While some city facilities have reopened, others remain
closed. Microbial hazards such as mold and Legionella, the cause of
Legionnaires’ disease, can develop in facilities without proper care during the
shutdown or without proper precautions prior to reopening.
Potential Hazards
Mold and Bacteria:
Mold and bacteria thrive in moist conditions. When buildings
are unoccupied for long periods of time moisture problems may go undetected
allowing mold and bacteria to spread. Leaks from roofs and plumbing can deposit
moisture and remain undetected while buildings are unoccupied if not inspected
on a regular basis. Additionally, traps in floor drains, toilets, and sinks can
dry out allowing moist, bacteria-infested sewer gas to flow into a building and
collect on ceilings, walls, floors, curtains, and furniture.
Mold and bacteria can also spread throughout a building if
furnace filters became damp and contaminated during shutdown and the HVAC
system is put back in use before replacing the filters. If HVAC systems with
manually adjusted humidifying units have been operating during the shutdown
with limited supervision, the humidifier may still be at winter settings
introducing excessive moisture through the air distribution network.
People can be exposed to mold through skin contact,
inhalation, or ingestion. Individuals who are immunosuppressed are at increased
risk for infection from mold.
Legionella:
Legionella is a naturally occurring bacteria that can be
found in lakes, rivers, ground water, and thus water distribution networks,
and, if present, it bacteria is normally found at a very low level. Legionella
grows best in large, complex water systems that are not adequately maintained
at temperatures between 77-108 o F. During prolonged facility shutdowns hot
water lines are idle for long periods of time and the water temperature can
fall into the Legionella growth range. Additionally, building operators may
lower the temperature level of water heaters trying to save on fuel costs, but
in doing so may be creating an environment where Legionella or other bacteria
can multiply. In cold water lines where building air conditioning systems are
not operating during shutdowns the ambient temperature around stagnant water
lines and cooling towers can also fall into the Legionella growth temperature
range.
Inhalation is the most common route of exposure for
Legionella. The breathing in of small water droplets containing Legionella
allows the microbes to enter the respiratory system. This transfer of water
into a breathable source can include cooling towers, sinks, toilets, showers,
decorative fountains, and hot tubs.
Double Jeopardy
Coronavirus is a respiratory virus usually affecting the
lungs and weakening the immune system. Combining the respiratory hazards and
immune deficiency issues created from the COVID-19 pandemic with an additional
respiratory infection hazard from mold, Legionella, or other forms of bacteria
can only make a bad situation worse. The most at risk individuals are people
with pre-existing conditions like asthma, have allergies to mold, or have a
weakened immune system.
Guidance
Fortunately, there is no need to reinvent the wheel as you
plan to safely reopen your buildings. You can refer to the CDC Guidance for Reopening Buildings After Prolonged Shutdown or Reduced Operations. This CDC
guide will cover minimizing mold and Legionella as buildings reopen risk in
significant detail.
Looking for more information? Here are more resources you
can explore:
Submitted by: Joe Gehrts, Senior Loss Control Coordinator
