Health Effects Task Force
The Health Effects Task Force (HETF) is a group of air quality and health experts who for over a decade have volunteered to leverage their skills and expertise to further locally based studies on the health impacts of air pollution in Sacramento and the Central Valley of California. This is an area with known and serious air pollution problems that differ significantly in type from other extensively studied areas in California and the nation.
HETF has been chaired since its inception by Jananne Sharpless, past chairwoman of the California Air Resources Board, with members drawn from organizations such as the Cal EPA/ARB, Kaiser Permanente, California Office of Environmental Health Hazard Assessment, University of California, Davis, Sacramento County Health Department, and local research companies, among others.
Local air districts have funded the work of HETF with modest grants for over ten years with results only achievable because of the dedication of this extraordinary group of volunteers.
Eight studies specific to this region have been completed identifying:
• How strategically placed vegetation downwind of busy roadways can remove ultrafine particulates from the air, thereby protecting the health of residents,
• Effects of air pollution on mortality rates from ischemic heart disease and stroke in the Central Valley,
• Particulate air pollution and rate of hospitalizations;
• Increased hospitalizations and emergency room visits of MediCal youth with asthma during high ozone days; and
• Three studies on exposure to ultrafine particulates across Sacramento and at a school site directly downwind of a densely trafficked urban corridor.
Other studies in progress include: a ten year study looking at air pollution effects on the elderly; high school students conducting on campus indoor and outdoor air quality assessments at regional high school sites; a study on the health protection effect of vegetation and downwind barriers on very fine and ultrafine particulates from freeways; and a one year comparative study of data captured by the Cahill 8 drum sampler and the California Air Resources Board monitor at the 13th and T Streets site in Sacramento.
Health Effects Task Force Studies 1995-2009
We have completed work on eight local studies on air pollution in collaboration with UC Davis, Kaiser Permanente, California Department of Health Services, California Air Resources Board (CARB), and California Office of Environmental Health Hazard Assessment, with funding from Sacramento Metropolitan Air Quality Management District and Yolo-Solano Air Quality Management District.
May 2009 Thomas A. Cahill and David E. Barnes, UC Davis DELTA Group:
Comparison of Fine Mass, UC Davis DRUM versus FRM, at the ARB 13 th and T Street Site
This one year side by side monitoring study, sanctioned by the California Air Resources Board at its 13th and T Street site, compares mass data collected by the U C Davis rotating drum impactor (8 DRUM) with ARB’s standard mass monitoring measurements. The study showed that the 8 DRUM monitor proved to be a cost effective way to obtain important additional data for health and regulatory needs while being accurately comparable to the ARB’s mass measurements currently required by law. In particular, this study introduces vital new information about ultrafine particulate matter which studies now show is capable of deep lung deposition, and heart and brain impacts.
April 2008 T. A. Cahill PhD, UC Davis:
Removal Rates of Particulate Matter onto Vegetation as a Function of Particle Size
Conducted at the University of California, Davis, this wind tunnel study showed that all forms of evergreen vegetation were able to remove 30% to 80% of very fine particles at wind velocities below roughly two miles per hour during the 2 to 4 seconds in which the particles were within the vegetation chamber. Redwood and deodar were about twice as effective as live oak. The success of this study has led to one to begin January 2009 that will compare protective qualities of evergreen vegetation downwind and adjacent to Highway I-5 in Sacramento as compared to unprotected sites also downwind of I-5. Click here to read a one page summary of the report.
2007 T.A. Cahill, PhD, UC Davis and T.M Cahill, ASU:
Air Quality at Roseville Railyard Poses Cancer Risk : Recent Study by Health Effects Task Force Also Outlines Multiple Solutions
This study was conducted in collaboration with the Placer County Air Pollution Control District (PCAPCD) and its Roseville Railyard Aerosol Monitoring Project (RRAMP). The study report consists of seven components all of which bear on monitoring emissions from the Railyard in Roseville. Some components were funded by EPA Region IX in a grant to PCAPCD and some were collected by Dr. Cahill as a volunteer with Breathe California of Sacramento-Emigrant Trails (BCSET) and the Health Effects Task Force (HETF). This study is the first of its kind to analyze the chemical content of the highly toxic ultrafine particulates in locomotive diesel at the railyard. A key study finding revealed that the locomotive diesel exhaust from the Roseville Railyard is about 5.5.times richer in the most carcinogenic components of diesel exhaust (benzo[a]pyrene, among others) than is the exhaust from diesel trucks. A chapter of this report is dedicated to recommendations for mitigation of emissions at the Roseville Railyard.
Press Release - Air Quality at Roseville Rail Yard Poses Cancer Risk: Recent Study by Health Effects Task Force Also Outlines Multiple Solutions
Final Report - Mass, Organic, and Elemental Aerosols by size, time, and composition at the Union Pacific Rail Road’s Roseville Railyard
There has been substantial media coverage of the health impacts of exposure to diesel pollution in and around the Roseville Rail Yards. It is important, however, to appreciate that, as stated in the Sacramento Bee article, the predicted increase in lifetime cancer rate from the Air Resource’s Boards 2004 analysis was 1 part on 1,000 or less for the vast majority of local residents. Other impacts, such as increases in asthma, are harder to predict but can certainly occur.
Nevertheless, there are actions you can take to better protect your health:
Install filters in your heating and cooling systems – passive electrostatic filters appear to be a good choice;
Be extra vigilant in keeping your filters clean and change them more frequently;
Avoid tracking dirt inside and open windows away from the diesel pollution source;
Minimize your time spent outdoors in situations in which you observe diesel smoke is present,
Next spring, plant a row of vegetation with thick foliage as a barrier which may be effective to absorb diesel smoke. Good evergreen choices might be deodars, cedars, redwoods, and interior live oaks. More studies are being done on the most effective vegetation barriers and results should be available soon.
Other mitigations are being implemented within the rail yard itself by Union Pacific Rail Road as per an agreement with Placer County and other agencies, and the report on their progress is currently scheduled for release next Spring.
To read the complete study, click here.
2006 T.A. Cahill, PhD, UC Davis:
Vehicular Particulate Exposures and Potential Mitigations Downwind of Watt Avenue, Sacramento, California
This third and final phase of a series of studies conducted by Dr. Cahill for Breathe California of Sacramento-Emigrant Trails focused on air quality impacts from traffic on Watt Avenue which confirmed previous findings that very fine and ultrafine particulates substantially impacted Arden Middle School immediately downwind of Watt Avenue at Arden Way. A new section in this report addresses mitigation opportunities for those who reside downwind of heavily trafficked urban corridors such as Watt Avenue. This report also emphasizes that although the California Air Resources Board has declared diesel particulates toxic to human health (California Almanac 2006), no health protection standards have been established by the California Air Resources Board or the Environmental Protection Agency for the very fine and ultrafine particulates found in diesel exhaust. This study received guidance and support from Arden Middle School and San Juan Unified School District personnel and county departments.
2005 T.A. Cahill, PhD, UC Davis:
Sacramento/Interstate 5 Transect Study, Phase II, Winter Months
This second phase examined the impacts of secondary roadways carrying predominantly car traffic. On Watt Avenue, diesel trucks, although they represented only about 1.5 percent of all vehicles, contributed about 1/3 of all the very fine and ultrafine particulates, while cars contributed 2/3 of the very fine and ultrafine particulates, which substantially impacted Arden Middle School.
2003 T. A. Cahill, PhD, UC Davis:
Sacramento/Interstate 5 Aerosol Transect Study
This study measured air pollution levels at nine sites upwind and downwind of Highway I-5 and east to the foothills. The level of diesel/smoking gasoline vehicle impacts was larger at Arden Middle School directly downwind of Watt Avenue than at the Crocker Art Museum directly downwind of Highway I-5, despite lower traffic flows on Watt Avenue. Very fine particulates traveled well away from freeways and filled large areas of downtown Sacramento.
2003 California Air Resources Board:
Short Term Study of Outdoor Air Quality at Two Sacramento Schools on Watt Avenue
This limited study provided some insight into the air quality of the two schools, Arden Middle School and Frederick C. Joyce Elementary, but showed that the overall Sacramento region had a stronger influence over the air quality of the schools than the local sources of air pollution. Diesel particulate was not measured as part of this study because no methods to measure diesel particulate were available to CARB at the time the study was conducted.
2003 Study in collaboration with Michael Lipsett, MD, OEHHA on MediCal youth with asthma in the Sacramento Region:
Air Pollution and Exacerbation of Pediatric Asthma in Sacramento
Specific to the Sacramento Region, this study demonstrated a link between SMOG and childhood asthma attacks resulting in hospitalizations and emergency room visits. This study has not been released for publication.
2002 Study in collaboration with Steve Van Den Eeden, PhD, Kaiser Permanente:
“Particulate Air Pollution and Morbidity in the California Central Valley”
This study found strong and consistent air pollution effects between particulate matter and acute and chronic respiratory hospitalizations among Kaiser Permanente members, 60 percent of whom lived in the Sacramento Region.
1998 Study in collaboration with T.A.Cahill, PhD, UC Davis:
“Comparison of Cardiac and Stroke Mortality to Carbon Monoxide, Ozone, and Particulate Air Pollution Concentrations in the Sacramento Valley Region”
This study compared CA Dept. of Health Services mortality data to CARB air pollution data, suggesting a statistically strong link between PM 10 and increased mortality from ischemic heart disease, with weaker evidence for heart attacks and strokes and ozone air pollution.
To receive any additional information regarding these studies and/or the Health Effects Task Force, please contact Betty at ext. 211 or email