It’s the year 2060, and 75 percent of drivers in the Greater Los Angeles area have hydrogen fuel cell vehicles that emit only water vapor. Look into Shane Stephens-Romero’s crystal ball – a computer model called STREET – and find that air quality has significantly improved. Greenhouse gas emissions are more than 60 percent lower than in 2009, and levels of microscopic soot and ozone are about 15 percent and 10 percent lower, respectively. “For the first time, we can look at these future fuel scenarios and say how they’re going to impact things like ozone and particulate matter, which have severe effects on people’s lungs and quality of life,” says Stephens-Romero (pictured), a UC Irvine doctoral candidate in the Advanced Power & Energy Program. His 2060 analysis appeared online recently in Environmental Science & Technology.