For more information about National Park Service air resources, please visit http://www.nature.nps.gov/air/.


Sulfur Dioxide Effects on Health

Halema'uma'u plume
The Halema'uma'u plume in Kilauea Crater at Hawai'i Volcanoes NP contains extremely high levels of sulfur dioxide, about 500-1,000 tones/day. The NPS sulfur dioxide advisory program alerts the public and park staff if air quality conditions reach unhealthy levels.

What is sulfur dioxide?

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

The primary 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 periodically has extremely high concentrations of sulfur dioxide — far higher than any other national park or even most urban areas.

How can sulfur dioxide affect your health?

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, particularly during heavy physical activity. The resulting symptoms may 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 aggravate existing heart disease in sensitive groups. This gas can also react with other chemicals in the air and convert to a small particle that can lodge in the lungs and cause similar health effects.

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Who is at risk?

People particularly sensitive to sulfur dioxide include:

  • People with lung diseases, such as asthma, chronic bronchitis, and emphysema will generally experience more serious health effects at lower SO2 levels.
  • Children are at higher risk from SO2 exposure because they are more likely to have asthma, which may be aggravated by SO2 exposure. Their lungs are still developing.
  • 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 vigorously 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 may be exposed to unhealthy levels of pollution. Because it is not possible to control volcanic activity, the National Park Service developed a sulfur dioxide advisory program and issues warnings to alert people when unhealthy levels of this gaseous pollutant are present. Advisories encourage people to limit their exposure when it is appropriate.

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How can I avoid unhealthy exposure?

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 potentially unhealthy sulfur dioxide pollution occurs, your chances of being affected increase with strenuousness of your activity and the length of time you are active outdoors. If your planned activity involves prolonged or heavy exertion and the sulfur dioxide levels are high, you may want to limit or discontinue your activity. For recommended protective measures at high levels of sulfur dioxide, consult the Health Advisory Table.

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What are the NPS sulfur dioxide health advisories?

A SO2 air pollution advisory program was established at Hawai'i Volcanoes NP to provide timely information about potentially 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:

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The SO2 and weather data used in this program are collected by the National Park Service at the Jaggar Museum and Kilauea Visitor Center monitoring sites. The SO2 concentrations measured at the monitoring sites are reviewed every 15 minutes and one of six advisory levels of health concern are assigned for that 15-minute period for each site.

How does sulfur dioxide affect national parks?

Hawai'i Volcanoes NP is significantly impacted by sulfur dioxide because the high levels create a human health concern. Additionally, sulfate particles can create haze and reduce visibility at Hawai'i Volcanoes NP and other national parks. Sulfur dioxide can chemically convert to acids in the atmosphere and deposit out in rain, snow, fog, or as dry particles. Such atmospheric deposition can damage vegetation, affect soils, acidify lakes and streams, and ruin memorials, buildings, and statues at our national cultural monuments.

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Last Updated: January 10, 2013