In early November, gale-force winds whipped a brush fire into an inferno that nearly consumed the town of Paradise, California, and killed at least 86 people. By the second morning, I could smell the fire from one foot outside my door in Berkeley, some 130 miles from the flames. Within a week, my eyes and throat stung even when I was indoors. Air quality maps warned that the soot-filled air blanketing the Bay Area had reached “very unhealthy” levels. For days, nearly everyone wore masks as they walked their dogs, rode the train, and carried out errands. Most of those...