Hazard Awareness for Substation Workers
When performing work at an electrical substation, the obvious hazard – electricity – must be identified and addressed. But electricity is just one of a number of hazards potentially present in this working environment that may also serve as an employee reporting center, control station or storage area. Other possible hazards include thermal stress; noise; slip, trip and fall hazards; animal waste; and nonionizing radiation.
And around the country, especially in larger cities, substations may be enclosed or have large supervisory buildings, some of which were constructed in the early 20th century. It was common for facilities constructed before the 1960s or 1970s to be insulated and painted with materials – like asbestos and lead – that are recognized today as serious health hazards. Even if you aren’t exposed to 60-year-old substations, you may come into contact with these old construction materials, and knowing how to protect yourself is critical for you and your family.
Asbestos and Lead Hazards
The use of asbestos in the manufacture of building materials became popular in the late 1800s. The mineral was inexpensive, durable and flexible, with good insulating and fireproofing properties. Potential asbestos-containing building materials in today’s older substations include fire doors; fire blankets; floor tile and associated mastics; pipe insulation; wall boards; window caulk; window glazing; and roofing materials. If building material contains more than 1 percent asbestos as determined by polarized light microscopy analysis, the material is classified as asbestos-containing material. Asbestos becomes a hazard when the building material is damaged or disturbed and fibers are released into the air. While airborne, fibers can be inhaled or ingested into the body. OSHA has established a permissible exposure limit (PEL) of 0.10 fibers per cubic centimeter of air as an eight-hour time-weighted average, and an excursion limit of 1 fiber per cubic centimeter of air over a 30-minute sampling period. This means that an employee may be exposed to asbestos above the PEL for a limited time period – up to 1 fiber per cubic centimeter of air within a half-hour – but the eight-hour exposure average cannot be above the PEL. After exposure, asbestos fibers can become stuck in the lung tissue and can cause asbestos-related diseases or conditions, such as asbestosis, mesothelioma or lung cancer.
Substations may also contain lead-based paint used on various surfaces throughout the building. During manufacture, lead is added to the paint to decrease drying time, increase durability, enhance appearance and control corrosion. The U.S. Department of Housing and Urban Development (HUD) defines lead-based paint as paint with lead levels equal to or above 1.0 milligrams per square centimeter by X-ray fluorescence or 0.5 percent by weight with laboratory analysis. Exposure to lead dust can occur by inhalation during disturbance – such as sanding or drilling – of painted surfaces and by ingestion caused by improper personal hygiene (e.g., not washing hands after finishing work tasks). Once inside of the body, lead can affect the central nervous system, kidneys and reproductive system. OSHA’s action level for airborne concentrations of lead is 30 micrograms per cubic meter of air averaged over an eight-hour period; the PEL is 50 micrograms per cubic meter of air averaged over an eight-hour period. An action level is the level of exposure to a chemical or physical agent that requires an employer to take precautions – for instance, air monitoring and medical surveillance – to protect the worker. Employers and employees should note that regardless of the amount of lead identified in paint, it is still possible for an employee to be exposed to it.
Humans may not be the only occupants of substation buildings. It is not uncommon for mice, birds and other animals to gain access through open doors, holes or cracks in the building’s walls, or even through the heating, ventilation and air-conditioning (HVAC) system. Older substation buildings, wet areas and poor housekeeping also tend to attract rats and mice. All of these creatures may leave droppings throughout a substation, including inside of the HVAC system, which can present hazards. For instance, human contact with mice droppings that contain viruses can lead to diseases such as hantavirus pulmonary syndrome or lymphocytic choriomeningitis. Exposure may occur by inhaling dust containing the viruses, via the hand-to-mouth route after touching something containing droppings or by eating food contaminated by droppings. Further, bird droppings may contain a fungal spore known as Histoplasma capsulatum. When the spore is inhaled into the lungs, pneumonia-like illness can develop.
When performing certain work tasks, employees may be required to access the roof of the substation building where antennas are located. These antennas are used to transmit signals for cellular telephone service, radio stations, radio communication or television stations. The amount of power generated from these antennas varies based on the type of antenna used. As with all forms of electromagnetic energy, the power decreases as the distance from the antenna increases. Exposure to high levels of radio-frequency radiation causes heating of body tissue or thermal effects, which can lead to tissue damage. This is due to the body’s inability to cope with or dissipate the excessive heat that could be generated.
When working at electrical substations, electricity may not be the only hazard present. To ensure a safe work environment, chemical, biological and physical hazards must be recognized, evaluated and controlled to help prevent exposure that can lead to illness or injury.
About the Author: Dion Creggett, CIH, CSP, MPH, is a senior industrial hygiene administrator with ComEd, an Exelon company. He holds a bachelor’s degree in environmental health and a master’s degree in public health with a concentration in industrial hygiene. Creggett can be reached at firstname.lastname@example.org.