district in the region."
"While diesel PM from school buses is a significant regional environmental problem, a greater concern is the micro-environment within and near school buses that children are exposed to every day they ride a school bus. Especially when buses idle at schools, traffic lights, and bus stops, fine PM levels inside and near school buses rises dramatically. Students inside, boarding or walking near a school bus are potentially exposed to very high levels of fine PM pollution from the diesel exhaust. While school buses are a safer transportation choice than many alternatives, the current fleet of school buses in use places children, especially those with respiratory disease, at an unnecessary health risk, and places others exposed to the same emissions in traffic, neighborhoods or the schoolyard at risk as well."
6. What were the methods, tools and/or data used to produce the claims or arguments made in the article or report?
GHASP contacted school districts directly to request an inventory including bus model year, engine size, engine manufacturer, capacity, fuel type, and annual miles traveled. They also asked each district for total fleet miles and students served and information about idling policies, fueling stations, and purchasing practices.
36 school districts provided inventory and information, while 13 did not. Weighting it using each schools enrollment, this accounted for 88.5% of the region.
GHASP used the provided data, along with student enrollment data from the Department of Education’s National Center for Education Statistics, to model mileage, bus purchasing, and bus replacement.
Only 7 school districts provided specific mileage data by model year. This is problematic for modeling because older buses are often driven fewer miles than newer buses. To adjust for this, estimate the mileage traveled by each bus in the region, a standard distribution of miles by model year was derived from the seven-district sample, and this distribution was then adjusted for each district by its total fleet mileage.
Bus need for each district was determined using the bus per student ratio. Growing districts were assumed to purchase new buses to meet need, and districts with decreasing enrollment were assumed to retire buses as necessary. To determine the rate of growth, linear regression was used to forecast student enrollment for the 2003 to 2007 school years.
Emission factors were used from the Houston-Galveston Area Council’s (HGAC’s) heavy-duty emissions calculator. The calculator provides emissions factors (in grams per mile) based on class, year, and fuel type. When school districts did not provide information on class, it was approximated based on bus capacity. HGAC emission factors were available for NOx, PM, and VOCs for diesel engines, and NOx emission factors were also used for gas-powered buses.
This report mentions that there is little information on PM emissions from heavy-duty gasoline engines, which makes determining the PM emissions of a bus' engine difficult. The EPA assumes them to be small, because there has not been an imposed regulation on PM emissions for heavy-duty gasoline engines. So, the report utilized the state of California's EMFAC 2000 model was used to estimate PM from gasoline school buses, which assumes gasoline-powered heavy-duty trucks of all model years will emit 0.054 grams per mile, with no deterioration over time. The report address that this could underestimate emissions for 2 reasons. Firstly, the testing was performed on newer trucks, which generally have lower emissions than the older vehicles because of engine improvements over time. Secondly, the data for particulate emissions in the model was based on data for light-duty trucks, and it is unclear how closely the emissions profile for medium heavy-duty vehicles such as school buses would compare.
Emission factors for future model year buses were estimated using federal emission standards. EPA's plan to phase-in the new standards requires that 50% of the engines sold in 2007 meet the new 2007 standard. To account for this, GHASP used an average of the 2004 and
2007 certification standards to calculate 2007 emission factors.
For cost analysis, the calculations from the Texas Emission Reduction Plan (TERP) were used. TERP estimated that the cost effectiveness of a project is determined by dividing the total annualized cost by the total annual NOx reduction. The price of a new diesel bus ($65,000) was used for the early replacement strategy, because it was more cost effective than an alternative fuel bus.New buses purchased in 2007 were assumed to cost $2,750 more than 2004 buses, based off an estimate by the EPA for their proposal of the new standards in 2000.
7. How (if at all) are health disparities or other equity issues addressed in the article or report?
The report mentions that PM emissions are proven to be associated with asthma, reduced lung function, and acute respiratory illness. Buses increase PM emissions in areas that are near children. This is addressed as a health disparity in the report, as children are more susceptible to these health risks since they inhale 50% more air per pound of body weight than adults.
8. Where has this article or report been referenced or discussed? (In some journals, you can see this in a sidebar.)
This report is referenced on Air Alliance Houston's website. Air Alliance Houston makes available all reports done by GHASP, their predecessor organization, on their website for the public to utilize. Source
The report is referenced by a study conducted by the Texas Transportation Institute in 2005 titled Reducing School Bus Emissions in Texas. TTI uses the data obtained from GHASP, and supplements it personal interviews and written questionnaires emailed and faxed to the selected school districts, especially for districts that did not provide information to GHASP. This would serve as an interesting comparison between reports from a citizen lead group and a research agency with extensive resources on the same topic concerning transportation and air pollution. It also demonstrates that GHASP's efforts to bring the issue to attention were successful. Source
9. Can you learn anything from the article or report’s bibliography that tells us something about how the article or report was produced?
In the acknowledgements, GHASP thanks the public agencies that made a special effort to assist with the project, including the US Environmental Protection Agency Region VI, EPA’s Clean School Bus USA program, EPA’s voluntary diesel retrofit program, and the EPA’s verification program. Furthermore, one of the interns involved in the project was sponsored by the the US Environmental Protection Agency Office of Environmental Justice. This indicates a strong involvement of the EPA, likely hoping for the study to produce data and information that will support the federal bus programs.
10. What three points, details or references from the text did you follow up on to advance your understanding of how air pollution science has been produced and used in governance and education in different settings?
A Houston Chronicle in 2003 discusses the Adopt-a-School-Bus program mentioned in the report. The article is titled "HSD getting less-polluting school buses." It focuses on the announcement by environmental and educational officials of the new Adopt-a-School-Bus program. The program aims to replace 500 of the region's oldest diesel buses that emit the most pollutants. New buses, which will be powered by cleaner technologies such as natural gas and low-sulfur diesel, will be funded by a combination of private and public sources. In return for funding a bus, sponsors can have their logo put on the side of the bus. The article also references the GHASP bus report, but this article was published a year before the study, so this implies that GHASP had been in communication with the paper before releasing the study publicly. Source
The report discusses the Clean School Buses USA which was funded through a designation of $5 million as a budget for the EPA program through congress in 2003. The program aims to assist schools in replacing their bus fleets. The Texas State Energy Office received a grant, and will use will use $300,000 in the Houston area to install particulate traps on 22 buses and modify 135 dieselpowered buses to take full advantage of the TxLED fuel. The report also mentions that $5 million dollars has been allocated in the 2004 budget as well. I followed up on the current funding, which is now up to $7 million per year (source). This indicates a 40% increase in funding over the past decade, demonstrating an increasing trend in attention and concern for buses as a source of pollution.
Furthermore, both these major programs began in 2003, followed by the GHASP report in 2004, and TTI study in 2005. This helps flesh out the timeline for air quality and transportation, and marks when bus emissions became a major concern.
11. Does the article provide information or perspective on any of the thematics already identified as important for the 6Cities project?
Scientific capacity to link air pollution to health impacts has grown dramatically in recent years, although much of this research has yet to be translated into policy.
References a 1993 report published in the New England Journal of Medicine that studied over 8.000 adults in 6 different cities. The death rate in the most polluted city was 26% higher than in the least polluted city, and through the controlling of known variables, a significant association was established between. PM matter and deaths from cardiopulmonary disease and lung cancer. source
All 6 cities were located in the US, which serves as a more unique example. Many studies compare the US to China or India and US citizens are often more okay with disparities between us and other countries, but it gains more momentum when it is disparities as significant as 26% within our own country.
Increasingly, researchers themselves are calling for specific policies and interventions.
For this study, only 7 of the districts (out of 36 school districts that provided information) reported having an idling policy, and only a few of those reported having any sort of mechanism of enforcement. The report made the following recommendations:
Morning warm-ups should be limited to the time recommended by the manufacturer, which is usually 3 to 5 minutes.
Zero idling should be allowed for buses at drop off and loading areas. Often, buses all wait in one location while idling. Many stationary buses idling together creates a very high PM concentration in the area, posing a health risk to both the students and drivers. The report instead recommends providing a climate-controlled space inside the school for the drivers to wait.
Fleet managers should be required to ensure that the engine does not need to be running to power flashing lights on the bus. Buses that do not meet this requirement could have the circuit configuration modified to allow the lights to power without the engine.
Fleet managers should find modes of communication to justify the policies to the drivers (newsletters, meetings, etc). Frequently reminding them the intent of the policies, which is to reduce health risk, will motivate them to follow the rules.
Enforcement measures most be created, otherwise the policies are essentially useless. (However, the report did not suggest any strategies for enforcement.)
2. Where do the authors work, and what are their areas of expertise? Note any other publications by the authors with relevance to the 6Cities project.
3. What are the main findings or arguments presented in the article or report?
4. Describe at least three ways that the argument is supported.
5. What three (or more) quotes capture the message of the article or report?
6. What were the methods, tools and/or data used to produce the claims or arguments made in the article or report?
2007 certification standards to calculate 2007 emission factors.
7. How (if at all) are health disparities or other equity issues addressed in the article or report?
8. Where has this article or report been referenced or discussed? (In some journals, you can see this in a sidebar.)
9. Can you learn anything from the article or report’s bibliography that tells us something about how the article or report was produced?
10. What three points, details or references from the text did you follow up on to advance your understanding of how air pollution science has been produced and used in governance and education in different settings?
11. Does the article provide information or perspective on any of the thematics already identified as important for the 6Cities project?