State: Vog, sulfur dioxide still potential health hazards even while Kīlauea summit eruption paused

State health officials urge the public to take precautions as volcanic gas emissions — and volcanic smog known as vog — remain elevated, producing poor air quality throughout the islands, even while the continuing episodic summit eruption of Kīlauea volcano on the Big Island is again paused following the end of its 18th episode April 22.

Sensitivity to vog varies, so officials advise people to be prepared for and aware of their surrounding air quality conditions and how they might react to them.

Air quality levels at several Hawaiʻi Island, Maui and Oʻahu air monitoring stations have varied since the eruption started Dec. 23, 2024, with periodic increases in sulfur dioxide and fine particulate matter.

As that sulfur dioxide is continuously released from the summit — even during pauses in eruptive and lava fountaining phases — it reacts in the atmosphere to create vog, which can have far-reaching effects downwind from the summit and be hazardous to human health.

While most air quality readings have maintained good or moderate levels, monitoring stations located in the southern part of Hawaiʻi Island have, at times, shown unhealthy air quality.

Air quality can also change quickly, depending on the amount of gas being released from the volcano, wind direction and other weather conditions.

Southerly winds, for example, can transport vog northward up the island chain, increasing concentrations in West Hawaiʻi and other parts of the state, including other islands such as Maui and Oʻahu.

POTENTIAL HEALTH EFFECTS of exposure to increased levels of sulfur dioxide, vog and other fine particulate matter can range from minor irritation to serious health effects, including:

• Eye, nose, throat and/or skin irritation.
• Coughing and/or phlegm production.
• Increased susceptibility to respiratory ailments.
• Fatigue and/or dizziness.
• Rapid or difficult breathing.

There also are PEOPLE AT HIGHER RISK of health problems when in voggy conditions:

• People with pre-existing respiratory conditions such as asthma, bronchitis, emphysema and chronic lung or heart disease.
• Children and infants.
• Elderly people.
• People who work or exercise outdoors.
• Pregnant women.

Health officials offer the following PRECAUTIONARY MEASURES if you find yourself in heavy vog conditions:

• Contact a medical provider if any symptoms develop. Respiratory conditions could worsen rapidly.
• Have medications readily available.
• Reduce strenuous outdoor activities and time spent outdoors to limit exposure and minimize health risks.
• Stay indoors and close windows and doors. Set your air conditioner to recirculate indoor air. Keep your car windows closed and set the car’s air conditioner to recirculate.
• Do not smoke and avoid secondhand smoke.
• Drink plenty of fluids to avoid dehydration.
• Use air purifiers that can reduce particulates and sulfur dioxide (vog.ivhhn.org/vog-protection).
• Consider leaving areas with poor air quality for locations with improved conditions.
• Have family emergency plans prepared and ready.
• Heed warnings from county and state emergency officials.

Short-term use of masks — surgical, cloth, KF94, KN95 or N95 — can help protect against volcanic ash; however, a mask will not be of much difference when it comes to fine particulate matter, sulfur dioxide and vog.

Masks also do not provide effective protection for people with beards or mustaches as they prevent a tight seal to the face.

High risk groups should be especially cautious because N95 or other masks typically do not fit children, and breathing resistance caused by masks can worsen respiratory disorders.

Furthermore, Hawaiʻi Department of Health does not recommend the use of respirators by the general public to protect against volcanic gases.

State health officials encourage residents and visitors to keep a close eye on Hawaiʻi air quality data while volcanic gas emissions remain elevated. The most up-to-date information is available online through:

• Hawaiʻi Interagency Vog Information Dashboard.
• Hawaiʻi Department of Health Clean Air Branch.
• U.S. Geological Survey Kīlauea Volcano Updates.

Guidance for how to reduce exposure and protect your health — including recommended actions and activities should air quality levels become unhealthy — can be found here and in a past “Volcano Watch” article from the Hawaiian Volcano Observatory.