Healthcare facilities, such as hospitals, have to pay particular care to indoor air concerns. Many of those who are susceptible to these problems may be patients such as people with pre-existing health problems, the frail elderly, people with cancer who are going through treatment, and those who may have depressed immune systems. Some hospitals also have special units that need particular care in terms of indoor air quality such as bone marrow units, neonatal intensive care units, and burn units. In addition to having people inside the building who are at risk to these problems, there are some unique indoor air concerns in healthcare facilities including those usually found in buildings. These include:
Biological contaminants such as bacteria, mold, and viruses can breed in stagnant water that has gradually accumulated in ducts, humidifiers and drain pans of the ventilation system; or water that has collected on ceiling tiles, carpeting, or insulation. This is particularly a problem in older buildings that may have broken fans or other maintenance problems. Such maintenance problems may be common since many healthcare facilities are always looking for ways to save money.1 All parts of the humidification and dehumidification systems must be kept clean and dry to prevent growth of bacteria and fungi. Otherwise, microorganisms, such as Aspergillus spores, can become airborne and infect patients who have suppressed immune systems. Moisture in other areas may also contribute to the growth of mold from increased humidity. For example, certain respiratory care equipment produces a lot of mist, which can increase the humidity levels in a room. These rooms need to be cleaned particularly well to prevent the growth of mold.
Hospitals have to take special precautions to prevent infections from spreading. As it is, 5% of all patients who go to hospitals for treatment will develop an infection while they are there.2 However, it is not only patients or residents in these facilities who are at risk. Healthcare workers have a higher risk than most people of being infected by airborne or bloodborne diseases. For example, healthcare workers who work at facilities in cities have positive tuberculosis (TB) skin tests (meaning they have been exposed to the TB bacteria) about eight times more often than the rest of the US population. In addition, at least 17 healthcare workers have developed drug-resistant TB as a result of working in these environments.3
Because patients have infections that can spread through the air, there must be proper ventilation. In the case of airborne infectious diseases like TB, patients are often kept in special isolation rooms that are under negative pressure so that contaminated air will not get out of the room. This type of isolation is called infectious isolation. However, often people who may be infectious may not be diagnosed right away so those in emergency rooms (ER) are most at risk.
To minimize this risk, some hospitals are taking steps to design their facilities to try to prevent the spread of infectious diseases in the ER. For example, when the Children's Hospital in Fort Worth, Texas redesigned their ER in 1996, they had the rooms designed to decrease the chance of airborne transmission of diseases. To begin with, they designed the waiting room where the air swept through the room and decreased the chances of any mixing of the room air. If somebody has an infectious disease that gets into the air and there is mixing of the room air, there is a good chance that others in the room will also breathe in that infected air. Once the air passes through the waiting room to the return air duct, it passes through a HEPA filter. These filters trap particles bigger than 0.3 m (micrometers) in diameter. Most bacteria are 0.5 to 10 um and TB is 1 to 5 so these filters should capture any infectious organisms in the air. By using the HEPA filter in the return duct, the hospital saves money by not having to have the room totally exhausted to the outside since this is not a high-risk area. If there are patients who come in who have signs or symptoms of an infectious disease, they are put in a separate room that does have 100% exhaust to the outside so there is no chance of the air returning to the hospital. These rooms can also be put under negative pressure so infected air from inside of them won't get out into spaces like hallways.4
For high-risk patients, like those whose immune systems are compromised, there may be special rooms that are under positive pressure in which fresh air flows into the room and there is positive pressure built up so that no contaminants can come in from the outside. These rooms are called protective isolation rooms since they are designed to protect the patient. One important contaminant in the air that these at risk patients are being protected from is fungi.
One researcher calculated that about 9% of reported hospital infections between 1986 and 1990 were caused by fungi.5 However, for these rooms to be effective in preventing infections like this, it is very important that the air filters in the ventilation system be changed often. That is because filters are an ideal location for fungus to grow. In one study, nine of 11 air filters that had been in use less than 1 month showed fungal growth on them. These filters had been taken from different air handling units on different dates. The two filters that did not have growth on them had been treated with an antimicrobial agent; however, the untreated cardboard frames around the filter media had extensive fungal growth.6 One bone marrow unit learned the hard way about the importance of cleaning filters when a 6-year-old patient developed pneumonitis and died. The child's autopsy showed that the child had been infected with Aspergillus fumigatus. When investigators found that staff on the unit were also suffering some health problems, they inspected the air filters on the bone marrow unit, which were found to be completely clogged with high levels of Aspergillus fumigatus.7
Just like in other buildings there can be many chemical hazards such as volatile organic compounds from adhesives, furnishings, manufactured wood products, copy machines, pesticides, cleaning agents, and tobacco smoke. Contaminants from the outside such as motor vehicle exhaust can get into the ventilation system. To prevent the spread of infections, housekeeping staff often use cleaning chemicals such as disinfectants to help keep the healthcare facilities clean. In addition, since patients are sleeping in hospitals and nursing facilities at night, cleaning is often done during the day, which means more people may be exposed to the vapors from the chemicals. However, hospitals also have unusual chemical hazards also. For example, some lab tests in healthcare facilities require the use of solvents such as acetone, benzene, formaldehyde, xylenes, methylene chloride, and toluene.
There are also chemicals used to disinfect medical equipment such as glutaraldehyde and ethylene oxide (which can cause cancer). Glutaraldehyde is a common contributor to IAQ problems. Though there are standards saying what levels of exposure should be safe for this chemical, some people have reactions at low levels. That is what happened in the endoscopy unit at one hospital. Though air monitoring showed that the levels should have been at concentrations considered safe, some of the people working there were still having problems. Investigators recommended additional exhaust ventilation and eye and face protection for employees who work with the solution.1
Certain drugs that can accidentally get into the air, such as anesthetic gases from operating rooms, can also be hazardous. One anesthetic gas, nitrous oxide (often found in some dental offices), has been linked to spontaneous abortions in female staff who are continuously exposed to it. Other drugs can be quite toxic and require special ventilation. One example is aerosolized medications like pentamidine, which may be given for conditions like pneumonia associated with AIDS. ASHRAE requires that these treatments must be given in rooms with increased ventilation. Certain chemotherapy drugs used to fight cancer are also very toxic and need to be prevented from getting into the air.
Latex gloves, which first became very common in hospitals in the 1980s with the increase in AIDS, HIV, and other bloodborne diseases, began causing latex allergies in healthcare workers. The main problem was not so much the latex in the glove itself, but the powder. The latex protein molecules can bind with the cornstarch powder on the outside and inside of gloves. The powder on the outside keeps them from getting stuck to each other in the box and the powder on the inside of the gloves makes them easier to put on. When gloves are pulled out of the box, some of the powder with the latex molecules gets into the air as it does when gloves are removed. Once in the air, the latex dust can float and be inhaled by people within a large area, putting them at risk of an allergic reaction.
A growing number of healthcare workers, as well as the public at large, have latex allergies. This can result in health problems ranging from skin irritations to potentially fatal breathing problems. Estimates indicate that up to 6% of the general population and 10% or more of healthcare workers have latex allergies.8,9 Consequently, many hospitals have been changing over to using non-latex sterile gloves like nitrile. However, latex is found almost everywhere. One of the newest prohibitions in "latex-safe" hospitals has been to prohibit latex balloons. Originally, latex balloons were banned only in many children's hospitals because they shrunk when deflated and could possibly be swallowed. It is only in the past couple of years that hospitals have begun banning latex balloons. That is because latex balloons are some of the most allergenic latex products made and these allergens can get into the air. Instead, hospitals recommend mylar balloons. These are the ones with the shiny, metallic look. Though mylar balloons can cost anywhere from 2-5 times more than latex balloons, they last much longer, have messages printed on them, and do not cause reactions in people allergic to latex.10
Many long-term care facilities use carpeting. To help the carpeting last as long as possible, these facilities should work with a cleaning service in setting up a routine maintenance program to prevent problems before they occur. Though this may cost money in the short term, it saves money in the long term by not having to replace the carpet as often. However, they need to do their homework to find out what preventive care the flooring will need ahead of time so that businesses will not take advantage. One healthcare facility had been told by one company that they would have to strip and refinish their floors every two weeks. With proper routine maintenance, stripping may not be required for years at a time!11 Though manufacturers are producing carpeting that is easier to clean, it still needs to be kept clean and dry to prevent mold and mildew from triggering allergic reactions. It is also good to use cleaning methods that avoid putting a lot of moisture into the carpeting. If a cleaning service is coming in, their workers should have been trained about any chemicals they use so they do not overuse them.11
One of the best ways to improve indoor air in a healthcare facility is to purchase environmentally friendly products that do not contribute to indoor air pollution. For example, Kaiser Permanente no longer buys mercury thermometers or mercury blood pressure equipment. Hartford Hospital also decided to switch over to mercury-free, latex-free blood pressure equipment, which has meant fewer mercury spills. This translates into a savings since there are no longer the associated cleanup costs.12 There is also no longer the risk of the toxic exposure of people to the mercury. Other healthcare facilities have all stopped using mercury-containing products unless there are no reasonable alternatives available. Some healthcare facilities have also begun recycling their fluorescent lights and have switched most routine glove purchases from latex to nitrile gloves. Hospitals may also buy recycled solvents for their laboratories instead of brand new ones.12
To find out more about healthier alternatives for hospitals, consult the following resources:
The purpose of ventilation is to assist in providing a safe, comfortable and healthy environment for the patients and staff in a healthcare facility. In Europe, the trend is toward more natural ventilation, with windows that open. In the U.S. if a hospital is mechanically ventilated, it must be with 100% outside air. How much air and how clean depends on the part of the hospital. For example, operating rooms require 30 cfm per person according to the ASHRAE requirements for healthcare facilities. In addition, HEPA-filters and ultraviolet germicidal irradiation lights may be used since there are often large open wounds exposed for long periods.13
ASHRAE has a handbook that gives specific ventilation requirements for different parts of the hospital. For example, they have specific requirements for ventilation and filtration to dilute and remove contamination such as airborne microorganisms and viruses, hazardous chemicals, and radioactive substances. ASHRAE has also specified the need to restrict air movement in and between the various departments and gives different temperature and humidity requirements.
There also needs to be special precautions if construction is being done in healthcare facilities. For example, there should be dust-tight barriers and negative pressure in the area being worked on so that contaminants do not spread to other parts of the building.
Source: Aerias: Better Heath Through Indoor Air Quality Awareness
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