| The map below
illustrates representative air pollution measurements taken at a
local scale from the city of Alameda, CA. Shown below are
concentrations of particulate matter 10 microns or smaller in diameter (PM10).
Zoom and pan around. Click on the markers to reveal the PM10 concentrations in mg/m3. Although there is not much local variability, some
locations of interest are described below. NEW: Interactive GIS Exposure Assessment Tool: Calculate exposure for your bicycle route [ here ] |
| Air pollution in the city of Alameda, CA The city of Alameda is a largely suburban island community in the East Bay, which for decades was dominated culturally, and socio-economically by its naval air base situated on the north side of the island. Since the closure of the base in 1997, property has gradually been turned over to city of Alameda. While parts of the base physically remains, the community has by and large moved on. New development, such as a 87-acre, 400+ unit planned community promises to further change the demographics of the island. Alameda has become an increasing attractive, and relatively affordable up-and-coming place in which to live, as reflected by recent awards as SF Bay Guardian's Best of the Bay 2004 neighborhoods, and as a Sweetspot in the real estate market by SF Magazine. On June 21, 2005 I took 28 2-minute PM 10 measurements at various locations on the main island and the neighboring Bay Farm Alameda community using a Met One® 531 Aerosol Particulate Profiler, a direct-reading handheld particle counter. This was a demonstration in which I familiarized myself with the unit and tested it for an actual project being carried out in San Francisco. Samples were taken on the sidewalk, at the edge of the roadway, chest-high, with the top of the unit tilted 45 degrees towards the roadway. Measurements were taken between the hours of 3 to 6pm. While air quality is generally quite uniform across Bay Farm, there exists some variability on the main island. The highest PM10 concentrations PM10= 0.026 mg/m3) were found in the Posey Tube tunnel connecting Alameda to the mainland via Oakland. The tunnel is not restricted to large diesel trucks, which are frequently present in the morning commute hours. Moreover, there is a pedestrian/bicycle lane in the tube. While those individuals who do not drive through the tunnel do not contribute to air pollution, they suffer the bulk of the exposures. The bulk of the particulate mass is larger diameter, PM7=0.018, PM10=0.026 and total suspended particulates=0.036 mg/m3. Another location of concern is the Webster Street/Santa Clara Avenue intersection, which is a major traffic corridor, with mid-level particulate concentrations. While not one of the highest concentrations, the site potentially has higher exposures, due to the outdoor farmer's market that takes place weekly each Tuesday for four hours near the location. The downtown Park Street corridor also has similar PM concentrations, and with outdoor cafes (Starbucks), may also be a site of relatively high exposure. While the sample at the South Shore Shopping Center was high, it most likely reflects adjacent dust from construction. Similarly, the measurement on Sherman Street may be influenced by spray painting of a nearby house during the time of the sampling. I did not consider variation in concentrations due to time of day. Most likely higher PM concentrations will coincide with commute hours, as traffic results in reentrainment of the particles. Moreover, inter-day variation most likely exists, particularly between weekdays and weekends. This particular study was carried out on a weekday. Clearly, PM is only one measurable aspect of air quality, which if considered more completely would take in consideration hazardous air pollutants, particularly those of which monitored by EPA. The PM monitor is currently being used to sample air quality in relationship to zoning and traffic in San Francisco to better elucidate the relationships between urban planning decisions and changing environmental health within high-density urban growth and redevelopment scenarios. For more information about the environmental quality of your neighborhood, visit Environmental Defense's Scorecard. NEW: Interactive GIS Exposure Assessment Tool: Calculate exposure for your bicycle route [ here ] [ home ] |