Attention to indoor air quality is particularly important in health care settings for several reasons.  First, because many patients have infections that can spread through airborne exposure, proper ventilation must be maintained.  Second, because the density of people in health care settings is relatively high, reducing contact through droplet nuclei exposure is of considerable concern in controlling the spread of infection.  Third, many hospitals are aging and their ventilation systems are in serious need of maintenance and repair.  

 The US Environmental Protection Agency (EPA) recently called Indoor Air Quality (IAQ) one of the most important environmental health problems in the 1990s.  IAQ problems generally are caused by two circumstances: (1) poor or inadequate ventilation and (2) exposure to one or more contaminant sources in the building.  

In one major CDC study of hospitals, post-surgical infection rates were between 1.5 and 3 percent.  Infection rates will probably not decline significantly from these rates, as a result of improvements in disinfection and sterilization techniques.  What might greatly reduce infection rates, however, would be a reduction in microbe concentrations in hospital air.  This is an area that deserves, and is beginning to receive, the attention it demands.  A reported incident of an influenza epidemic among airline passengers demonstrates the case with which infections can be spread through contaminated air.

 OSHA says that "the most effective way to prevent or lessen transmission" of nosocomial infection is to isolate the airborne contaminant and to provide an environment that will promote reduced exposure to the contaminant. 

Allergens are normally harmless substances that can cause a reaction in sensitive people. Health care facilities harbor many allergens, but documentation of nosocomial outbreaks is rare. Environmentally related allergic reactions depend upon these three interactive elements:

·         Exposure to the allergen; 

·         Individual susceptibility; and 

·         Length of time exposed. 

Symptoms of allergic reactions such as runny nose, sneezing, coughing, and itching and watery eyes may be attributed to other diseases or conditions. It is suspected that sensitive, exposed patients are frequently discharged before an accurate diagnosis is made.

The most common microorganisms that cause allergenic reactions are environmental molds and bacteria. Molds can be found in damp spots such as shower stalls, water-stained ceiling tiles, mattresses, and foam rubber pillows. The spores become important only if they become airborne. 

The National Institute of Occupational Safety and Health reports a high level of both molds and bacteria, especially bacillus species in air samples taken from health care facilities. Fibrous insulation materials taken from air ducts where allergic complaints have been identified have also been documented.

The primary business of health care facilities is to provide patient care. The very nature of this business can expose both patients and employees to more infectious, allergenic and other pollutants than people are exposed to in non-health care settings. The impact of airborne pollutants on patients differs from the impact on employees in several areas:

·         Patients are at greater risk because their underlying illness or condition renders them susceptible to diseases that may not affect a normally well person. 

·         Patients are at greater risk to pollutants because normal host defenses have been breached by procedures and treatment that leave them more vulnerable to attack. 

·         Patients have increasingly shorter lengths of stay, thus reducing exposure time to pollutants. 

·         Patients are not usually exposed to cleaning, disinfecting, preserving, and other substances used to maintain the physical plant and equipment.

Airborne fungi are common and for most individuals breathing ambient concentrations of airborne fungi results in no adverse effects on health. However, hospitalized patients with immune suppression are susceptible to infections from naturally occurring airborne fungi that can grow at body temperatures. The incidence of infections caused by fungi that were once considered only saprophytic has risen dramatically in recent years. The increased use of antibiotics and chemotherapy has contributed to this trend as have the advent of routine organ transplants, the introduction of methods for advanced life support and the management of newer diseases such as AIDS.

The most common genus of fungi responsible for opportunistic infection is Aspergillus. Other genera known to occur as pathogens includes Acremonium, Beauveria, Chrysosporium,

Fusarium, Mucor, Paecilomyces, Penicillium, Scedosporium, Scopulariopsis and Trichoderma among others.

Aspergillus

Common environmental microbes such as Legionella and Aspergillus present big problems in hospitals because many diseases and treatments leave patients vulnerable to the illnesses they cause. A mold like Aspergillus, for example, can grow on modern building materials such as gypsum board and ceiling tile if they are allowed to stay wet more than 72 hours.

A major source of indoor air pollution for hospitals results from construction and renovation. During these activities, large amounts of dust, which can contain harmful aerosols, can be released and can migrate throughout a building if not contained. The microbes can become airborne when their growth areas are disturbed during construction, renovation or repair, or when water is sprayed into the air. Although many people breathe these airborne spores only those who are susceptible will become infected with the illnesses, which are very difficult to diagnose and treat.  Aspergillus spores range in size from 1.5 um to 6 um.

The greatest problem, however, is the association of construction with infectious disease caused by the release of opportunistic fungi such as Aspergillus fumigatus. The disruption of the loci of growth or accumulation will release the spores enabling them to travel with the air currents in a building unless contained. Even when excavation occurs outside of a hospital, spores can enter through poorly sealed windows or around improperly installed filters.

The Aspergillus genus has been divided into 18 groups.  While most Aspergillus are found in the outdoor environment, several have been implicated in systemic, pulmonary, subcutaneous, cutaneous, nail and ear infections.  Some strains of Aspergillus can produce toxins and may cause allergic reactions such as allergic rhinitis, allergic sinusitis, and allergic asthma.  If occurring as a reservoir in indoor environment, they can cause asthma and hypersensitivity pneumonitis.  They may be isolated from the air and grow well on many materials and organic debris.  These species of moulds are xerophiles and can withstand very warm temperatures and extremely dry atmospheres.  Animals and birds are frequently infected.  

The types of diseases caused by Aspergillus are varied, ranging from an “allergy”-type illness to life-threatening generalized infections. Diseases caused by Aspergillus are called aspergillosis. The severity of aspergillosis is determined by various factors but one of the most important is the state of the immune system of the person.

Aspergillosis is acquired by inhalation of airborne dust particles that carry the spores. Pneumonia develops and the fungus disseminates through the blood stream to other organs. Mortality rates have been reported as high as:

·         95% in bone marrow transplant patients;

·         13-80%in leukemia patients; and 

·         8-30%in kidney transplant patients. 

Construction management is crucial to fungal contamination prevention.  One large transplant referral HMO found that the mortality rate in liver patients declined from a probable 13% to no documented cases the next year when the patients were sent from a health care facility undergoing renovation to a facility where no construction and renovation was taking place. Another tertiary care center noted a reduction from a 9% rate in aspergillosis to no documented cases the following year after the development and enforcement of an extensive dust containment policy during construction and renovation, which included inspections by the infection control team and serious fines for noncompliant contractors.

However, despite the use of anti-fungal drugs, the outcome of transplant patients with aspergillosis continues to be grim, due to the underlying disease or condition and the therapy given to induce immunosuppression as a means to prevent rejection of the transplanted organ.

REASONS FOR SAMPLING ASPERGILLUS

·         Environment of Careâ Essentials for Health Care, JCAHO, 2001; EC.1.7 (a);(g)(3)

·         Managing Utilities; Monitoring and Inspection Activities (pg. 54-55).

·         ASHRAE Standard 62-1989 and Standard 55-1992.

·         Bioaerosols:  Assessment and Control, ACGIH, 1999.

Building Investigations/IAQ Surveys

A walk-through inspection of the building is performed and indicator IAQ parameters are measured and recorded.  An initial walkthrough of the problem area provides information about all four of the basic factors influencing indoor air quality (occupants, HVAC system, pollutant pathways, and contaminant sources).

Direct reading instrumentation is used to determine these indoor air quality parameters such as carbon monoxide (CO), carbon dioxide (CO₂), temperature (°F), and relative humidity (RH).  Samples for bioaerosol (airborne fungus and bacteria) contamination are taken to both quantify and qualify any airborne mold, fungus, or bacteria present.  Impactor instrumentation is used to collect the bioaerosol samples.  This type of instrument impacts particles on agar media to provide information on cultivable (“viable”) propagules (spores or hyphal fragments capable of producing a colony).  Other indoor contaminants can be sampled such as volatile organic compounds (VOCs), formaldehyde, and total and respirable dust.    

Currently, measurements of fungal exposure rely on air sampling for culturable fungi or total spore counts.  In addition to air sampling, assessing indoor fungal contamination requires careful review of the building history and visual inspection by an experienced environmental professional.   

Source or bulk sampling is taken if needed.  Fungi do not grow in the air, but originate on surfaces or in substrates.  Many building materials, such as ceiling tiles, wallboard, wallpaper, and soiled fiberglass insulation, are well known substrates for fungal growth.  Elevated fungal levels dominated by one or two fungal types are often indications of fungal amplification.

Because there are generally no accepted guidelines or standards for fungal bioaerosols, comparative sampling becomes necessary.  Usually outdoor samples and samples taken from a non-problem location are collected as a reference for comparison

Results of bulk samples give strong indications as to whether a sample is contaminated or not.  A contaminated sample often results in a pure culture or a mixture of no more than two to three fungi.  A high fungal level dominated by one or two fungi is suggestive of fungal amplification in situ.  Contaminated materials or surfaces can then be removed or disinfected.

A comprehensive sampling should include air sampling as well as source sampling.  Results of air sampling provide an estimate of possible human exposure and an indication of possible indoor contamination.  However, air samples may often give false negative results.  Only a thorough inspection and analytical confirmation can ascertain whether there is fungal contamination in a building.

For more information, contact

Alan L. Wozniak, CIAQP

(800) 422-7873 ext. 802

info@pureaircontrols.com