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Online Tools Help Hawaii Breathe Easier During Trade Wind Time-Outs

November 16, 2013
This image, taken by the crew of Space Shuttle Atlantis on May 13, 2009 (after completing the capture of the Hubble Space Telescope), shows volcanic plumes from Kilauea rising up from three locations: Halema‘uma‘u Crater, Pu‘u ‘O‘o Crater, and from along the coastline where lava flows from the East Rift zone were entering the ocean. The plumes have created a blanket of volcanic fog, called vog, that envelops the island. (Image Courtesy NASA Earth Observatory)

This image, taken by the crew of Space Shuttle Atlantis on May 13, 2009 (after completing the capture of the Hubble Space Telescope), shows volcanic plumes from Kilauea rising up from three locations: Halema‘uma‘u Crater, Pu‘u ‘O‘o Crater, and from along the coastline where lava flows from the East Rift zone were entering the ocean. The plumes have created a blanket of volcanic fog, called vog, that envelops the island. (Image Courtesy NASA Earth Observatory)

The following is this week’s edition of “Volcano Watch” from the USGS Hawaiian Volcano Observatory:

We are currently sandwiched between the Halloween and Thanksgiving holidays as the inexorable march of time brings the winter festivals ever closer. For Hawaiʻi, this period also signals the time of year when interruptions in the trade winds become more common.

After 3 decades of eruptive activity on Kīlauea’s east rift, and 5 years of simultaneous summit eruption, island residents have become familiar with the importance of wind conditions in determining the geographical fate of Kīlauea’s noxious gas and particle emissions. Volcanic pollution from Kīlauea, commonly referred to as vog, impacts some part of the Island of Hawaiʻi most days.

The image, acquired by the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite, shows metric tons of sulfur dioxide measured in the lowest 5 kilometers (roughly 3 miles) of the atmosphere around Hawaii. Lowest amounts appear in lavender, and highest amounts appear in red. CLICK IMAGE TO VIEW QUICKTIME ANIMATION. (Courtesy NASA Goddard Space Flight Center)

In a story familiar to most Hawaiʻi residents, prevailing trade winds blow the vog plume to the southwest, affecting areas of Kaʻū and much of the leeward side of the island. Population centers in East Hawaiʻi, including popular areas of Hawaiʻi Volcanoes National Park, are upwind of Kīlauea’s emission sources during trades; thus, they are unaffected by volcanic emissions, and generally have very good air quality. During the winter months, however, when trade winds are absent as much as 50 percent of the time, these areas experience very high concentrations of volcanic gases and particles due to their close proximity to the active vents.

Map showing prevailing Trade Winds and Kona Winds. (USGS)

When trade-winds are absent for prolonged periods, vog travels up the island chain; our disgruntled neighbors have come to understand that the appearance of vog in their area is normally due to lack of trade winds, rather than an increase in Kīlauea’s activity. 
A number of online tools have been developed to help people in Hawaiʻi minimize their exposure to volcanic pollution. The tools provide color-coded alert levels, based on the familiar traffic-light motif, to identify current vog concentrations and forecast future ones. The six-color conditions range from good (green) to hazardous (brown) and are based on human health and environmental studies used by the U.S. Environmental Protection Agency (EPA) to set national air pollution exposure limits.

The SO2 Molecule (Courtesy NASA Jet Propulsion Laboratory)

The components in vog known to affect health are sulfur dioxide (SO2) gas, and tiny respirable particles called PM2.5 (particulate matter with a diameter of 2.5 microns or less, or 1/10 the thickness of a human hair). While both of these pollutants are regulated by the EPA, Hawaiʻi’s advisories for volcanic SO2 and PM2.5 have been customized for local conditions. A shorter exposure time interval has been adopted, since variable wind conditions can cause volcanic gas concentrations to change rapidly.

Four websites are particularly useful for helping individuals stay informed on current and future vog conditions in their general area. The Hawaii State Department of Health provides a short-term SO2 advisory with current 15-minute average SO2concentration data for nine locations ranging from Hilo to Waikoloa (hiso2index.info). The National Park Service provides 15-minute average gas and particle data for 9 and 2 sites, respectively, within Hawaiʻi Volcanoes National Park. The Park data is used by managers to help limit visitors’ exposure to potentially hazardous areas (hawaiiso2network.com).

Current PM2.5 conditions and a one-day forecast are provided by the AirNow group, a partnership of Federal, State, and local agencies (airnow.gov). And finally, an interactive map-based forecast model known as VMAP is operated by the University of Hawaiʻi at Mānoa. This model provides 60 hours of animated gas and particle data and has proved useful for people planning outdoor activities (http://weather.hawaii.edu/vmap).

Individual responses to vog vary widely, although people with pre-existing respiratory conditions, such as asthma or chronic respiratory disease, show special sensitivity. Health studies examining the long-term effects of vog are ongoing; however, documented short-term effects include headaches, breathing difficulties, increased susceptibility to respiratory ailments, eye irritation, and sore throat. A multi-agency response team of State and County organizations recommends protective actions during periods of vog. These include staying informed of air quality conditions, staying indoors during periods of heavy vog, drinking plenty of water, and keeping medications handy (http://governor.hawaii.gov/emergency-information).

Using online tools for monitoring air quality can help determine whether vog in your area, rather than some other environmental (or holiday) stressor, is affecting your well-being. As the season unfolds, we wish everyone good cheer in using available resources to live harmoniously with these beautiful volcanic islands.

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