Should I check the 1-hour PM2.5 or the 24-hour PSI?
Use the 1-hour PM2.5 to decide what to do in the next hour, and the 24-hour PSI to plan tomorrow. The PSI is a 24-hour rolling average, so it moves slowly.
Singapore now
Check your area →45 µg/m³ · Normal (1-hour PM2.5, model estimate, not official)
How NEA frames it
NEA's guidance has two tables: immediate activities by 1-hour PM2.5 band, and planning for tomorrow by 24-hour PSI band, with separate advice for healthy people, vulnerable people and those with chronic lung or heart disease.
Related guides
Related questions
Sources
- NEA 1-hour PM2.5 readings (Singapore) — National Environment Agency (NEA), Singapore · official site · API / docs
- NEA 24-hour PSI (Singapore) — National Environment Agency (NEA), Singapore · official site · API / docs