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Sulfur Dioxide: Reducing Exposure Both Indoor and Outdoor

Factory building.

Sulfur dioxide (SO2) is one of the most common air pollutants. SO2 infiltrates the air we breathe and effects our health in numerous ways, leaving short to long term effects depending on exposure levels. While sources of SO2 may not be within your home, the pollutant will find its way indoors through outdoor access points such as doors and windows. If not properly managed, this buildup of indoor sulfur dioxide may lead to higher exposure.

What is Sulfur Dioxide?

Sulfur dioxide or “SO2” is a colorless gas with a pungent odor. SO2 is part of a larger group of gaseous sulfur oxides (SOx). It is of greatest concern out of the groups of SOx since it is found in higher concentrations than other gaseous SOx, such as SO3.

How Can I Be Exposed to Sulfur Dioxide?

Exposure to sulfur dioxide may occur through inhalation, or skin / eye contact. The most common way people are exposed to SO2 is through inhalation. Once the SO2 enters your lungs, it can then enter the bloodstream. In order to leave your body, the SO2 will break down and exit through the urine.

Health Effects of Sulfur Dioxide

Health effects of SO2 may vary based on concentration level, length of exposure, and form of exposure. Below, we’ve broken down each of the potential health effects from sulfur dioxide.


Inhalation of SO2:

  • Sneezing and coughing
  • Chest tightness
  • Burning of the nose, throat and lungs
  • Difficulty breathing
  • Harm to the respiratory system
  • Aggravation to diseases such as asthma and emphysema
  • Short-term exposure to high levels SO2 may be life threatening

Skin/eye contact with SO2:

  • Irritation of the eyes
  • Frostbite
  • Stinging pain, redness, and blisters


Inhalation of SO2:

  • Changes in lung function
  • Decreased fertility in men and women
  • Loss of smell
  • Headache and dizziness
  • Nausea and vomiting
  • Bronchitis and shortness of breath

Skin/eye contact with SO2:

  • Severe corneal damage

Who is Most at Risk from Sulfur Dioxide?

To some extent, everyone can be affected by sulfur dioxide. However, there are people who are more sensitive or experience higher levels of exposure. These groups include the following:

  • Those most sensitive to SO2 include children, elderly, and people with asthma, heart disease or lung disease.
  • Workers in plants where SO2 occurs as a by-product can experience higher levels of exposure at higher concentrations.
  • People who live near heavy industrial activities that involve a process that produces SO2, such as copper smelting.
  • Those who are near a volcanic eruption.

What Are the Sources of Sulfur Dioxide?

Sulfur dioxide is sourced both naturally and through human activity. Below are some of the overarching sources that contribute to SO2 pollutants.

  • Volcanic eruptions are a natural source of SO2.
  • Burning of fossil fuels by power plants, and other industrial facilities are the biggest source of SO2. Manufacturing of sulfuric acid, paper, food preservatives, and fertilizers.
  • Locomotives, ships and other vehicles and heavy equipment that burn fuel with high sulfur content emit SO2.

How Can I Prevent or Reduce Exposure to Sulfur Dioxide?

Preventing or reducing the direct sources of SO2 may be more difficult, especially emissions from natural sources like volcanic eruptions. Fortunately, there are other solutions to preventing or reducing your exposure to SO2.

  • Limit time spent outdoors while levels of air pollution are high. SO2 is one of many pollutants that should be avoided. Avoiding high levels of air pollution will reduce exposure to more pollutants than just SO2.
  • Live further away from any power plants or other areas with heavy industrial processes nearby.
  • Use safety equipment. Since workers typically breath in the sulfur dioxide from their work environment, they do not bring it home with them. However, the workers can limit their exposure by wearing masks and other required safety equipment at work.
  • Utilize air cleaners, such as an air purifier, within indoor spaces to help improve the quality of your indoor air.

Environmental Effects of Sulfur Dioxide

The effects of sulfur dioxide don’t stop at human health. SO2 also plays a role in the environment that we live in, by contributing to harmful factors on it including:

  • Acid rain: SO2 and other sulfur dioxides can contribute to acid rain. Acid rain is any form of precipitation, wet or dry, with acidic components. This rain contributes to the pollution of our air while causing harm to the environment.
  • Visibility: SO2 and other sulfur dioxides may react with other compounds forming a haze. Haze is a basic form of air pollution that degrades visibilities in places like cities and scenic areas.


Any steps that can be taken to reduce emission or exposure levels of sulfur dioxide is a good idea as it effects both human health and the environment. Those who are at risk should pay closest attention to their levels of exposure. While complete elimination of sulfur dioxide in the air is impossible due to natural sources, there are methods of reducing both emissions from human activity and exposure from all sources. Reduction of indoor sulfur dioxide pollution is the easiest to manage as the air is typically more contained within the walls of the home or building.

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