Every year, cars and trucks in the city of San Francisco spew out more than 2.5 million tons of greenhouse gases. Fortunately, the wind that tears across Twin Peaks tends to keep our air quality clean. But, as Al Gore might remind us, there's no "lockbox" for all those gases. Where do they go? VAPOR, the new exhibition-symposium at Southern Exposure, asks that very question, and provides real tools for figuring out the answers. Beatriz da Costa and Jamie Schulte of the art/tech group Preemptive Media invite you to borrow portable monitoring devices to check out the breathability of your own neighborhood air. A GPS system tells you how close you are to polluters, and the monitors beam back to Preemptive Media's Web site to create a real-time map. On March 29, Eric Paulos, senior research scientist at Intel in Berkeley, demonstrates how to analyze the information you gather in the field to create a kind of urban data landscape. Other activities throughout the next month and a half include a discussion of the nascent San Francisco Bike Share program, and a tour of artist Natalie Jeremijenko's One Tree project, in which 1,000 biological clones of the same tree were planted in various Bay Area spots. Vapor, you'll remember from grade school science, defines the state in which individual molecules are highly energized and move about freely. It's a good metaphor for citizen activism.