More worrisome to them is the prospect of breathing in pollutants such as nitrous oxide, which mixes with oxygen in the atmosphere to produce ozone.
"It's the worst place you'd ever want a power plant," said Elizabeth Cord, president of the Santa Teresa Citizen Action Group, sipping coffee at a Starbucks in a pastel-colored mall on a recent sunny day. With her two home-schooled children in tow, she pulled out a blue folder bursting with ammunition: pollution charts, letters to the editor, maps showing plants slated for remote parts of California.
"We're not saying it should be built in someone else's back yard," Cord said. "There are plenty of places in the state without any back yards."
Cisco's project, on the other hand, makes sense to her for many reasons. Not least is that Santa Teresa residents could work there, meaning fewer cars would clog already congested freeways.
Cisco, for its part, opposes the plant for "health and safety reasons." The company - which would keep its sprawling operation in North San Jose, the heart of the city's high-tech district - plans to put a large day-care center on site. "We don't think it's a good idea to put 800 kids next to a power plant," said spokesman Steve Langdon.
Between the proposed plant on Tulare Hill, and Cisco's planned 6.5 million-square-foot expansion, the look of South San Jose would be transformed. Its agricultural character has waned since the city designated the valley floor for campus-style developments years ago. Some corn still grows on part of the Cisco property, and a few fruit trees stand along Monterey Road.
But it's hardly pristine anymore, with transmission lines visible all around.
In fact, Calpine likes its site because a substation already sits across the road, eliminating the need to move the power over miles of new wires and minimizing the weakening of current that occurs when electricity moves great distances. A natural gas pipeline is also less than a mile away.
Calpine's Poelle asserted that the traffic generated by Cisco's expansion would do more harm to the environment than the plant's emissions. She added: "When [Cisco officials] say it's going to waft over and hurt the children, they're making that up."
Kurt Newick, a member of the local Sierra Club chapter, once had grave doubts about the power plant. Then he did his own analysis and found that Cisco would foul the air more than the plant would. At the same, he said, the plant would reduce dependence on dirty coal-burning plants elsewhere.
Cord and her fellow residents, he said bluntly, "are selfish." "They're barking up the wrong tree," he added. "Because if you're really serious about air pollution, you've got to clean up the cars."