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Research Project

HOME ASSESSMENTS FOR ENVIRONMENTAL TRIGGERS OF ASTHMA AND ALLERGIES

Susan Flappan CIH, Charles Barnes PhD, Adriana Frances MD,
Chitra Dinakar MD, Jay Portnoy MD

The Children’s Mercy Hospitals and Clinics
2401 Gillham Road
Kansas City, Missouri 64108

Background

Allergen avoidance is important to control environmentally triggered asthma. In 1997 the Allergy Section at Children’s Mercy Hospital (KCMO) set up a new program to evaluate exposures to asthma and allergy triggers inside the home. Medical personnel and environmental health specialists collaborated to implement this project, as part of the hospital’s comprehensive approach to managing asthmatic disease.

Methods:

The home allergen assessment consisted of collecting background information, visually inspecting the home for problem areas, and taking indoor air quality measurements.

Other similar cases have been reported, including a case study published in November 1999 in the National Institute of Environmental Health Sciences (NIEHS) journal Environmental Health Perspectives entitled Infant Pulmonary Hemorrhage in a Suburban Home with Water Damage and Mold (Stachybotrys atra). This case study was authored by MOLDetect’s Susan Flappan.

Results:

Homes surveyed represented a wide range of socioeconomic backgrounds and locations, but had one characteristic in common— at least one resident experienced significant respiratory ailments (e.g., asthma, chronic coughs, pneumonia, sinusitis, recurrent bronchitis, pulmonary fibrosis, idiopathic pulmonary hemorrhage). Seventy-eight percent of the homes reported major leaks, wet basements and/or prolonged wet carpeting on a written questionnaire. Thirty-eight percent of the homes had a relative humidity reading of 50% in one or more locations. Visual mold growth was frequently observed. The median airborne fungal counts in rooms patients likely spent a great deal of time, the family (television) room and patient’s bedroom, were 8,168 and 7,781 spores/ m3 respectively. The mean of the maximum count per home was 23,397spores/ m3. Twenty-three percent of the homes had at least one carbon dioxide reading greater than 1000 ppm and twenty-nine per cent had a relative humidity reading over 50%.

Conclusion:

Home environmental assessments should be regarded as valuable tools for the comprehensive management of asthmatic and allergic disease.

Keywords: Allergen avoidance, Environmental triggers, Home inspection, Asthma management, Indoor air quality, Stachybotrys, Mold growth

HOME ASSESSMENTS FOR ENVIRONMENTAL
TRIGGERS OF ASTHMA AND ALLERGIES

INTRODUCTION:

Despite medical advances regarding the pathogenesis and treatment of asthma, the prevalence and mortality of this ailment continue to be a public health problem
1. The Center for Disease Control (CDC) reported an estimated 17.3 million Americans have chronic asthma– a leading cause of school absenteeism and lost workdays
2. The direct medical costs of treating a patient with severe symptoms average $18,000 per year
3. Additional costs related to a diminished quality of life are not quantifiable. Much research has been dedicated to finding better methods to manage this widespread disease.

Though scientists don’t understand all the effects of black mold, Sidney Efross of the EPA in San Francisco says,”There’s probably nothing we can call a safe level” of Stachybotrys.

Allergen avoidance to minimize exposure to triggers is an important strategy to control environmentally induced asthma. Although it is sometimes difficult to achieve, it is effective without the side effects of medicine 4, 5. Furthermore, a small fraction of asthmatics are resistant to steroid treatment, the final and most potent choice of medicines available to control severe asthma episodes. For these steroid-resistant patients, environmental control is critical 6.

Successful avoidance of triggers requires awareness of what initiates or aggravates symptoms. If outdoor pollen or mold counts are elevated, many persons stay indoors as much as possible keeping windows and doors closed. However, indoor contaminants can also trigger symptoms. EPA studies have shown that indoor air is often five to 10 times more polluted than the air outside7. Additionally, Americans spend most of their time indoors2. With the increasing prevalence of asthma throughout the world associated with perennial, rather than seasonal symptoms, high levels of indoor allergens may play a large role in the asthma epidemic5.

Although all interior structures harbor allergens, the private home has been shown to have higher allergen content than public places. Thus, it is prudent to make the home a primary target for allergen avoidance measures 8. Many areas of the home are prone to allergen accumulation. For example, the bedroom can be a favorite habitat for dust mites, which flourish in mattresses, pillows, carpets, draperies and/or upholstered furniture1. Cockroach antigen is frequently found in kitchens or bathrooms. Animal dander from cats and dogs can be found in the soft furnishings throughout a home, even when a pet is not present8. Fungi are prone to inhabit areas with high moisture content and low light levels. These areas include bathrooms, crawl spaces, basements, improperly maintained humidifiers or air conditioning units, and damp fabrics. The interior building shell itself can support fungal growth if moisture is permitted to leak between walls 7.

When allergen triggers are identified, appropriate measures can be implemented to improve environmental conditions. The Allergy Section at Children’s Mercy Hospital developed the Home Allergen Assessment Program for this purpose. Results from the first eighty-nine homes surveyed are described in this report.

METHODS:

The Children’s Mercy Hospital Home Allergen Assessment was primarily initiated as a clinical program, not as a research program, in an effort to help alleviate the symptoms of patients with asthma and other chronic or severe respiratory ailments (e.g., sinusitis, bronchitis and rhinitis). It was internally funded.

The assessment procedure consisted of: a) gathering a subjective history of environmental conditions in the home and the health symptoms experienced; b) obtaining objective indoor air quality data; and c) professionally inspecting for conditions that might contribute to allergen production or buildup. Inspections were conducted by a Certified Industrial Hygienist with background in laboratory and environmental health medicine and also by the Laboratory Director of the Allergy Department. The Pediatrics Institutional Review Board of the University of Missouri, Kansas City, approved use of any data collected for research analysis and publication.

WRITTEN QUESTIONNAIRE

An adult occupant in each home was asked to fill out a 57-item questionnaire. This collected pertinent information on the demographics and history of the home. It also inquired about symptoms frequently experienced by family members, what the perceived triggering circumstances were, if these symptoms were more pronounced in specific locations in the home and if symptoms improved when away from the home. The questionnaire has been described previously9.

AIR SAMPLING FOR MICROBIALS

Indoor airborne fungal counts were assessed with the Allergenco MK-3, a volumetric spore trap10. Standard locations tested were: a) the patient’s bedroom; b) the family or television room; c) the basement; and d) any area suspect of contributing to symptoms, as determined by reviewing the questionnaire or talking with a member of the household. When possible, an outdoor sample was taken at the time of the investigation for use as a baseline comparison to help determine if indoor spores originated as a result of outdoor infiltration or indoor mold amplification.

Particulates from the air were drawn into the Allergenco MK-3 sampler (Allergenco, San Antonio, TX, USA) at a rate of 15 Liters per minute. The particles impacted onto a microscope slide coated with a thin layer of silicone grease forming a line of deposition called a trace. The slide was stained in the laboratory with Calberla’s (Allergon, Pharmacia, Kalamazoo, MI, USA) in glycerin jelly. Fungal spores were counted and identified to the genus level by personnel certified by the National Allergy Bureau for the identification of airborne spores. Raw counts were calculated into spores/ cubic meter; with a formula that incorporates the flow rate, the percentage of the trace read, the sampling period in minutes, and the raw count of the spores11.

SURFACE SAMPLES

Suspect mold growth or contamination on a surface was sampled with a piece of transparent cellophane tape, approximately 1-2 inches in length. The sticky side of the tape was lightly applied to the potentially contaminated item and then placed into a labeled zip-locked baggie for transport to the lab. At the lab, it was mounted onto a glass slide with a drop of Calberla’s stain for background and read microscopically. The sample was initially scanned under high power magnification (400X), followed by closer examination under 1000X magnification (oil immersion). Fungal spores observed in 30-50 fields (1000X) were classified into genera and given semi-quantitative designations according to the frequency observed11,12.

DUST SAMPLES FOR ALLERGEN IMMUNOASSAY

Dust samples were collected with a portable hand vacuum (Dirt Devil or Oreck). Items vacuumed included mattresses, carpeting and upholstered furniture in rooms most often used and in areas of concern. Oftentimes, basement dust was sampled. Contaminants located there might be dispersed to other parts of the home if they gained access to the central furnace and/ or duct work13.

The vacuumed dust sample was frozen at minus 20 degrees Centigrade until ready for processing. It was then thawed to room temperature and passed through a 50-mesh brass screen to remove large debris. The sieved sample was weighed and 500 mg of material utilized. This dust was suspended in 2.5 ml of 0.01M ammonium bicarbonate (pH 7.5) and extracted for 3 hours at 25 degrees Centigrade. The extract was then passed through a 5 micron Gelman filter and brought to a volume of 2.5 ml with water. An additional 2.5 ml of glycerol was added for a final solution of 0.1 gram of dust per milliliter.

Eight allergens were measured by inhibition enzyme immunoassay (EIA), as described by Barnes, et al14. The antigens tested included Alternaria alternata, Cladosporium herbarum and Aspergillus fumigatus and Penicillium ssp., Dermatophagoides farinae (Dust Mite), Canis familaris (Dog), Felis domesticus (cat) and Periplaneta americana (cockroach). Antigen-specific polyclonal rabbit antibodies and specific antigenic materials were produced in-house or purchased from Greer Laboratories (Lenoir, NC). The assays have a limit of detection of 0.01 mcg/gram of dust and a coefficient of variation between 9 to 28%.

VENTILATION CHECKS

Evaluation of the ventilation system included examination of several items. Carbon dioxide levels were measured with a TSI Q-Trak 8550 (TSI Inc., Minneapolis, MN, USA) to determine the adequacy of the air circulation. This instrument uses a non-dispersive infrared sensor capable of measuring CO2 levels from 0-5000 ppm, with a resolution of 1 ppm. Supply vents were checked for abnormal signs of dirt or mold growth. Furnace filters were inspected to find out if they were properly placed and maintained. The area surrounding the furnace was examined for abnormal moisture problems15,16.

RELATIVE HUMIDITY, TEMPERATURE READINGS

Relative humidity (RH) and temperature readings were also measured with the TSI Q-Trak 8550. The humidity sensor uses a thin-film capacitive sensor to measures RH in the 5 to 95% range, with a resolution of 0.1 %. The temperature sensor uses a thermistor with a measurable range between 32 and 122 degrees Fahrenheit (F) and a resolution of 0.1 degrees F.

CARBON MONOXIDE LEVELS

The AIM 450 Personal Carbon Monoxide Gas Monitor (Imaging and Sensing Technology, Horseheads, New York, USA) was used to detect carbon monoxide in the home, particularly next to gas-fired appliances. This direct reading instrument utilizes a hydrogen chloride electrochemical sensor having a range of 0-999 ppm, with a sensitivity of 1 ppm.

INTERIOR INSPECTION

Many areas throughout the home were examined for evidence of allergen reservoirs. The presence of pets was noted, as well as whether pets were allowed into the bedrooms. The inspector also checked the patient’s bedroom for the presence of dust-collectors, such as mini-blinds, drapes, carpeting, upholstered furniture or stuffed animals. Other relevant factors were noted, such as the presence of a cool mist humidifier or use of allergen-proof encasements on mattresses and pillows. Bathrooms were checked for a functioning exhaust fan or window to remove excess moisture. The clothes dryer was observed for proper venting to the outside. Odors in the home were noted, as well as signs of tobacco smoke. Indications of water damage such as water stains, peeling paint, bubbling floors, standing water or condensation were checked for on interior walls, floors, ceilings, and windows. Patches of visible mold growth and leaks were further investigated15, 16.

EXTERIOR CHECK

If the home had a rainwater penetration problem into the foundation or a damp crawl space, the exterior of the home was inspected for proper rainwater drainage17,18.

RESULTS:

This study evaluates data from eighty-nine homes within a 60-mile radius of Kansas City, Missouri, surveyed during the years 1997 to 1999. Forty-one percent of the homes were residences of patients from Children’s Mercy Hospital and Clinics. These subjects were referred internally. Twenty-five percent of the subjects were self-referred after learning of the Home Allergen Assessment Program from media reports (television, radio, newspapers). The remaining 34% of subjects were referred by outside sources (private physicians or friends). The homes surveyed were 75% self-owned, 19% rented and 6% government-subsidized. The mean age of the residences was 26.8 years (range 0-80 years) with an average occupancy of 3.7 people. Homes were primarily located in urban and suburban residential districts (73%); whereas 21% were described as inner-city dwellings; and 6% were rural. Of the 89 homes, 85% were cooled by central air conditioning, 10% utilized window units and 5% utilized fans. The most common type of heating delivery was forced air gas (97%), with occasional gas gravity (2%) and rare baseboard electric (1%). Eighty-one questionnaires were completed (91%) from the 89 total homes. A partial listing of responses concerning the resident’s evaluation of conditions within the home is included in table 1. Responses to questions regarding the presence of asthma triggers in the home are listed in table 2. Moldy environment was the most frequently reported trigger (44%). Additional questions regarding symptoms indicated 38% of respondents were better when away from the home, 33% felt the worst in winter, and 19% reported perennial symptoms.

Airborne mold count descriptive statistics are listed in Table 3. Because air quality problems are often localized, the maximum spore count in each home (rather than mean count per home) was examined to determine the likelihood that indoor mold amplification had occurred within the residence. The mean and median maximum spore count for the eighty-nine homes sampled was 23,397 spores/m3 (SD= 48,026) and 7,056 spores/ m3 respectively. The highest concentration of airborne mold in any location tested in our sample group was 344,000 spores/ m3, which was found in a wet basement (unfinished) with stored scraps of construction site sheetrock. Mean spore counts from the family (television) rooms and patient bedrooms were 8,168 and 7,781 spores per cubic meter respectively. Stachybotrys spores were found in the air samples of 25 residences (28%). The ratio of indoor to outdoor total spore counts was also evaluated as a tool for determining indoor fungal amplification. The range of these values is illustrated in figure 1.

Surface samples were taken from patches of visible mold, areas suspect of having mold contamination, settled surface dust, or ventilation registers. The most commonly seen fungal spores were from the genera Cladosporium and Aspergillus/ Penicillium. Periconia, Epicoccum, Alternaria, Pithomyces, Basidiospores, Rust and Smuts were seen less frequently. Stachybotrys spores were identified in surface samples in 31 of 89 case homes (35%).

Vacuumed dust samples were collected for allergen immunoassays in 40 (n= 89) homes. Levels greater than 0.01 micrograms of antigen per gram of dust were identified in the following percentages of homes: cat 85%; Cladosporium 69%; Penicillium 51%; Alternaria 48%; dog 43%; Dust Mite 33%; Aspergillus 28% and American Cockroach 26%.

Carbon dioxide measurements were found to be higher than the ASHRAE (American Society of Heating, Refrigerating, and Air Conditioning Engineers) Standard 62-1989 recommended limit of 1000 ppm in at least one area of the home in 23% of the cases19. Other common ventilation problems encountered included missing, rarely changed or improperly installed furnace filters; a clogged, improperly attached or displaced air conditioner hose; supply vents coated with visible mold growth or dust; and dirty or improperly installed ductwork.

Nine percent of the homes had a relative humidity equal to or greater than 60% in at least one part of the home. An additional twenty-nine per cent had RH readings over 50%. Average temperature in the homes was 75 degrees Fahrenheit.

Low levels (between 2-3 ppm) of carbon monoxide were detected in three homes surveyed. These findings were attributed to improperly vented kerosene heaters (2 cases) and being close to roads with heavy traffic (1 case).

Visual inspection of interior walls, windows, ceilings, floors, and bedroom contents often uncovered previously unrecognized problems. Visible fungal growth was very common in the homes surveyed, usually due to major plumbing, roof, or rainwater leaks. Occupants were usually cognizant of the mold growth, but oftentimes did not recognize its relevance to respiratory health.

The most common reasons for rainwater entry into a foundation or a damp crawl space were poor grading and/ or dysfunctional or absent guttering. Twenty-two percent of the residences had a crawl space. All of them showed signs of visible wood rot or had a strong musty odor. None of the crawl spaces had a polyethylene vapor barrier covering the soil. One crawl space did have a gravel cover, but this did not prevent wood rot from occurring on the structures above. Several homes had both a crawl space and basement, which were openly attached to one another.

DISCUSSION:

The Home Allergen Assessment Program was developed in 1997 to complement Children’s Mercy Hospital’s comprehensive health care plan for asthmatic and allergic patients. Originally offered as a service to CMH patients, the program became regionally recognized and now serves the greater community. Results from the first eighty-nine homes investigated in this innovative program are included in this paper.

Homes in our sample group were located in rural, small town, lakeside, urban, and suburban settings. The units were single or multi-family dwellings. They were rented, subsidized or self-owned. Thus, our sample group encompassed a wide assortment of residences in the Greater Kansas City area. In spite of the diversified classifications, the properties were not randomly selected. All the residences had one characteristic in common; there was at least one occupant present with respiratory ailments. Reasons for interest in the program included a desire to alleviate poorly controlled asthma or to learn if environmental controls could decrease dependence on medications. Often residents wanted to learn if recent or past water damage might be related to the onset or exacerbation of symptoms. Thus, all participants were motivated by health-related concerns.

Our home assessments began with a brief discussion about environmental health concerns and a quick tour of the layout of the home. This was followed by signing a voluntary consent form to do the evaluation and a request for pertinent background information utilizing a written questionnaire.

Indoor air quality questionnaires can serve many purposes during an investigation. They assist in defining a complaint area or analyzing patterns of when symptoms are most noticeable. They gather data for epidemiological studies15. Furthermore, they allow an investigator to convey sincerity in identifying unhealthy conditions16. Many times they prompt recollections of relevant occurrences. Our questionnaire was helpful in all of these ways.

Over one third of the participants in our study reported on the questionnaire that symptoms improved when away from the home. Many believed the onset of ailments began shortly after moving into the residence or following a specific incident in the home. These temporal associations suggested health symptoms might be attributed to environmental factors.

The most notable finding from our questionnaire, however, was the frequent incidence of moisture-related problems in the homes investigated. Seventy-eight percent of the residences reported major leaks, wet basements and/ or wet carpeting (damp for more than 24 hours). Moisture on walls or windows occurred in over a third of the homes, indicating these homes had problems with over-humidification and/ or temperature variations that resulted in abnormal condensation (figure 2). While a majority of residences reported some type of moisture problem (table 1), it is noteworthy that mold was the most frequently reported trigger in the data set (table 2).

Dampness has been reported to be common (20 to 50%) in modern homes20 and has been statistically associated with respiratory disease21-24. One study conducted on a cohort of 4,625 eight to twelve-year-old children living in six different U.S. cities showed a consistently strong correlation between home dampness and respiratory symptoms, as well as other non-chest illnesses. The odds ratio for mold was 1.27 to 2.12 and the ratio for dampness was 1.23 to 2.16, (after adjusting for smoking, age, gender, city of residence, and parental education)25. In a study conducted in Taipei, China, prevalence of respiratory symptoms was predictably higher in homes with dampness, with the adjusted odds ratio ranging from 1.37 for allergic rhinitis to 5.74 for cough26. In 1988, a group of Canadian researchers surveyed 13,500 families with elementary school-age children and learned that homes with reported dampness had a higher prevalence of respiratory symptoms, with an odds ratio of 1.32 for bronchitis and an odds ratio of 1.89 for cough. Thirty-eight percent of the participants in these Canadian studies reported mold or moisture problems27.

Mold growth can occur anywhere in the home but is especially prone to thrive in places where humidity levels are greater than 50% and light levels are low. Some major areas of concern are bathrooms and basements1. In our data set, unfinished basements showed relatively high spore counts, with mean values of 25,145 spores per cubic meter. Even if the occupants spent a minimal amount of time in the basement, contaminants located there could spread to other parts of the home by entering the central furnace system and traveling in ductwork. Thus, the residents might have exposure20. Recent literature emphasizes it is undesirable and inappropriate to see or smell mold in indoor environments12. When these observable signs of contamination are present, the cause of the moisture problems should be addressed before or at the same time as remediation. Serious mold problems may have occurred if there has been prolonged water damage to organic materials such as wood, jute-backed carpet, wallpaper, books, cardboard, cork, paper, wallboard or wicker baskets28. Familiarity with appropriate remedial procedures is critical to properly address problem areas rather than exacerbate them. The New York City Department of Health and the Environmental Protection Agency (EPA) have published guidelines for this purpose 29,30.

Microbial problems may exist without being visually observable or producing a noticeable musty smell. In these circumstances, air and surface dust samples can help to disclose more subtle situations. There are no regulations specifying acceptable levels of indoor airborne fungal counts. Thus, interpretation of air sampling results is complex and must take into consideration many factors. One important criterion is to examine how indoor counts compare to outdoor (background) counts (Figure 1) in both the total spore and specific genera categories. Sixty-one out of 89 residences had outdoor data. Out of these, 37 had ratios of less than 1.0, meaning the total outdoor count (sum of all spore types counted) was greater than the total indoor count (maximum value found per house)[figure 1]. However, this chart does not reflect ratios of each fungal genus. In general, when the counts for a specific genus are higher indoors than out, it is an indication of indoor mold amplification. Marker mold spores, like the genera Chaetomium, are not normally seen indoors unless there has been significant water damage. Identification of fungi capable of producing mycotoxins, such as Stachybotrys, Memnoniella, Trichoderma, or Fusarium, is notable and reason for concern. The presence of one of these mold types may prompt additional precautionary measures during clean-up procedures, although current recommendations suggest all molds be treated as equally capable of causing ill health effects 29. If the population in question is immunocompromised, immunosuppressed, or highly allergic, a lower tolerance limit is probable. These and many additional issues may be important to the interpretation of air sample results 12,31,32.

Current statistics published by the National Allergy Bureau for outdoor mold spore exposures state that levels below 6,499 spores/ m3 are low, between 6500 and 12,999 moderate, from 13,000 to 49,999 high and above 50,000 very high. These designations are based on outdoor samples taken throughout the country. They are not based on health effects33. Whether these categories also apply to indoor exposures has not been determined.

Air sampling is a major part of a home allergen assessment but only allows snapshot view of the particles in the air at the time of sampling. Intermittent or residual microbials may be present yet undetected during the brief time interval tested. Examination of settled surface dust provides additional information that can reveal sporadic or historical problems12.

Earlier literature reported Stachybotrys is uncommon (1-3%) in homes34,35. However, Stachybotrys mold spores were found in air and/or surface dust samples in 36 of the 89 homes surveyed (40%). The literature also states Stachybotrys spores are slimy and thus do not become easily aerosolized36. However, this spore type was found in the air samples of 25 residences or 69% of the Stachybotrys-positive homes, with concentrations ranging from 84 to 8,400 spores per m3. The arithmetic mean count of airborne Stachybotrys in locations where it was found was 1,145 spores /m3 and the median was 420 spores/ m3. Stachybotrys mold is sticky in wet environments; however it becomes powdery when dry and therefore more easily aerosolized37.

Although the prevalence of Stachybotrys was higher than expected, it is important to emphasize the residences in this data set were not randomly selected. All the homes were inspected because there was cause to suspect evident respiratory problems were environmentally related.

Many strains of Stachybotrys are capable of producing mycotoxins38. Health symptoms that have been connected to Stachybotrys mold exposures include upper and lower respiratory tract illnesses, acute pulmonary hemorrhage in infants, chronic fatigue, dermatitis, eye irritation and immune dysfunction39-42.

The immunoassay tests performed on vacuumed dust samples provided additional insight into other allergenic exposures in the home. Specifically, tests for cat and dog dander, dust mites, cockroaches, and several molds were performed. The data was helpful; however there were difficulties in interpreting results. The method used reports results in terms of micrograms of allergen per gram of dust, rather than concentration of allergen per area tested. Detection of high allergen concentrations might take on less significance if averaged over a large sample area. Additionally, there is a wide variety of susceptibility among sensitized individuals and very few normals have been established as a recommended target. A successful remediation should accomplish a 90 percent reduction in allergens5.

Carbon dioxide (CO216.

Carbon monoxide (CO) is another important indoor air quality parameter and testing for it should be part of any residential inspection. While this contaminant does not precipitate asthma or allergies, individuals with impaired lung functions (asthmatics) are much more vulnerable to the effects of this chemical asphyxiant. Residents may be exposed to carbon monoxide, a colorless, odorless gas, and not know it45. A by-product of incomplete combustion, carbon monoxide can cause fatigue at 10 ppm, impairment of visual acuity at 50 ppm, headache and irregular heart beat after 24 hours at 50 ppm, nausea and mental confusion after one hour at 500 ppm, and death after one hour at 1500 ppm16. Less than half of the residences surveyed reported having carbon monoxide detectors installed in their home even though this device could be life saving.

The American Society of Heating, Refrigerating, Air Conditioning Engineers (ASHRAE), an organization that issues indoor air quality guidelines, recommends maintaining a 30 to 60% relative humidity for optimal health and comfort16,19. Allergists, however, believe indoor relative humidity should remain below 50% to prevent mold growth and dust mite proliferation2. They recommend the use of air conditioners and/ or dehumidifiers when humidity is high to minimize moisture content of the air. Creating adverse conditions for moisture-dependant microbials makes it difficult for them to survive. Both ASHRAE and physicians agree that when relative humidity drops below 30%, mucous membrane (eyes, nose, throat) irritation may occur16.

Indoor temperature extremes are undesirable not only because they cause discomfort, but also because they promote condensation. Warm air retains moisture better than cold air. Thus, when warm, humid air hits a pocket of cold air, the relative humidity rises. While room relative humidity is a gauge of potential moisture problems, it is actually the moisture content of the air directly adjacent to a cold surface that determines whether condensation will occur. At 100% RH, the air is saturated with water vapor. The moisture condenses from a gas to a liquid state. This dampness promotes mold growth and dust mite proliferation, two allergens that commonly affect those with sensitivities. Temperature extremes may be the result of blocked, unconnected or poorly placed supply or return vents, a lack of adequate weatherization, or ventilation short-circuiting15.

The interior inspection assists in determining where and what to sample. It also helps to disclose problem areas occupants may not be aware of. General housekeeping practices can be observed, as well as unusual odors or circumstances. Significant issues not reported in the questionnaire may be discovered allowing a more accurate, comprehensive assessment of environmental concerns.

The exterior inspection helps to determine the cause(s) of abnormal rainwater entry into a basement or excess moisture problems in a crawl space. Gutters, downspouts, and splash blocks should be functional and grading should slope such that rainwater is channeled away from the home. Moisture-retaining debris, such as leaves, building materials, firewood, or vegetation overgrowth should not be adjacent to the building. The soil in a crawl space should be properly covered with a 6 mil polyethylene vapor barrier to minimize moisture evaporation and associated microbial growth on the underside of the home. Crawl spaces should be vented on opposite sides to prevent stagnant air from promoting growth of unwanted microorganisms17,18. Contaminants from the crawl space can find their way into the home via minute crevices or through a direct opening from a crawl space into an attached foundation.

The described home allergen assessment program was developed and implemented by the asthma case management team at Children’s Mercy Hospital (KCMO) with the collaborative expertise of both medical and environmental health (industrial hygiene) professionals. This pilot project helped identify environmental factors in the home that could contribute to asthma, allergies or other respiratory ailments. With the insight gained, appropriate recommendations could be made to improve the health of residents.39, 42 The Home Allergen Assessment program continues to be highly utilized by CMH patients and the Greater Kansas City community today.

CONCLUSION

Once allergen sensitivities are identified, it is helpful for physicians to determine clinical relevance in light of environmental exposures1,5. Allergists inquire about the home environment to gain insight into triggers encountered on a regular basis; however, the doctor may not always receive accurate information. A patient may not mention an incident that occurred long ago or seemed minor. They may not want to admit to a situation like allowing tobacco smoke in the home. They may be unaware of odors due to olfactory fatigue or blocked sinuses. If there were previous occupants in the home, they may have no knowledge of prior incidents leading to allergen production (e.g., previous water damage or pets).

An environmental assessment by a qualified professional provides objective data revealing actual conditions. With accurate information, problem situations can be addressed with specific solutions. If the circumstances leading to allergen accumulation are resolved and the reservoirs removed, environmental stimulants causing histamine release and inflammation decline. Studies show decreasing exposures to allergens leads to diminished severity and frequency of symptoms 4. Therefore, the residential environmental assessment should be regarded as a valuable tool for the comprehensive management of asthmatic disease.

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Table 1: Answers (partial) to questionnaire (N=89)

Moisture or humidity problems Major leaks, wet basement, or wet carpet
(>24hrs)
78%
Moisture on walls or windows 37%
Crawl space (no soil
vapor barrier)
22%
Perception of
air quality
Musty smell or
items, strange odors
67%
Drafts, cold and/or
hot pockets
49%
Staile air 29%
Dry Air 22%
Humid Air 15%
Patient bedroom Carpeting 77%
Stuffed animals
present
52%
Pets allowed in
bedroom
42%
Down comforter,
feather pillow, and/ or wool blanket
28%
Mattress encasement utilized 16%
Pillow encasements
utilized
13%
Cool mist
humidifiers (when sick)
9%
Potential
chemical/
Recent changes,
remodeling, new furniture
44%
particlate
exposures
Frequent use of
pesticides
25%
Resident works with
harmful chemicals or dusts
16%
Home hobby utilizes
chemicals, fumes, dusts
8%
Other
potential triggers
Pets 62%
Gas stove (nitrogen
dioxide)
35%
Tobacco smoke
allowed
15%
Ventilation Central a/c 85%
Disposable
fiberglass filter on HVAC system
75%
Fans utilized 57%
Central humidifier 52%
Miscellaneous Live by highway,
airport, garage, industry or business
29%
Carbon monoxide
detector in home
48%
Have known chemical
sensitivities
32%

Table 2: Reported Triggers (N=89)

Moldy Environments 44%
Extreme cold / hot
temp
33%
Windy conditions 27%
High pollen counts 41%
Emotional stress 28%
Strong smell 23%
Tobacco smoke 39%
Humidity 28%
Animals 20%
Bacterial/viral
infections
38%
Excercise 28%
Dryness 20%
Pollution 27%
Dusty conditions 34%
Pollution 27%
Perfumes 14%
Foods 11%
Finally a reliable mold test kit