Singapore's air quality has slipped back into the unhealthy range after a short spell of cleaner air early on October 23. The morning lull gave residents a brief window to be outside without masks. By later in the day the readings had climbed again, pushing the pollutant index past the line that marks unhealthy air. The haze has moved over the island in waves, and each rise keeps people watching the numbers. Anyone with outdoor work or plans has been adjusting schedules as conditions swing from hour to hour. Officials keep posting regular updates so residents can judge when it is safe to venture out. For now, the smoky air that has hung over the region for weeks shows no sign of clearing for good.