USGS issues Kilauea Lower East Rift Zone Eruption FAQs

USGS issues Kilauea Lower East Rift Zone Eruption FAQs

Kīlauea Lower East Rift Zone (LERZ) Eruption FAQs

This information addresses common questions about the emissions from eruption fissures on Kīlauea Volcano’s Lower East Rift Zone (LERZ), like those in Leilani Estates. At this time, the eruption and response is ongoing and this information was last updated on 11 May 2018.

What are the air pollution hazards from the current eruption in Lower Puna?

The LERZ eruption is different from the 2014 Pāhoa lava flows. The vent for the 2014 lava flows was located close to the Puʻu ʻŌʻō vent, many miles upslope from the current LERZ eruption.

Gas from the lava escaped as the lava flowed downhill.

The active lava flows had already lost much of their gas by the time they entered the Pāhoa community. In the current situation, the eruptive vents are located within or near residential areas.

The lava being erupted contains very high amounts of gas, so the gas concentrations near the lava can be much higher than during the Pāhoa event. These concentrations may be similar to the amount released from the Halema’uma’u lava lake at the Kīlauea summit.

The air pollutants of most concern during the current volcanic activity are:

SO2: sulfur dioxide is a colorless, irritating gas that has an acrid odor like fireworks or a burning match.

Sulfate particles: as SO2 is released, it reacts in the atmosphere and, within hours to days, converts to fine particles called sulfate aerosol. This aerosol includes sulfuric acid droplets.

H2S: hydrogen sulfide is a colorless, irritating gas that smells like rotten eggs.

HCl: There is a small amount of hydrogen chloride gas being released and it is at much lower concentrations than the SO2. This is in contrast to what happens when lava flows directly into the ocean where HCl acid is created as part of the ocean entry plume and is the main hazard.

Burning vegetation, roads and structures produce smoke (particles and gas) which may contain irritating or harmful components.

Are the concentrations from this eruption hazardous?

Very high concentrations of SO2 (spikes above 100 parts per million) have been measured close to the erupting fissures. This is a serious hazard according to the NIOSH Immediately Dangerous to Life & Health threshold (IDLH) of 100 ppm of SO2 (

The gas is diluted with distance from the erupting vents to lower, but variable concentrations, depending on the wind conditions.

In downwind areas in Lower Puna, concentrations as high as 5 ppm have been measured. Hawaii Department of Health (HDOH) considers a 15 minutes average exposure over 5 ppm to be ‘hazardous’ (

Additional air quality monitoring equipment is being installed to measure the concentrations at specific locations farther from the vents.

For information on SO2 concentrations measured daily by monitors located within communities around Hawai’i Island, see

Who is monitoring the air quality in and around Leilani Estates?

The National Guard Civil Support Team is monitoring air quality and advising Civil Defense about air quality conditions directly associated with the eruption.

The HDOH is setting up SO2 and particle monitoring in areas around the eruption site, as they did during the Pāhoa crisis. HDOH data will become available online once the monitoring equipment is up and running.

What should I do to stay safe?

Follow mandatory evacuation orders.

Consider voluntary evacuation if air quality is poor, especially if you are sensitive to health effects from air pollution (such as individuals with pre-existing conditions e.g., asthma, bronchitis, emphysema, lung or heart disease, infants and children, new or expectant mothers, and older adults).

Reduce exposure to the emissions whenever possible:

Limit strenuous activities

Stay indoors and close all doors and windows to the outside and, if possible, seal large gaps under doors or around windows

Reduce indoor air pollution with an air cleaner, if you have one

Restrict vog from entering your vehicle: If driving through the dense volcanic plume adjacent to the erupting fissures, temporarily close your windows, and turn off your fan and air conditioner to minimize air infiltration.

See Vog Protection information on the Vog Dashboard for more details.

What about face masks?

Gas masks are not recommended: Public health officials and medical practitioners do not recommend any kinds of gas masks/respirators as protection from gases for the general public. This is because safe use of respirators requires correct mask and/or filter cartridge selection, fit testing, physician screening, and training on correct use, maintenance and storage.

Sensitive groups: Children or people with pre-existing respiratory conditions should be especially cautious because respirators/masks typically do not fit children and the breathing resistance caused by respirators/masks can worsen symptoms of respiratory disorders.

Effectiveness of particle masks: Basic dust masks, bandanas, or surgical masks will not provide any substantial protection from SO2 or H2S gas or particles. Industry-certified particle masks (e.g., N95) will block particles if worn correctly (see

However, since gases are the main hazard in the LERZ eruption, N95 particle masks, which are not designed to capture gases, are not appropriate or safe. Any respirators/masks will not protect those with beards or moustaches as facial hair interferes with a good seal to the face.

Will there be acid rain?

Rain is acidified by acid volcanic gases like SO2. In areas where the gas plume is present, there is likely to be acid rain. The acidity will depend on the concentrations of gas present during rainfall.

Acid rain can damage plants and accelerate the rusting of metal surfaces on buildings, vehicles, farm equipment and infrastructure, and cellphone towers. Acid rain is likely to kill fish in open air ponds so covering ponds is advised. Acid rain can also irritate the skin and eyes or cause a stinging sensation. Rinsing the skin and eyes with clean water can help.

Information on how to protect water catchment systems can be found at and Filters that neutralize acid catchment water are available commercially.

Where do I go for eruption and emissions information?

USGS Hawaiian Volcano Observatory (HVO) status reports and alerts:

Civil Defense updates and alerts:

The Vog Dashboard which links to Hawaii-wide air quality data and information on vog:

Hawaii Emergency Management Agency information:

Vog forecast: UH Manoa Vog Measurement and Prediction project (VMAP):

National Weather Service (NWS) new wind and weather data at Pāhoa and Puna Geothermal Ventures (PGV) are included on this site:


Mary Greeley News