Guidance for Reopening Buildings After Prolonged Shutdown or Reduced Operation
Source: https://www.cdc.gov/, May 7, 2020
The temporary shutdown or reduced operation of a building and reductions in normal water use can create hazards for returning occupants. Two potential microbial hazards that should be considered prior to reopening after a period of building inactivity are mold and Legionella (the cause of Legionnaires’ disease). For mold, a “prolonged period” may be days, weeks, or months depending upon building-specific factors, season, and weather variables.1 For Legionella, a “prolonged period” may be weeks or months depending on plumbing-specific factors, disinfectant residuals, water heater temperature set points, water usage patterns, and preexisting Legionella colonization.2 Note that additional hazards, outside of those discussed in this document, may exist for returning occupants. These can include other microbial hazards, such as non-tuberculous mycobacteria, changes in water chemistry that lead to corrosion, leaching of metals (such as lead) into stagnant water, disinfection by-products, and sewer gases that enter buildings through dry sanitary sewer drain traps. Read more.
