Indicator ST.1.f Proportion of households living within 150 meters of designated truck routes

ST.1.f Proportion of households living within 150 meters of designated truck routes

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Data Source

San Francisco Freight Traffic Route data was obtained from the San Francisco Municipal Transportation Agency, September 2009 update.

Truck route signage data obtained from the San Francisco Department of Public Works, 2009.

Residential population was obtained from Applied Geographic Solutions, Inc. Spring 2007 Update: Current Year Estimates. Methodology available at: http://www.appliedgeographic.com/library.html.

Map prepared by City and County of San Francisco, Department of Public Health, Environmental Health Section using ArcGIS software.

Table data is presented by planning neighborhood. While planning neighborhoods are larger geographic areas than census tracts, census tracts do not always lie completely within a planning neighborhood. SFDPH used ArcGIS software and a 'centroids within' methodology to convert census blocks to geographic mean center points. We then assigned census blocks to planning neighborhoods based on the spatial location of those geographic mean center points and calculated the planning neighborhood totals for the table. Detailed information regarding geographic units of analysis, their definitions, and their boundaries can be found in the HDMT at the following links:

http://www.thehdmt.org/etc/Geographic_Units_of_Analysis.September_2009.pdf

http://www.thehdmt.org/data_map_methods.php

Explanation and Limitations

In San Francisco, trucks are expected to use truck routes, arterials or freeways, except for local deliveries.  Key major and secondary arterials in the above map, created by the San Francisco Municipal Transportation Agency (SFMTA), are based on the San Francisco General Plan Transportation Element Vehicular Street Map, adopted in 1995. 

Truck route signage is one important indication of designated truck routes to truck drivers - which can help truck drivers, particularly those less familiar with local areas, stay on designated routes and off of local, residential streets (except as necessary).

Freight or truck routes are potentially significant sources of air pollution exposure. California freeway studies show about exposure levels to vehicle particulate emissions are higher adjacent to freeways and approach background levels after a distance of 500 feet.a This indicator quantifies the proportion of households in an area with a 150 meter proximity to a designated freight route.

According to the CA Air Resources Board: "Emissions are not the same as exposure. While air pollutant emissions information can serve as an indicator of local air pollution, it is the exposure to emissions that influences health effects. Exposure is the amount of pollution that someone actually breathes or otherwise ingests at different locations. Exposure varies with the distance from the source of polluton, how the emissions are released into the air and dispersed by the wind, and in what locations a person spends their time doing various activities. Exposure to air pollutants can also occur from indoor sources such as cooking, cleaning, and smoking... The importance of the exposure to health risk depends on the combination of multiple air pollutants, the relative toxicity of the pollutants, and many other factors." For more information, visit: http://www.arb.ca.gov/ch/chapis1/chapis1.htm.

The San Francisco Municipal Transportation Agency is studying the implementation of new truck parking spaces and meters. It will also continue to require off-street facilities for freight loading and service vehicles in new large non-residential developments and enforce Planning Code provisions regarding off-street freight loading.

Why is this a Community Health Indicator?

Most heavy trucks rely on diesel engines. Diesel exhaust is a known carcinogen are also major source of fine-particle pollution. Diesel exhaust can irritate the eyes, nose, throat and lungs, and it can cause coughs, headaches, light-headedness and nausea. Diesel exhaust particles made people with allergies more susceptible to the materials to which they are allergic, such as dust and pollen. Exposure to diesel exhaust also causes inflammation in the lungs, which may aggravate chronic respiratory symptoms and increase the frequency or intensity of asthma attacks. Increased asthma hospitalizations have been associated with living within 650 feet of heavy traffic and heavy truck volume.g

Epidemiologic studies have consistently found that proximity to high traffic density or flow results in reduced lung function and increased asthma hospitalizations, asthma symptoms, bronchitis symptoms, and medical visits.b Children appear to be most sensitive to adverse effects. These roadway-related respiratory effects are most likely mediated through increased exposure to vehicle emissions. California freeway studies show about exposure levels to vehicle particulate emissions are higher adjacent to freeways and approach background levels after a distance of 500 feet.a Specific epidemiologic research findings include:

  1. California Air Resources Board. Air Quality and Land Use Handbook: A Community Health Perspective. 2005. Accessed at: http://www.arb.ca.gov/ch/landuse.htm
  2. Brauer M, Hoek G, Van Vliet P, et al. Air pollution from traffic and the development of respiratory infections and asthmatic and allergic symptoms in children. American Journal of Respiratory and Critical Care Medicine. 2002;166:1092-1098.
  3. Kim JJ, Smorodinsky S, Lipsett M, Singer BC, Hodgson AT, Ostro B. Traffic-related air pollution and respiratory health: East Bay Children’s Respiratory Health Study. American Journal of Respiratory and Critical Care Medicine. 2004;170: 520-526.
  4. Brunekreef B, Janssen NA, de Hartog J, Harssema H, Knape M, van Vliet P. Air pollution from truck traffic and lung function in children living near motorways. Epidemiology. 1997;8:298-303.
  5. Venn A, Lewis SA, Cooper M, Hubbard R, Britton J. Living near a main road and the risk of wheezing illness in children. American Journal of Respiratory and Critical Care Medicine. 2001;164:2177-2180.
  6. English P, Neutra R, Scalf R, Sullivan M, Waller L, Zhu L. Examining Associations Between Childhood Asthma and Traffic Flow Using a Geographic Information System. Environmental Health Perspectives. 1999;107(9):761-767.
  7. Lin S, Munsie JP, Hwang SA, Fitzgerald E, Cayo MR. Childhood asthma hospitalization and residential exposure to state route traffic. Environ Res. 2002;88:73-81.