Learn about haze

Long-form reference pages that put the numbers in context. Each starts with a short answer and lists every source.

PSI vs API vs ISPU vs AQI: Southeast Asia's air-quality scales compared

Side-by-side bands for Singapore's PSI, Malaysia's API, Indonesia's ISPU, Thailand's AQI and the US AQI, PM2.5 standards (WHO, US, Singapore, Malaysia, Thailand, Indonesia) and why apps disagree.

Southeast Asian haze history: every major episode since 1997, with the numbers

Peak PSI and API readings, school closures, area burned, costs and health estimates for the 1997, 2006, 2013, 2015, 2019, 2023 and 2026 haze, each with its source.

When is haze season? A month-by-month calendar for Southeast Asia

Haze season in Singapore, Malaysia and Indonesia usually runs June to October and peaks August to October; northern ASEAN's runs January to April. Monthly calendar and ASMC alert levels explained.

Haze glossary: PSI, PM2.5, API, ISPU, hotspots and more

Plain-language definitions of the terms used in Southeast Asian haze reports: PM2.5, PSI, API, ISPU, AQI, µg/m³, hotspots, peat, monsoon, El Niño, ASMC alert levels and more.

Looking for practical advice instead? See the life guides, FAQ and why it is hazy.

General information, not medical advice. Follow your doctor and your school, league or organiser's final call. Data come from official sources; see data sources.