Sulfur Dioxide Effects on Health

Sulfur dioxide (SO₂) is a colorless, reactive air pollutant with a strong odor. This gas can be a threat to human health, animal health, and plant life.

The main sources of sulfur dioxide emissions are from fossil fuel combustion and natural volcanic activity. Hawai’i Volcanoes National Park (NP) is unique in the national park system because it sometimes has extremely high concentrations of sulfur dioxide — far higher than any other national park, or even most urban areas.

Sulfur dioxide irritates the skin and mucous membranes of the eyes, nose, throat, and lungs. High concentrations of SO₂ can cause inflammation and irritation of the respiratory system, especially during heavy physical activity. The resulting symptoms can include pain when taking a deep breath, coughing, throat irritation, and breathing difficulties. High concentrations of SO₂ can affect lung function, worsen asthma attacks, and worsen existing heart disease in sensitive groups. This gas can also react with other chemicals in the air and change to a small particle that can get into the lungs and cause similar health effects.

People sensitive to sulfur dioxide include:

• People with lung diseases, such as asthma, chronic bronchitis, and emphysema will generally have more serious health effects at higher SO₂ levels.
• Children are at higher risk from SO₂ exposure because their lungs are still developing. They are also more likely to have asthma, which can get worse with SO₂ exposure.
• Older adults may be more affected by SO₂ exposure, possibly because they are more likely to have pre-existing lung or cardiovascular disease.
• Active people of all ages who exercise or work outdoors have higher exposure to sulfur dioxide than people who are less active.

Hawai’i Volcanoes NP visitors, residents, and park staff downwind of the volcanic SO₂ emissions can be exposed to unhealthy levels of pollution. Since it is not possible to control volcanic activity, the National Park Service participates in a sulfur dioxide advisory program, which gives out warnings to let people know when unhealthy levels of this pollutant are present. Advisories encourage people to limit their exposure when necessary.

You can take simple steps to reduce your exposure to unhealthy air. First, visit the Current Conditions Website to find out about current sulfur dioxide conditions and the health advisory level.

When possibly unhealthy sulfur dioxide pollution happens, your chances of being affected increase with high levels of activity and the length of time you are active outdoors. If your planned activity has long or heavy physical exertion and the sulfur dioxide levels are high, you may want to limit or stop your activity. For recommended ways to protect yourself at high levels of sulfur dioxide, consult the Health Advisory Table.

What are the NPS sulfur dioxide health advisories?

A SO₂ air pollution advisory program was created at Hawai’i Volcanoes NP to deliver timely information about possible unhealthy air pollution conditions that could affect the health of visitors, island residents, and park personnel. Using the Environmental Protection Agency (EPA) air quality index, the NPS SO2 health advisories for Hawai’i Volcanoes NP help you understand what local air quality means to your health. The air quality index is divided into six levels of health concern: