Vapors

Vapors are the gaseous form of substances that are normally in a liquid state at room temperature and pressure. They are formed by evaporation. Like gases, vapors are measured as a percent volume of air, or ppm.

Vapors may be formed when liquids are heated, such as steam created from boiling water, and some solvents form vapors without being heated.

Most vapors found at construction sites come from solvents. A solvent is a substance, most likely a liquid, which dissolves another substance. Common solvents are in paint thinners and adhesives. Many solvents used in construction cause some form of dermatitis - skin dryness, cracking, redness, and blisters. However, when inhaled, solvent vapors can enter the blood stream and travel to other parts of the body, particularly the nervous system, resulting in a toxic exposure.

The temperature at which a liquid gives off vapor is called flash point. How much vapor is released into the air and how quickly the vapor will fill a space is based on a liquid's vapor pressure. All vapor produced by solvents have densities greater than one. Solvents with a higher vapor pressure produce more vapors, making them more hazardous.

Solvents are found in many adhesives and resins, which are used in construction to glue down carpet, sheet goods, tile, roofing and wall materials, and join plastic pipe. Epoxy resins can cause dermatitis and irritate and sensitize the lungs. Symptoms of lung sensitization are similar to asthma, causing wheezing, shortness of breath, and difficulty breathing. Naphthalene is a resin found in coal tar. Exposure to high concentrations of naphthalene can cause fatigue, lack of appetite, restlessness, nausea, vomiting, diarrhea, blood in the urine, and jaundice.

Aromatic hydrocarbons are also common in the construction industry. They are derived from benzene and are used to dissolve rubber, plastics, and paint. Benzene is very hazardous and should be completely avoided. It destroys the bone marrow's ability to produce red and white blood cells, which can cause anemia and leukemia. Toluene is found in paint and may be used as a substitute for benzene. It can cause irritation to the skin and inhalation can affect judgment and reflexes.

To learn more about Construction Chemical Hazards visit our Construction Chemical Hazards & Toxic Substances Online Training web page.