A soot-caked helmet and grimy turnout gear have long been symbols of grit and experience among American firefighters. Yet exposure to contaminated equipment can increase the risk of cancer. Now, attitudes toward protective wear and other safety measures may be shifting in California firehouses.

Scientists have finally observed a fleeting chemical reaction that forms the basis of urban smog. The insight could help improve air quality forecasting models.

When cities, counties, or states provide corporations with big tax breaks to lure in factories, corporate headquarters, and other facilities, the economic benefits include more innovation outside the gates of the businesses lured into communities.