Case Study On Construction Infection Control

Indoor Air Quality & Mould
PEN #20

The first of its kind in Canada and possibly North America, the Construction Infection Control Project was completed within a Nursing Station serving an active Blood and Marrow Transplant (BMT) Unit at the Health Sciences Centre (HSC) in Winnipeg, Manitoba while it remained fully operational.

Pinchin Environmental Ltd. (Pinchin) acted as the infection control consultant and through a team approach with HSC's Maintenance Services Department, Infection Control Department, Unit Staff and Winnipeg Regional Health Authority, was successful in renovating the station whilst patient care in the BMT Unit continued.

The Unit serves patients receiving blood and marrow transplants and other organ related treatments. In most cases their immune systems are artificially suppressed. These patients are at a greater risk of developing Nosocomial (hospital related) infection compared to most other patients; therefore any activities resulting in the generation of dust must be carefully monitored.

Negative AirParticulate generated during construction or renovation activities can contain mould known as Aspergillus. As Nosocomial Aspergillosis is often associated with construction activities, isolation of the work area and monitoring of the work area and monitoring activities become key components of construction in these and similar areas. Numerous published reports have linked construction activities in hospitals to outbreaks of Aspergillosis which have had fatal outcomes to multiple patients.

DemolitionThe BMT Unit’s nursing station was in need of an upgrade which required demolitions, new construction as well as electrical and mechanical upgrades. In reference to the CSA Guideline Z317.13-03 “Infection Control during Construction or Renovation of Health Care Facilities” and Health Canada’s document titled, “Construction - related Nosocomial Infections in Health Care Facilities”, the construction work was classified as a Type D activity which required Class IV procedures and precautions to protect the patients classified as a Group 4 (highest risk) population.

Prior to the start of any dust generating activities, baseline air samples were collected. These included measurements for airborne particulates and mould respectively by use of a portable aerosol monitor and an N6 multi-hole impactor, high flow pump and suitable growth media. The analysis of mould air samples identified the total concentrations and mould species by culturing of viable spores.

The samples were analyzed at the Pinchin Environmental Microbiology Laboratory, located at the Mississauga head office. The Pinchin laboratory is accredited for culture and direct microscope fungal analysis by AIHA-Laboratory Accreditation Programs, LLC Environmental Microbiology Laboratory Accreditation Program and participates in the AIHA-LAP, LLC Environmental Microbiology Proficiency Analytical Testing Program.

Each sample was cultured for 5 days after which colonies were counted. Representative colonies were then transferred to secondary media and then incubated for 7 to 10 days after which they are identified to the Genus or Species level based upon current fungal taxonomic keys. Upon receipt of the laboratory report, the results were interpreted and made available to HSC.

Based on the above published standards Pinchin developed site specific procedures for the isolation of the construction area and inspected all phases of the work until completion.

The Hoarding LineThe construction portion of the work was performed by the HSC In House team and was completed over a six week period. Pinchin provided on-site training and advice to the HSC’s In House team on establishing containment and minimizing particulate generation during performance of the work. BMT Unit staff and HSC’s Infection Control department also provided valuable input and were kept informed on all phases of the project.

ContainmentContainment included installation of slab-to-slab hoarding walls to isolate the work area, negative air pressure to 0.035 inches water column in the work area relative to adjoining patient areas and isolation of the HVAC system. To assist in evaluating the effectiveness of the containment during the construction phase, particulate measurements, with instantaneous results, were collected on a daily basis within the construction area, the active BMT Unit (both inside and outside of patient care rooms), and outside the BMT Unit.

Pinchin’s findings indicated that concentrations measured outside of the construction area remained similar to those of the baseline measurements. Mould air samples for viable spore analysis were collected on a weekly basis in the same locations as those of the particulate measurements. Analytical results of the mould samples did not identify any Aspergillus in the Patient Care Rooms. The total concentrations of mould within the occupied BMT Unit were similar to that of the baseline measurements.

The controls and procedures implemented (hoarding walls, HVAC isolation, negative pressure, etc.) was found to be effective in minimizing the risk of nosocomial infection by containment and prevention of particulate from the construction area migrating into the high risk patient area.

The team approach of developing infection control strategies, inspecting the construction area during all project phases, combined with air monitoring (particulate and airborne mould) ensured and demonstrated the success of this project. This approach is becoming widely recognized as necessary in all health care construction. It is the standard expected of construction when hospitals remain operational during renovations.