E: info@barhii.org | T: 510-210-8065

Air Contamination

Peak concentrations of particulate matter


Poor air quality can contribute to adverse health outcomes. Exposure to higher levels of air pollution may increase the risk of developing health conditions such as heart disease, cancer, and respiratory illness such as asthma. Poor air quality can also exacerbate pre-existing health conditions in already vulnerable groups, such as asthma symptoms in children. Air pollution often results from high levels of ozone and particulate matter released into the environment from sources such as factories or cars. Air pollution is not equally distributed in communities. The burden of breathing in unhealthy air is often disproportionately borne by low income and communities of color, many of which are situated closer to busy highways, ports, factories, and other pollution sources.

Clean air is a fundamental building block of human health. Air pollution from fixed and mobile sources (e.g., factories and cars, respectively) is a complex mixture of gases, fumes, and particles released into the atmosphere from the combustion of fossil fuels and evaporation of solvents. Ozone that forms at the ground level and fine particulate matter (PM) are two indicators of air pollution that are linked to short- and long-term adverse health effects. PM that has an aerodynamic diameter of 2.5 microns or less is called PM2.5 and is capable of reaching deep into the lungs causing a host of diseases including lung cancer, heart disease, respiratory disease, and acute respiratory infections, particularly in children. In California, the Air Resources Board estimated that, given the PM2.5 levels between 2004 and 2006, over 9,300 deaths could be prevented each year if California met its current statewide PM2.5 standard of 12 µg/m3.

Based on numerous community-based epidemiologic studies, both short-term and long-term exposures to PM2.5 increase the risk of cardiovascular disease and mortality, and are linked to adverse respiratory outcomes such as chronic obstructive lung disease, hospital and emergency department admissions for asthma, increased respiratory symptoms, altered pulmonary function, and pulmonary inflammation among asthmatic children. While not definitive, evidence is accumulating for PM2.5 effects on low birth weight and infant mortality, especially due to respiratory causes during the post-neonatal period.


Note to LHDs in California: The California Department of Public Health’s Healthy Community Indicators (HCI) project has already collected, cleaned, and compiled these data for California from the California Air Resources Board, which can be found at http://www.cdph.ca.gov/programs/Pages/HealthyCommunityIndicators.aspx. Appendix D explains how to download and filter these data. Counties outside of California may need to contact their state air quality resource board or equivalent agency.

The map below shows the annual mean ambient concentration of fine particulate matter for zip codes in the San Francisco Bay Area. Bay Area Regional Health Inequities Initiative (BARHII) recommends that analysis of this indicator be at the zip code level, which is the smallest level of geography available.

Limitations of the Data

Geographic coverage was not complete because of the limited number and geographic extent of air quality monitoring stations. The uncertainty of the interpolated values increases with distance from the nearest monitor. According to the Air Resources Board, values for areas greater than 50 km from the nearest monitor are very imprecise, and should be regarded as speculative. They are included for the sake of completeness, but should not be relied upon. Even within populated areas, monitoring stations are often located in areas that cannot detect highly localized areas of pollution that significant numbers or sensitive subgroups (e.g., daycare centers, schools, or hospitals) in the population may encounter. Data were not available to present standard errors.

Figure 36: Annual Mean Ambient Concentration of Fine Particulate Matter (PM2.5),
BARHII Region, 2007-2009.


Providing Input into the Development of the Bay Area Sustainable Communities Strategy Planning Process
Contra Costa Health Services

Contra Costa Health Serves is a member of the Bay Area Ditching Dirty Diesel Collaborative, a regional collaborative of grassroots groups, non-governmental organizations and LHDs. The objective of the collaborative is to reduce the burden of diesel pollution on health, especially in low-income, minority communities that are disproportionately affected by diesel pollution. One of the activities of the collaborative over the last five years has been to influence the Sustainable Communities Strategy (SCS) process under SB375 to better address the health impacts of diesel pollution, especially the impacts on the occupants of new housing and other facilities (e.g., schools, senior centers, medical facilities) that will be cited in close proximity to sources of diesel pollution as a result of the emphasis on in-fill in the SCS.

As a way to support this advocacy effort, one of the members of the collaborative, the Pacific Institute, prepared a report, At a Crossroads in Our Region’s Health: Freight Transport and the Future of Community Health in the San Francisco Bay Area (http://pacinst.org/publication/at-a-crossroads-in-our-regions-health-freight-transport-and-the-future-of-community-health-in-the-san-francisco-bay-area-2/). Contra Costa Health Services participated extensively in the development of this report. The report detailed where new development could occur within areas designated by local jurisdictions as priority development areas for growth that wasn’t exposed to highest levels of risk from diesel sources. This information then served as the basis for policy recommendations for directing growth in a way that would minimize the impact to public health while still meeting the development goals of the SCS.

Contra Costa Health Services continues to be in an active participant in Ditching Dirty Diesel’s follow-up effort to the report called the Pollution Free Housing for All Campaign, which will not only will try to help establish policies and practices for building new housing that is protected from the highest levels of diesel pollution, but will address how to do this without impeding the development of affordable housing. This effort will also address how to lessen the impact of diesel pollution on existing housing without exacerbating the negative impacts of gentrification.

Promoting Active Transportation
Santa Clara County Public Health Department

Santa Clara County is a large county with over 1.8 million residents with a very diverse population. Additionally, many people commute to Santa Clara County for work; the county is home to several large technology companies that comprise what is known as Silicon Valley. With a large population of residents and workers, in addition to the county’s geographic location, Santa Clara County often experiences days with poor air quality. In 2014, the county received a “D” grade for high ozone pollution days and for 24-hour particle pollution in the State of the Air report published annually by the American Lung Association.

In efforts to promote active transportation, the Santa Clara County Public Health Department partnered with cities on several strategies through Communities Putting Prevention to Work (CPPW). Active transportation strategies in partner cities included zoning studies, alternative commute recommendations, bike share program outreach, complete streets (streets designed to provide safe access to all users, regardless of age or transportation mode), and other strategies.

Bay Area Bike Share, one example of a partnership with cities and local agencies to promote active transportation, offers the public access to shared bicycles in select locations in the San Francisco Bay Area. The Santa Clara County Public Health Department provided assistance to the City of San Jose, which presently offers 150 bicycles in 15 locations in the downtown area. Two other cities in the county participate in Bay Area Bike Share—Mountain View and Palo Alto.

Also as part of CPPW, four school districts adopted Safe Routes to School policies. Safe Routes to Schools promotes biking and walking among children as a way to get to and from school. Safe Routes to Schools also emphasizes safety by partnering with cities and schools to promote safe passages for children to get to school, as well as safety training, such correct helmet usage. The adopted polices reach 45,000 students in 76 schools in the county.

As people walk and bike more, they become less reliant on driving to meet their transportation needs. A reduction in driving means reduced vehicle emissions, a contributing factor to pollution and poor air quality. Residents that live alongside freeways, such as lower-income families living in multi-unit housing, may be particularly affected by poor air quality due to motor vehicle emissions and so may especially benefit from countywide active transportation policies and programs.

Health Impact Assessment on Traffic Congestion Pricing
San Francisco County Department of Public Health

The San Francisco Department of Public Health’s (SFDPH) Program on Health, Equity and Sustainability received funding from the Robert Wood Johnson Foundation’s Active Living Research program to conduct a health impact assessment (HIA) of a congestion-pricing policy under study in San Francisco. Specifically, the San Francisco County Transportation Authority (SFCTA) was studying a potential program that would charge $3 during rush hours to travel into or out of the congested northeast quadrant of San Francisco. This road-pricing fee would fund public transit, road maintenance, and bicycle and pedestrian street improvements.

In the Summer of 2011, SFPDH completed the HIA and found that with the potential future implementation of congestion pricing, San Franciscans could see significant health-related improvements relative to a future without road pricing—including fewer deaths due to air pollution, more cycling and walking and associated health benefits, and fewer pedestrian and cyclist injuries. The HIA did not find evidence of inequitable health effects on low-income, elderly, or young populations.

The HIA also estimated that the health-related economic costs of today’s transportation system are very high—as much as $1.12 billion a year. Congestion pricing could generate significant economic value by reducing transportation-related adverse health effects and increasing walking and biking. The HIA also made recommendations that specifically target enhancing health benefits of the policy, including increasing congestion pricing fees where they can reduce health risks (e.g., on spare-the-air days) and investing in targeted infrastructure to reduce pedestrian and cyclist injury and increase walking and biking for transportation. For more information see http://www.sfhealthequity.org/elements/transportation/21-elements/transportation/116-road-pricing-health-impact-assessment-hia.


American Lung Associate. 2014. Disparities in the Impact of Air Pollution. http://www.lung.org/our-initiatives/healthy-air/outdoor/air-pollution/disparities.html. Accessed January 2014.

Drechsler D, Garcia C, Tran H, Mehadi A, Nystrom M, Propper R, et al. 2005. Review of the California Ambient Air Quality Standard For Ozone. Vol 4. Table B-5: California Annual Health Impacts of Current Ozone Concentrations Compared to the State 8-hour Ozone Standard of 0.070 ppm. Sacramento, CA: California Environmental Protection Agency, Air Resources Board. http://www.arb.ca.gov/carbis/research/aaqs/ozone-rs/rev-staff/vol4.pdf. Accessed January 2014.

Garzón C, Ditching Dirty Diesel Collaborative Freight Transport Committee, et al. 2011. At a Crossroads in Our Region’s Health: Freight Transport and the Future of Community Health in the San Francisco Bay Area. http://pacinst.org/publication/at-a-crossroads-in-our-regions-health-freight-transport-and-the-future-of-community-health-in-the-san-francisco-bay-area-2/. Accessed June 2014.

Particulate Matter Integrated Science Assessment Project Team. 2009. Integrated Science Assessment for Particulate Matter. Research Triangle Park, NC: U.S. Environmental Protection Agency. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=216546#Download. Accessed January 2014.

San Francisco Department of Public Health Program on Health, Equity, and Sustainability. 2014. Road Pricing Health Impact Assessment (HIA): How Could Road Pricing Impact on Our Health? http://www.sfhealthequity.org/elements/transportation/21-elements/transportation/116-road-pricing-health-impact-assessment-hia. Accessed June 2014.

Tran HT, Alvarado A, Garcia C, Motallebi N, Miyasato L, Vance W. 2009. Methodology for Estimating Premature Deaths Associated with Long-term Exposures to Fine Airborne Particulate Matter in California (Draft: Staff Report). Sacramento, CA: California Air Resources Board. http://www.arb.ca.gov/research/health/pm-mort/pm-mort_final.pdf. Accessed August 2013.