Health Canada Issues Standard for Construction Precautions in Hospitals

Indoor Air Quality & Mould
PEN #7

A New National Standard

Hospital SymbolHealth Canada has released a national standard for precautions to be taken during construction and maintenance work in hospitals and other health care settings. Contractors performing work in health care facilities must take care to apply these standards with diligence to minimize the very real risk of their work causing illness and death in susceptible patients.

Issued in July 2001, "Construction-related Nosocomial Infections in Patients in Health Care Facilities – Decreasing the Risk of Aspergillus, Legionella and Other Infections" is a guide for the planning of renovations and construction work. Its purpose is to lessen the risk of hospital-acquired (nosocomial infections).

Emergency RoomConstruction and renovation work causes settled dust containing fungal spores and bacteria in water supply systems to become airborne. Patients who are susceptible to infections may become infected by these microbial hazards, in some cases fatally so. The accompanying story chronicles some of the recent outbreaks of nosocomial infections in Montreal’s Victoria Hospital. In fact, all existing hospitals and health care facilities share this potential for illness due to construction work.

The Health Canada standard quotes a number of studies that powerfully demonstrate the need for these precautions. One study showed that the frequency of nosocomial Aspergillus infections tripled in a hospital during construction work (up to 10 cases per 1000 days at risk), compared to baseline conditions. However, following implementation of control measures, the frequency of nosocomial infection was reduced to the baseline level, demonstrating the effectiveness of the methods.

Operating RoomFungal infections, particularly due to fungi of the Aspergillus family, are a major concern of the Health Canada standard.Several Aspergillus species can cause infections in susceptible patients. Aspergillus exposures may occur by a variety of pathways: through infiltration of outside unfiltered air, disturbance of dust in ceiling systems or other cavities, demolition of equipment, or from mould growth in the facility. The risk of Aspergillus infection is greatly increased when mould growth in building finishes or in ventilation units goes unchecked. For this reason, it is essential that managers of health care facilities proceed with utmost care when dealing with water damage or reports of potential health effects from mould contamination.

Examining BlueprintsLegionella bacteria is the second risk factor addressed by the Health Canada standard. Legionella, typically present at low concentrations in lakes and rivers and treated water supplies, can become greatly amplified in water systems given the right conditions of warm water and nutrient matter. If these bacteria become airborne and are inhaled, a serious pneumonia can develop. Outbreaks of Legionnaire’s disease have been tracked to a variety of sources including cooling towers, faucet and shower aerators, spas, drinking fountains and water features. Another risk factor for development of Legionnaire’s disease in hospitals is the possible release of bacteria colonizing stagnant areas of water service caused by pressure surges during service interruptions.

Susceptible patients identified in the Health Canada standard include transplant patients, patients undergoing chemotherapy or prolonged use of antibiotics or steroids, dialysis patients, the very old and very young, patients with AIDS or other congenital immunodeficiencies, and other conditions.

Cleanroom Lab TestingControlling the risk requires the collaborative effort of many involved in a construction project. For smaller scale projects, these would include at least the infection control practitioner at the facility, engineering services, the architects and engineers responsible for the project and of course the contractor and subcontractors. Larger scale renovations may require a specialist consultant to design the containment and ventilation controls and to supervise and test the ongoing isolation methods.

The Health Canada standard is based on a ranking of risk of a construction activity depending on the expected intensity of disturbance and the susceptibility of the surrounding patient population.

Four classes of controls are identified, as shown in Table 1, for the construction activities given in Table 2 and the risk groups given in Table 3.

Canada is not alone in having recently published standards for hospital construction precautions. The US Centres for Disease Control issued a similar document, "Draft Guideline for Environmental Infection Control in Healthcare Facilities, 2001".

Mould Infections Close Operating Rooms at Montreal Hospital

The threat posed by mould growth in hospitals became national news earlier this year when airborne mould and Aspergillus infections closed down most of the operating rooms at Montreal’s Royal Victoria hospital. The hospitals main OR block was closed in February after air testing indicated Aspergillus contamination in the 40 year-old air handling units serving these rooms. The operating rooms returned to service on July 3, four months after they were closed. About one million dollars was spent to replace the ventilation system and upgrade other mechanical services.

Two patients operated on in these rooms in the previous six months were known to have acquired Aspergillus infections, and one has since died. Doctors will follow up hundreds of patients who underwent surgery at Royal Victoria in the previous six months to determine if any were infected by the fungus. If these cases are confirmed as an outbreak related to fungal contamination, they would not be the first at the Royal Victoria. In an article published in 1996, researchers at the hospital reported on a cluster of Aspergillosis cases in a cancer ward between 1989 and 1992, likely related to demolition of an older structure and construction of an addition over that time. In that outbreak, 28 suspected cases were observed. Of those, seven were classified as definitely Aspergillosis, and the remainder as probable or possible.

This fall the Montreal Regional Health Board will approve a set of infection prevention guidelines to be built into every tender call for renovations in Montreal’s network of hospitals.

In a related story carried by CBC Radio in July, at least seven families say they will sue the Royal Victoria Hospital over the outbreak of Aspergillus infection.

Health Canada Issues Standard for Construction Precautions in Hospitals - Tables

Table 1: Matrix to Determine Class of Construction Infection Controls

Construction Activity
Risk Group Type A Type B Type C Type D
Group 1 I II II III/IV
Group 2 I II III IV
Group 4 I-III (Contact IC to confirm) III/IV III/IV IV

Table 2: Construction Activities

Type A Activities that do not generate dust or require cutting of walls or access to ceilings except for visual inspection. Minor plumbing work.
Type B Small scale, short duration work that creates minimal airborne dust.
Type C Work that generates a moderate to high level of dust or requires demolition or removal of fixed building components (such as countertops). Includes sanding of walls, removal of floor-coverings, ceiling tiles, minor duct work, etc.
Type D Major demolition, construction and renovation projects. Major plumbing modifications.

Table 3: Risk Groups

Group 1 Office areas, unoccupied wards, public areas
Group 2 All patient care areas (unless classified as Group 3 or 4), outpatient areas, admission/discharge areas
Group 3 Emergency, radiology/MRI, post anesthesia care, labour and delivery, normal newborn nurseries, nuclear medicine, day surgery, physiotherapy tank areas, general surgical wards, pediatrics, geriatrics, long-term care
Group 4 ICU, operating rooms, anesthesia and pump areas, oncology units and outpatient areas for cancer care, transplant units and outpatient areas for transplant patients, immunodeficiency areas, dialysis, tertiary care nurseries, cardiac catherization and angiography, endoscopy areas, pharmacy admixture rooms, Central Processing Department and Central Inventory Department

Table 4: Summary of Construction Infection Controls

Class 1
  • Immediately replace ceiling tiles removed for inspection. Vacuum the work area following work.
  • Perform water interruptions during low activity periods, flush systems after interruption, check for discoloured water, ensure water temperature meets minimum requirements.
  • Minimize patients’ exposure to work area.
Class 2

In addition to Class I requirements,

  • Provide means to minimize dust creation and dispersal (drop sheets, seal work area at openings, dust mat at entrance).
  • Disable and seal ventilation system.
  • Wet mop and vacuum with HEPA vacuum when work is complete. Wipe horizontal surfaces with disinfectant.
  • Consider hyperchlorination or superheating of stagnant potable water.
Class 3

In addition to Class II requirements,

  • Consult with Infection Control department prior to work.
  • Erect impervious dust barrier, slab to slab, of 2 layers of 6 mil polyethylene sheeting or drywall. Maintain negative pressure within work area by means of HEPA filtered exhaust ventilation.
  • HEPA vacuum work area daily or more frequently.
  • Flush water lines before patients are readmitted.
  • Thoroughly clean construction site after completion of work.
  • Move high risk patients who are in or adjacent to the construction area.
  • Route construction workers and material away from high-risk patients.
Class 4

In addition to Class III requirements,

  • Provide anteroom to work area enclosure. Provide workers with dust impervious coveralls to be removed on leaving work area, or thoroughly HEPA vacuum workers on leaving. Mandatory shoe covers and walk-off mats.
  • Infection Control to regularly inspect construction site to ensure all precautions are being followed.