Solid Science Practical Solutions


Environmental Building Hazards Following the Pandemic Shutdown

As building owners and managers begin planning for re-occupancy of shutdown or reduced operation buildings, it is critical to address the risk of COVID-19 and other hazardous exposures to building occupants.  Five key categories of risk and recommended steps are outlined below.


Of course, COVID-19 is the primary current concern and the ongoing pandemic requires that building managers implement an Infection Control Plan that provides a framework for reducing the risk of any future virus transmission.  Key components include the use of controls (physical barriers), surface cleaning and disinfection, limitations on occupant pathways and density, personal protective equipment (PPE) and employee screening, training and work practices.


Building owners should also evaluate the building and its mechanical and life safety systems to determine if the building is ready for safe occupancy. In addition to COVID-19, this should include checking for environmental hazards associated with prolonged facility shutdown such as:


  • Legionella 
  • Lead in Drinking Water
  • Mold
  • HVAC System Issues


Unoccupied buildings can pose considerable multiple risks to returning occupants.  It is only through careful planning and a proactive program that the risks can be controlled before they become more serious threats to the health and safety of staff and visitors.  




Buildings that have been completely or partially vacant for months pose a limited risk for COVID-19 exposure, since the latest research (which is ongoing) shows that the virus generally survives from 3-4 hours to 3-4 days on various environmental surfaces.  However, the risk level increases dramatically as people return and operations begin to return to normal levels. 


What You Can Do:


Develop a comprehensive re-occupancy plan which:

  • is based on the latest public health findings and guidelines issued by authoritative organizations such as the WHO, CDC, State and local Health Departments, etc. 
  • is practical and flexible so it evolves with new developments
  • clearly defines goals and responsible persons
  • provides specific preventive procedures (including cleaning and disinfection) designed for your operations
  • includes monitoring, enforcement and documentation actions
  • provides training and ongoing communications to managers and workers


How GSE Can Help:


  1. GSE’s expert scientific team can develop a written plan and provide training and ongoing consultation to promote compliance and control disease transmission
  2. GSE’s pre-qualified remediation contractors can clean and disinfect using state of the art equipment and procedures – all under the technical guidance of GSE’s Industrial Hygiene experts
  3. GSE can provide surface testing to determine “biological cleanliness” to identify high risk surfaces and document effective disinfection




Legionella bacteria are responsible for causing Legionnaire’s Disease, a serious and common respiratory illness.  It is estimated that this disease and Pontiac Fever (a less severe form of the disease) represent over 4% of all community acquired pneumonia.  Temporary shutdown of buildings can result in stagnant water in the building’s plumbing system.  Such stagnant water can increase the risk for growth and spread of Legionella and other biofilm-associated bacteria.  The stagnant water can cause hot water temperatures to decrease to the Legionella growth range (77–108°F) and levels of chlorine to be reduced below effective concentrations.


What You Can Do:


  • Establish a comprehensive “Water Management Program” for your building(s). 
  • Review building plumbing plans and eliminate dead zones where water can stagnate.
  • Be sure that hot water remains above 120°F throughout the distribution system.
  • Regularly flush infrequently used sections of the water system.
  • Have water towers, tanks, etc. regularly cleaned, sanitized and tested.
  • Regularly remove and sanitize (or replace) aerators, showerheads, ice machines, and other outlets associated with aerosolized or stagnant water.
  • Have HVAC systems regularly inspected for evidence of stagnant water, corrosion, and mold which can indicate a high risk for Legionella growth.
  • Hire a qualified environmental consultant/Industrial Hygienist to periodically test high risk water outlets for Legionella organisms and assist you in establishing and managing an effective program.  Testing is generally most useful during warm weather seasons.


How GSE Can Help:


  1. We can develop a comprehensive water management program (WMP) for your building’s  water system in accordance with current CDC, USEPA and other authoritative guidelines.   The WMP will include such topics as:
    1. Background on Legionella organisms and Legionnaire’s Disease
    2. Establishing program management team and procedures
    3. Identifying high risk plumbing infrastructure
    4. Water and equipment maintenance criteria
    5. Water testing protocols and standards
    6. Remedial and control options
    7. Monitoring, enforcement and documentation of the program
    8. Forms for program management
  2. Design and conduct building survey(s) to identify possible high risk conditions.
  3. Design and conduct a water testing program for high risk locations.  Test results deliver critical data to guide decisions and provide documentation of effective remedial efforts.
  4. Interpret lab test results and develop site-specific remedial action plans as indicated.
  5. Oversee system disinfection and other remedial steps via our network of qualified partners. 
  6. Design and assist in effective communication strategies and programs for all stakeholders.


Useful Links for additional information:





LDW typically affects older buildings constructed before 1986 which frequently contain lead plumbing components that can leach lead into the drinking water.  The problem can be made worse if the source of potable water is acidic or low in minerals since those conditions can expedite corrosion and leaching of lead from older service connections, pipes, solder or brass fittings.  Further, if the water stagnates in the plumbing system during building shutdown, the lead and other contaminants can accumulate in the water.


What You Can Do:


  • Search for your water supplier, to see the results of their testing at: . Enter your County and Town and open the link to your supplier.
  • Open this link to see if your water provider has found elevated lead and what they are doing about it
  • Check with your water company and municipality to see if they know whether you have lead service lines into your building(s).
  • Contact a plumbing contractor that is knowledgeable about your building(s) to do a plumbing survey to document if lead or brass containing plumbing is present in your distribution system.
  • Have your drinking water tested by a qualified consultant at a NJ Licensed Drinking Water laboratory.


How GSE Can Help:

  1. Conduct a building survey to identify high risk water outlets and review available building plans and records to assess the risk of lead exposure.
  2. Collect selected drinking water samples in accordance with USEPA and NJ protocols, for lead analysis at our affiliated accredited laboratory.
  3. Interpret lab results and provide a detailed report of findings and recommendations.
  4. Provide technical consultation as needed to guide remedial efforts.
  5. Assist in properly communicating related findings and risks to stakeholders.




The temporary shutdown or reduced operation of a building can create mold hazards for returning occupants.  Lack of or reduced ventilation can promote damp stagnant conditions that will promote mold growth on certain high risk building materials such as, ceiling tiles, wallpaper, insulation, drywall, porous wood, carpet, fabric, and cardboard.  Undetected moisture from leaks or condensation from roofs, foundations, windows, or pipes may not be addressed quickly enough during a shutdown to prevent mold damage.  Medical research has confirmed that mold can contribute to negative human respiratory effects.  People with asthma, other respiratory conditions, mold allergy, or weakened immune systems are at elevated risk of health problems from mold exposure.


What You Can Do:

  • Maintain heating and cooling systems to provide fresh air and keep relative humidity below 55%.  Relative humidity can be monitored via a handheld or continuous monitoring hygrometer (RH meter).
  • After a prolonged shutdown and before occupants return, conduct a building inspection to identify signs of moisture and/or mold growth.  Address the source of moisture immediately to prevent further mold growth.
  • Contact a qualified Industrial Hygienist who is trained to recognize and evaluate water intrusion and mold through visual observation and specialized equipment.
  • Operate the HVAC system that has been inactive or at reduced levels during a prolonged shutdown, for at least 48 to 72 hours (known as a “flush out”) before occupants return.  During the flush-out, open outdoor air dampers to the maximum setting that still allows desired indoor air temperatures.
  • Change dirty HVAC filters and inspect the interior of air handlers for evidence of moisture, corrosion and mold.


How GSE Can Help:

  1. Conduct expert water intrusion and mold inspections, testing and consulting to ensure that conditions are addressed properly.
  2. Prepare a fully documented report including methodologies, findings, discussion and detailed recommendations.
  3. Provide remediation project management including identifying, selecting and overseeing a qualified mold remediation contractor.
  4. Conduct post remediation verification (clearance) inspection and testing to be sure that conditions are safe for occupancy.
  5. Provide ongoing consulting to establish an effective preventive program.




HVAC systems should be evaluated prior to reoccupying building to ensure occupant protection and limit the risk of infection from airborne viruses, such as Covid-19, as well as bacteria and fungi (mold).


What You Can Do:


  • Ensure that building HVAC systems operate properly. For systems that have been shut down or on setback, review start-up guidance provided in ASHRAE Standard 180-2018, Standard Practice for the Inspection and Maintenance of Commercial Building HVAC Systems.
  • Increase circulation of outdoor air by opening system dampers as much as possible and open windows and doors and use fans as weather allows. 


How GSE Can Help:

  1. Conduct a building survey to review the HVAC system design, operation, sanitation and maintenance. (For public employers in NJ this information should be referenced in the employers Indoor Air Quality plan).
  2. Conduct indoor air quality (IAQ) measurements for temperature, relative humidity and carbon dioxide to help evaluate the effectiveness of the HVAC systems and to maximize the introduction and distribution of fresh air into occupied indoor spaces.
  3. Conduct ventilation testing and building pressurization studies to help building owners make adjustments to, or improve the performance of HVAC systems, particularly in potentially densely populated building areas.
  4. Provide technical consultation as needed to guide any remedial or HVAC improvement efforts.
  5. Assist in properly communicating related findings and risks to stakeholders.


Unoccupied buildings can pose considerable multiple risks to returning occupants.  It is only through careful planning and a proactive program that the risks can be controlled before they become more serious threats to the health and safety of staff and visitors.