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What Are the Dangers of Sulfur Dioxide in Road Pavement?

Typical roadway asphalt consists of sand, gravel, stones, and asphalt cement. Currently, manufacturers within the roadway industry are changing asphalt composition with the addition of sulfur. Sulfur is a chemical element that has a bright yellow color. Sulfur's simple elemental structure makes it easy to manage during manufacturing processes, improving asphalt's overall composition. However, sulfur emits sulfur dioxide gas that is harmful to workers during pavement application.

  1. Sulfur In Asphalt

    • Some countries with perform petroleum and gas refining industries have enacted strict legislation regarding the sulfur levels in end use fossil fuel products. As a result of the stricter refining process, excess sulfur abounds in many countries. Subsequently, new uses for sulfur were needed. One of the most common uses was placing sulfur into asphalt compositions. Sulfur facilitates a faster curing time, high corrosion resistance and overall mechanical strength.

    Respiratory Tract Effects

    • Sulfur dioxide emits from hot sulfur asphalt as it is mixed before application at a job site. Workers can inhale the gas, which immediately irritates the sensitive internal mucous membranes of the nose and throat. The irritation caused is from the sulfur dioxide gas' reaction with the moist mucous membranes which creates sulfuric acid. The onset of irritation can include dryness, pain and burning. In fact, the sense of smell may be altered temporarily as a side effect.

    Gastrointestinal Effects

    • The emitted sulfur dioxide gas can also adhere to saliva, generating sulfuric acid. Swallowed saliva enters the stomach, eventually irritating the stomach lining. In fact, sulfur dioxide dissolves easily into the internal organs, causing vitamin B and C deficiencies.

    Chronic Exposure

    • Workers exposed to sulfur dioxide gas on a consistent basis develop chronic symptoms. Conjunctivitis, or pink eye, occurs from the generation of sulfuric acid within the eye's fluid. The nose's septum can develop an ulcer, causing nasal bleeding. In extreme cases, emphysema and chronic bronchitis may develop together, affecting oxygen intake.

    Lung Function

    • Sulfur dioxide reduces lung function. The lungs cannot expel carbon dioxide as well as they did before sulfur dioxide exposure, causing the person to inhale more oxygen as compensation. In addition, high levels of sulfur within the blood occur as a result of inhaling the sulfur dioxide. However, this condition generally is not chronic, appearing sporadically over time.

    Prevention

    • Workers involved with sulfur asphalt should wear protective respiratory masks, as well as gloves. Although sulfur dioxide is typically inhaled, the gas can also adhere to the skin, causing irritation. Report any symptoms to supervisors immediately for the safety of everyone in the work area.

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