What Is Vog?
The USGS describes vog as a hazy mixture of sulfur dioxide gas and aerosols made up mainly of sulfuric acid droplets and other sulfate compounds, formed when sulfur dioxide and other volcanic gases react in the atmosphere with oxygen, moisture, dust and sunlight over minutes to days. It says the particles in vog are fine particles smaller than 2.5 micrometers that can travel deep into human lungs.
The USGS says people vary in their sensitivity, but many Hawaii residents and visitors report sore eyes and throat, runny nose, headaches, cough, phlegm, breathing difficulties, increased susceptibility to respiratory ailments and a general lack of energy. An earlier USGS fact sheet says vog poses a health hazard by aggravating preexisting respiratory ailments, and that acid rain can leach lead into household water supplies.
For volcanic gases, the CDC says to move away from the area immediately if symptoms start, and that symptoms should improve or stop once you are away from the gases. To limit exposure, it advises going indoors, closing and locking outside doors and windows, and turning off heating and air conditioning units and fans.
Sources checked September 15, 2026. Every point below links the page it came from.
The sources behind this answer
- Government sourceThe USGS describes vog as a hazy mixture of sulfur dioxide gas and aerosols made mainly of sulfuric acid droplets and other sulfate compounds, formed as volcanic gases react in the atmosphere. US Geological Survey ↗
- Government sourceThe USGS says the particles in vog are PM2.5, less than 2.5 micrometers in diameter, and that these fine particles can travel deep into human lungs. US Geological Survey ↗
- Government sourceThe USGS says many Hawaii residents and visitors report vog complaints including sore eyes and throat, runny nose, headaches, cough, breathing difficulties and a general lack of energy. US Geological Survey ↗
- Government sourceA USGS fact sheet says vog poses a health hazard by aggravating preexisting respiratory ailments, and that acid rain can leach lead into household water supplies. US Geological Survey ↗
- Government sourceThe CDC says that if you start to have symptoms from volcanic gases, move away from the area immediately, and symptoms should improve or stop once you are away from the gases. CDC ↗
- Government sourceTo limit exposure to volcanic gases and ash, the CDC advises going indoors, closing and locking outside doors and windows, and turning off heating and air conditioning units and fans. CDC ↗
Sources checked September 15, 2026. A brand statement is the company’s own claim, which we report but have not verified. Our grades are model-based estimates, not lab tests.