IAQ in Hospitals: CDC Guidelines Part 1
Indoor air quality is a concern in any commercial environment but it is particularly significant in hospitals and other healthcare facilities where the spread of environmental and airborne pathogens can have particularly serious consequences. According to reports from the Center for Disease Control (CDC) and others, nosocomial infections (also known as Healthcare Acquired Infections – or HAI) are on the rise.
While poor indoor air quality (IAQ) issues represent only a portion of the total circumstances leading to HAI, the detrimental effects that it can have on both patients and healthcare workers can not be underestimated. The CDC, therefore, has developed guidelines for minimizing healthcare-associated infections that include ventilation standards for specialized care environments such as isolation rooms, protective environments and operating rooms. The original report, Guidelines for Environmental Infection Control in Health-Care Facilities, includes recommendations for reducing the spread of contaminants via water, services and other environmental factors and comes in two parts.
The first part looks at general guidelines as they pertain to day-to-day HVAC functioning. Here are some of the recommendations I think are particularly noteworthy:
- Use AIA guidelines as minimum standards where state or local regulations are not in place for design and construction of ventilation systems in new or renovated health-care facilities. Ensure that existing structures continue to meet the specifications in effect at the time of construction.
- Ensure that heating, ventilation, air conditioning (HVAC) filters are properly installed and maintained to prevent air leakages and dust overloads.
- Engineer humidity controls into the HVAC system and monitor the controls to ensure adequate moisture removal.
- Locate duct humidifiers upstream from the final filters. Incorporate a water-removal mechanism into the system and locate all duct takeoffs sufficiently downstream from the humidifier so that moisture is completely absorbed.
- Incorporate steam humidifiers, if possible, to reduce potential for microbial proliferation within the system, and avoid use of cool-mist humidifiers.
- Locate exhaust outlets >25 ft from air-intake systems. Locate outdoor air intakes >6 ft above ground or >3 ft above roof level. Locate exhaust outlets from contaminated areas above roof level to minimize recirculation of exhausted air.
- Use portable, industrial-grade HEPA filter units capable of filtration rates in the range of 300--800 ft3/min to augment removal of respirable particles as needed.
- Select portable HEPA filters that can recirculate all or nearly all of the room air and provide the equivalent of >12 ACH.
- When ultraviolet germicidal irradiation (UVGI) is used as a supplemental engineering control, install fixtures 1) on the wall near the ceiling or suspended from the ceiling as an upper air unit; 2) in the air-return duct of an AII area; or 3) in designated enclosed areas or booths for sputum induction.
- Seal windows in buildings with centralized HVAC systems, including PE areas.
- Emphasize restoration of appropriate air quality and ventilation conditions in AII rooms, PE rooms, operating rooms, emergency departments, and intensive care units.
- Provide backup emergency power and air-handling and pressurization systems to maintain filtration, constant ACH, and pressure differentials in PE rooms, AII rooms, operating rooms, and other critical-care areas.
- HVAC systems serving offices and administrative areas may be shut down for energy conservation purposes, but the shutdown must not alter or adversely affect pressure differentials maintained in laboratories or critical-care areas with specific ventilation requirements (i.e., PE rooms, AII rooms, operating rooms).
- Whenever feasible, design and install fixed backup ventilation systems for new or renovated construction of PE rooms, AII rooms, operating rooms, and other critical-care areas identified by ICRA .
These are just some of the recommendations associated with proper HVAC functioning in this particularly sensitive environment. The CDC report also offers recommendations for ensuring critical IAQ levels during construction and remediation projects. I’ll review some of those in an upcoming post here on Proud Green Building.
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