Tiny, airborne smoke particles blowing in from Canadian wildfires resisted dispersal from a steady, light rain across the Chicago area Wednesday, concentrating even more Thursday to reach levels unhealthy for the general public. The smoke pushed northeast Illinois into its third day in a row of bad air quality Friday and the state into its first two air pollution action days of the year. Chicago’s air quality was ranked the worst in the United States on Thursday, according to Swiss air quality technology company IQAir. At one point during the day, The Washington Post reported, the city had the second-worst...