 The 24-hour PSI for 16 October reached 98, just 3 points short of unhealthy.Visibility dropped to as low as 1 km in some areas, compared to the usual 20 km.The PSI on 17 October gradually increased from the moderate range in the morning to slip into the unhealthy range at 4 p.m., reaching 106, before declining back to 100 in the moderate range at 10 p.m.