The air on the east side of South San Francisco is not just annoying for kids with allergies and asthma, neighbors say it feels heavier, harsher and harder to escape. Community sensors, local nonprofits and public health data are all lighting up in the same direction, pointing to a long running pollution problem that residents and advocates say needs clearer answers and faster action.
According to the San Mateo Daily Journal, the census tract east of Highway 101 ranks third out of more than 1,700 Bay Area tracts on CalEnviroScreen’s pollution burden scale, and ZIP code 94080 recorded the county’s highest number of asthma hospitalizations in most years between 2013 and 2023. The outlet also reports that South San Francisco has the most hazardous waste generators in San Mateo County and that a 2017 greenhouse gas inventory flagged vehicles and nonresidential energy use as major local contributors. Data from OEHHA underlie the CalEnviroScreen ranking and show east side neighborhoods scoring high for PM2.5, cleanup sites and several other pollution indicators.
Industry Footprints And Freight Traffic Crowd The East Side
On the east side, corporate campuses and freight corridors sit cheek by jowl with homes, and those facilities have been sizable sources of energy related greenhouse gas emissions. Genentech’s 2019 sustainability report, from Genentech, shows the company’s South San Francisco campus pumping out tens of thousands of metric tons of CO2e per year in the mid 2010s, with an average of roughly 84,800 tons between 2015 and 2017, even as later years show reported reductions. City inventories that tally CO2e are crucial for climate planning, but on their own they do not tell neighbors whether the air on their block is loaded with diesel soot, industrial dust or metal rich brake and tire particles.
Community Monitors Are Filling Crucial Data Gaps
Local groups have started piecing together that neighborhood level picture on their own. Rise South City and partner organizations have rolled out PurpleAir and Clarity sensors, then built bilingual dashboards so residents can track hyperlocal PM2.5 spikes almost in real time. Those low cost monitors excel at showing fine particle surges minute by minute, but as PurpleAir explains in its technical notes, they count and size particles rather than reading their chemistry, which means they cannot tell people which toxic metals or gases might actually be in the mix.
Metal Monitors Catch What Particle Counters Miss
To fill that gap, researchers and community scientists are pairing wide networks of cheap PM sensors with new near real time metal analyzers developed by UC Davis researchers and collaborators that can see elemental composition. UC Davis teams and local partners have used these tools in nearby neighborhoods and in San Bruno to pick up elements such as aluminum, iron and manganese in the surrounding air, adding context that basic PM maps simply cannot provide. That extra layer matters because manganese compounds appear on the list of hazardous air pollutants maintained by the U.S. EPA, raising alarms about long term respiratory and neurological risks when those metals show up in neighborhood air.
Residents and advocates say the whole stack of evidence, from high CalEnviroScreen scores and a history of industrial and campus emissions to heavy traffic corridors and early metal detections, makes a strong case for more regulatory sampling and tougher controls. The city told the San Mateo Daily Journal it hopes to update its emissions inventory, and state programs are rolling out community monitoring plans; the California Air Resources Board lists approved CAMP projects that expand technical support and funding for neighborhood monitoring. For families who breathe this air every day, the request is not complicated: more chemical specific testing, faster enforcement at the biggest generators, and real steps to cut diesel and other local sources so kids are not coughing their way home from school.
