page_title: 1997 Southeast Asian haze
hierarchical_section_title: 1997 Southeast Asian haze
caption_attribution_description: English: After several relatively quiet fire seasons in Indonesia, an abundance of blazes in Kalimantan (part of Borneo) and Sumatra in September 2019 has blanketed the region in a pall of thick, noxious smoke. Caption by Adam Voiland.
context_page_description: The 1997 Southeast Asian haze was a large-scale air quality disaster that occurred during the second half of 1997, its after-effects causing widespread atmospheric visibility and health problems within Southeast Asia. The total costs of the Southeast Asian haze are estimated at US$9 billion, due mainly to health care and disruption of air travel and business activities.
  The influence of the 1997 fires in Kalimantan and Sumatra on ambient air quality was evident by July and peaked in September/October before weakening by November, when the delayed monsoonal rain extinguished the fires and improved air quality within the region. During the peak episode, satellite imagery showed a haze layer that expanded over an area of more than 3,000,000 km², covering large parts of Sumatra and Kalimantan. Its northward extension partially reached Malaysia, Singapore, Brunei, Thailand and the Philippines and its westward extension reached Sri Lanka. During this period, particulate matter concentrations frequently exceeded national ambient air quality standards.
context_section_description: The 1997 Southeast Asian haze was a large-scale air quality disaster that occurred during the second half of 1997, its after-effects causing widespread atmospheric visibility and health problems within Southeast Asia. The total costs of the Southeast Asian haze are estimated at US$9 billion, due mainly to health care and disruption of air travel and business activities.
  The influence of the 1997 fires in Kalimantan and Sumatra on ambient air quality was evident by July and peaked in September/October before weakening by November, when the delayed monsoonal rain extinguished the fires and improved air quality within the region. During the peak episode, satellite imagery (NASA/TOMS aerosol index maps) showed a haze layer that expanded over an area of more than 3,000,000 km² (1,200,000 sq mi), covering large parts of Sumatra and Kalimantan. Its northward extension partially reached Malaysia, Singapore, Brunei, Thailand and the Philippines and its westward extension reached Sri Lanka. During this period, particulate matter concentrations frequently exceeded national ambient air quality standards. Monthly mean horizontal visibility at most locations in Sumatra and Kalimantan in September was below 1 km (0.62 mi) and daily maximum visibility was frequently below 100 metres (330 ft).
caption: Haze in Borneo, 2019
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