2025-01-17 00:00:00 Haze is traditionally an atmospheric phenomenon where dust, smoke and other dry particles obscure the clarity of the sky. Though not a common occurrence in Singapore, it does still happen from time to time especially during the Southwest Monsoon season from June to September. Haze is traditionally an atmospheric phenomenon where dust, smoke and other dry particles obscure the clarity of the sky. Though not a common occurrence in Singapore, it does still happen from time to time especially during the Southwest Monsoon season from June to September. Haze@SG is useful utility that allows you to check the hourly Pollutant Standards Index (PSI) on the go. PSI is a measurement developed by the United States Environmental Protection Agency (USEPA) which provides an accurate, timely and easily understandable indicator of daily levels of air pollution.