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What are Some Risks When Working in a Building After a COVID-19 Closure?

Written by Barb Epstien, MPH, CIH Industrial Hygienist

For many companies, managing COVID-19 risks has included prolonged building closures, and many in-person operations have been brought to a halt. Building owners and operators who took steps during shutdown to assure that their water and related mechanical systems were carefully maintained and monitored are more likely to be ready to reopen safely as the pandemic subsides. However, building owners who did not consider those impacts (e.g., low or no occupancy, disruptions in water service, and limited maintenance and cleaning staff availability) will likely face challenges when it comes time to reopen. This is because prolonged periods of building inactivity and reductions in normal water use can degrade conditions and create hazards for returning occupants and others who may work in the building. These include the risk of Legionella and other water-related bacteria growth, as well as humidity issues and mold growth.

Legionella is a bacteria that was discovered after an outbreak among attendees of the American Legion convention at a Philadelphia hotel in 1976. Those who were affected suffered a serious form of pneumonia that eventually became known as Legionnaires’ disease. Legionella bacteria occur naturally in surface waters like lakes and streams. It can become a health concern when it grows and spreads in building water systems, such as cooling towers, potable water systems, and HVAC systems. Stagnant or standing water in a plumbing system can increase the risk for growth and spread of Legionella. Respiratory infection can result from inhaling water droplets or mist containing elevated levels of the viable disease-causing bacteria, which are small enough to pass deep into the lower lungs. People with weakened immune systems are at greater risk, although healthy individuals can also develop Legionnaires’ disease. The closer the contact a person has with the aerosolized water droplets or mist, the greater the exposure risk.

What steps should a building owner take before reopening operations? What questions should a contractor ask before entering buildings that have been inactive for a prolonged period? Some suggestions to consider:

  • Ensure the water heater been properly serviced and the temperature is correctly set, typically to at least 140 degrees F, and in accordance with manufacturers’ instructions.
  • Ensure the building’s water system has been flushed through all points of use (to replace the water inside piping with fresh water) and disinfected. Keep in mind that water that sits stagnant for an extended time in water mains, plumbing lines, and water heaters lose residual chlorine disinfectant. Take care to minimize splashing and aerosol generation during this process.
  • Clean all decorative water features, such as fountains, and follow any recommended manufacturer cleaning guidelines. Make sure these features are free of visible slime or biofilm, and measure disinfectant levels after refilling to assure the water is safe to use.
  • Ensure cooling towers are cleaned and well maintained per manufacturers’ guidelines and industry best practices. Ensure that the tower and basin are free of visible slime, debris, and biofilm, and are disinfected before use.

Respirators may be appropriate for working in enclosed spaces where aerosol generation is likely. Of course, respirators must be used in accordance with an effective respiratory protection program.

For more information, check out CDC’s Guidance for Reopening Buildings After Prolonged Shutdown or Reduced Operation.

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