Fonte (Source): Consulting-Specifying Engineer

Por (By): Christopher J. Stipe, PE, Graef-USA Inc., Milwaukee

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Indoor air quality in hospitals

Hospitals and health care facilities must comply with ASHRAE and other regulatory standards with respect to air change rates, humidity requirements, and pressurization. ASHRAE Standard 62.1 is the most commonly referenced standard to meet appropriate HVAC system design. Other factors to consider include the use of UV light to reduce hospital-acquired infections, unique air requirements, and outdoor air systems.

Learning objectives

• Understand what defines indoor air quality (IAQ).
• Learn why IAQ is an important factor in hospitals and health care facilities.
• Learn what methods may be employed to improve IAQ.

Indoor air quality (IAQ) encompasses a wide variety of factors: temperature, humidity, quantity, presence of chemicals and other contaminants, and the quality of outdoor air brought inside are typical metrics used to define IAQ. The concept of IAQ is especially important with regard to the environments within hospitals and other health care facilities. The patients within the facility and the staff caring for those patients are all directly impacted by the quality of air in the building. IAQ is also a component of sustainable concepts that are incorporated into the design of such facilities. Improved IAQ is a viable goal for overall improvements in building occupant satisfaction at hospitals and other health care facilities.

Patients are the sole reason hospitals and health care facilities are in business. Hospitals have been traced back as far as ancient Egypt and Greece, where temples to Asclepius—the Greek god of medicine, healing, rejuvenation, and physicians—were created to offer medical advice, discussion, understanding of afflictions, and methods to heal those afflictions. In fact, the “rod of Asclepius,” which is a staff with a snake wrapped around it, is still used as the symbol of medicine to this day. Patient safety and comfort are the top priority of any health care organization.

Medicare and Medicaid account for 55% of all care provided by hospitals, and nonprofit hospitals are required to accept Medicare and Medicaid reimbursement benefits. In 2008, the Centers for Medicare and Medicaid Services (CMS) refused to offer reimbursement for some nosocomial infections (infections that were acquired in a hospital), which had a direct impact on the finances of health care organizations. In 2012, they included additional nosocomial infections to the list of maladies that would not qualify for reimbursement. Patient comfort is reflected in hospital ratings such as Press Ganey Survey rankings and the Hospital Consumer Assessment of Health care Providers and Systems (HCAHPS). Such patient-satisfaction survey results also directly impact the funding CMS provides to health care organizations. As a result, hospitals and other health care facilities have focused on measures to reduce their nosocomial infections and increase patient comfort, with IAQ being one of the components.

The staff is just as important as patients to the viability of health care organizations. Staff for these organizations is comprised of the doctors, nurses, housekeeping, maintenance, administration, etc. The indoor environment impacts the productivity, morale, health, and welfare—and ultimately retention of a facility’s workforce. In a study by Lawrence Berkeley National Laboratory, for instance, they found that improved IAQ improves worker productivity by 0.5% to 5%—a national workforce impact of $20 billion to $200 billion. These impacts provide health care organizations the incentive to improve the environment for their workers, and once again IAQ is part of that equation.

Hospitals and health care facilities look to sustainable design concepts to reduce energy consumption and to generally try to represent good stewards of the environment. Additionally, several municipalities and other governmental agencies actually require U.S. Green Building Council LEED certification or LEED-equivalent design efforts for all buildings—including hospitals—under their jurisdictions. The 2003 Commercial Building Energy Consumption Survey (CBECS) identifies that hospitals spend 10 times more on energy use on a per-building basis than other building types—to the tune of $8.8 billion in energy costs per year. A figure this daunting provides a sizeable target for health care facilities to focus on to reduce costs. Anomalies in an updated CBECS in 2007 led to a revised study in 2012. The results of the 2012 CBECS are expected to be released at the end of 2015, but there certainly still are savings to be pursued.

Detriments to IAQ

To improve IAQ, engineers and designers must understand the components that can impact it. For health care facilities, these components typically fall into four major categories: the patients, the staff, the building, and the outdoor environment. By looking at each of these categories in depth, designers can develop methodology to ensure detriments to IAQ are addressed and minimized.

Patients may be one of the main reasons to improve IAQ, but they also are a considerable source of air contaminants. The patients are at these facilities because of various health concerns, which can include infections, viruses, and other diseases. Patient coughing can introduce contaminants into the air and onto adjacent surfaces. Bodily fluids as a result of wounds, infections, incontinence, and other reasons can be transferred from the patient to clothing, bedding, and other surfaces. Wounds and other infections and diseases, as well as various medical procedures, can introduce objectionable odors into the air.

Facility staff is typically in immediate contact with all of the contaminants identified as being generated by the patient. Hand-washing, the use of gloves, and the proper disposal of soiled gloves, bandages, and dressings are important components of a facility’s hygiene protocol that, when not followed, introduce the potential to spread the contaminants generated by the patient. A facility’s staff doesn’t just include those with direct patient interaction. Housekeeping employees responsible for keeping the building clean is another source of IAQ contaminants based on their methods and use of chemicals for cleaning and disinfecting. Carting of trash and other waste products can offer a source of particulate contamination to the air if the waste is not covered properly. The chemicals used for cleaning can introduce objectionable odors into the indoor environment. If the cleaned surfaces don’t dry properly, they can provide an opportunity for mold growth.

The building itself can offer other sources detrimental to good IAQ. The ductwork used to distribute air throughout the facility can become dirty over time and trap various contaminants such as dust, dirt, and even biological organisms. Moisture from HVAC humidification can condense within the duct system. Moisture can also seep into various building components from breaches in the building envelope, concealed leaks, or even overspray from the cleaning process. This moisture can instigate mold growth over time, which is often undetected until the problem becomes substantial. Even the transportation of dirty linens throughout the building can present a detriment to IAQ.

Outdoor air, on the surface, would hardly seem to be considered a potential detriment to IAQ. While outdoor air is introduced into buildings to freshen the IAQ, its ability to actually improve it is dependent on the conditions of the air and from where it is drawn. Vehicle traffic and emergency-generator exhaust are two very common contaminants that can be drawn in with the outdoor air. Keeping in mind that IAQ also comprises temperature and humidity, too much hot, humid air that exceeds the building’s air-handling systems’ capabilities to condition it will result in temperature and humidity within the building that are outside of the desired range. Insufficient (where not enough filtering is provided) or deficient (where filters have not been properly replaced when necessary) filtration within the air-handling systems also offer the opportunity for various contaminants to be distributed via the airstreams throughout the building.