Criss-crossed by major roads, including California's Route 99 and Route 140, which takes many travelers to Yosemite National Park, Merced has long struggled with ozone and emission-related pollution.
In fac,t, some 80% of the area's harmful pollutants can be traced to transportation sources, said Bonnie Holmes-Gen, senior director for policy and advocacy for the American Lung Association in California. However, Merced is making progress in reducing its ozone levels, with the pollutant hitting it lowest level in 14 years, she said.
Another issue facing the town is its proximity to San Francisco and Oakland. Jared Blumenfeld,of the EPA, estimates that as much as a quarter of the pollutants in Merced drift in from those metro areas.
