Airborne Fel Research Articles

Does Air Filtration Work for Cat Allergen Exposure?

The goal of this review is to compress all important information and results of the research in reducing cat allergen exposure using air filtration. Fel d 1 is the major allergen responsible for IgE responses in 90 to 95% of patients with cat allergy. Reduction of cat allergen in indoor air with different air filtration systems and portable devices has been demonstrated in the majority of the studies. Recently, early and late asthmatic responses were significantly reduced using portable HEPA air cleaners in an environmental exposure chamber. This review provides a comprehensive overview of the current state of airborne Fel d 1 air filtration targeting the most efficient devices in cat allergen reduction. Novel emerging HEPA filters are targeting reduction of cat indoor asthma trigger so patient can might benefit from efficient solution.

Cat (Fel d 1) and dog (Can f 1) allergen levels in cars, dwellings and schools.

Pets are an important source of indoor allergens. The aim of the study was to compare cat and dog allergen levels in cars, schools and homes. The study was carried out in 17 cars, 14 classrooms and 19 dwellings located in the highly industrialized and urbanized region of Poland. Dust and air samples were analyzed for Fel d 1 and Can f 1 using a double monoclonal ELISA assay. The highest amounts of cat and dog allergens (Fel d 1: 1169 μg/g; Can f 1: 277 μg/g) were found in dwellings with pets. Allergen concentrations were correlated with the number of animals kept at home. Although concentrations on automobile seats were lower, Fel d 1 levels exceeded 8 μg/g in 23.5 % of cars and high levels of Can f 1 (>10 μg/g) were found in 17.6 % of cars. The study revealed that cars of pet owners may be reservoirs of cat and dog allergens even when animals are not transported in them. In schools, concentrations of pet allergens did not reach high levels, but the moderate levels of Fel d 1 (≥1–8 μg/g) and Can f 1 (≥2–10 μg/g) were detected in 42.9 and 7.1 % of the investigated classrooms. Concentrations of cat and dog allergen in schools were higher than in homes without pets. While airborne Fel d 1 and Can f 1 levels were found low, residential allergen concentrations in settled dust and air were correlated. The study results suggest that classrooms and cars of pet owners may be important sites of exposure to cat and dog allergens, though the highest concentrations of Fel d 1 and Can f 1 are found in homes of pet owners.

Control of Airborne and Liquid-borne Fungal and Pet Allergens Using Microwave Irradiation

In this study, the dog, cat allergens (Can f 1 and Fel d 1) and fungal allergens (Alt a 1 and Asp f 1) were aerosolized and exposed to the microwave irradiation (2450 MHz) at different output powers for up to 2 min. The allergen bioaerosols were collected by a BioSampler, and analyzed using enzyme-linked immunosorbent assay (ELISA). Control and microwave-irradiated Asp f 1 allergens were also tested with IgEs in human blood sera samples. For airborne Asp f 1 and Alt a 1 allergens, the allergenicity was shown to decrease about 50% when exposed to microwave irradiation at 385 and 119 W and relatively no change at 700 W. For airborne Can f 1 allergen, the allergenicity was shown to increase about 70% when exposed to the irradiation at 385 W, but remained relatively unchanged at 700 and 119 W. In contrast, airborne Fel d 1 allergen was observed to lose allergenicity completely at 700 W, and retained about 40% and 80% at 385 and 119 W, respectively. Radioallergosorbent (RAST) tests showed that changes detected in IgE levels in human blood sera mixtures were not statistically significant for the control and microwave-irradiated waterborne Asp f 1 allergens. This study implies that although certain allergenicity reductions were observed for some allergens in certain cases, particular care should be taken when the microwave irradiation is used to disinfect food, water, and air because of its complex effects.

The Mass of Cat Dander Aerosolized is a Good Predictor of the Real-Time Airborne Fel d 1 Concentration in an Environmental Exposure Chamber (EEC)

RATIONALE: Currently, the only method for a quantitative measure of airborne allergen level in an Environmental Exposure Chamber (EEC) is by ELISA. However, it is not a real-time measure. This study examines whether the grams of cat dander aerosolized per hour in the EEC correlate with airborne Fel d 1 concentration measured by ELISA. If so, mass of cat dander aerosolized could be used as a real-time estimate of airborne Fel d 1 allergen in the EEC.

An Aerosolized Cat Allergen Environmental Exposure Chamber (EEC) Model to Study Cat Allergic Patients: Assessment of Airborne Fel d 1 Concentration in Real-time ensures Controlled Patient Exposure to Cat Allergen

RATIONALE: The aim of this study was to examine whether real-time laser particle counts would correlate with airborne Fel d 1 concentration within the EEC, thus providing a feedback measure towards the maintenance of consistent levels of cat allergen over the course of patient exposure in the EEC. METHODS: Particle counts and size distribution were measured in real-time in our aerosolized cat dander EEC using an airborne laser particle counter (Lasair II, Particle Measuring Systems). Air samples were measured for airborne Fel d 1 concentration using an ELISA. The correlation between allergen concentration and particle size and number was assessed by Pearson Correlation analyses. RESULTS: Airborne Fel d 1 concentration was tightly controlled and ranged between 17 - 102 ng/m3 with an average of 37.30 ± 1.78 (SE) ng/m3. Fel d 1 concentrations were highly correlated with particle size and number, with the degree of correlation increasing with increasing particle size to a maximum correlation observed for 5-10 micron particles (r = 0.83). Relatively few particles greater than 25 microns were aerosolized resulting in the weakest correlation (r = 0.75). CONCLUSIONS: Airborne Fel d 1 concentration is highly correlated with particle counts, particularly for the largest particles effectively aerosolized indicating that they have the highest allergen content. Particle counts can be used as a real-time measure to help maintain the cat allergen within tight limits in the EEC and ensure controlled exposures to cat allergic patients.

Sublingual immunotherapy with a standardized cat dander extract: evaluation of efficacy in a double blind placebo controlled study

Little information is available on the clinical efficacy of sublingual immunotherapy (SLIT) using extracts derived from mammalian epithelia. To assess clinical efficacy of cat SLIT based on natural exposure challenge test (NCT). Fifty cat allergic patients with rhinoconjunctivitis with or without asthma were included in a randomized double blind placebo controlled clinical trial of cat SLIT during 1 year. Twenty-five patients received active treatment and 25 placebo. Sublingual immunotherapy efficacy was assessed by natural exposure challenge to a cat in a cat-room and by skin tests. Airborne Fel d 1 levels, symptom scores and peak expiratory flow (PEF) values were monitored. Thirty-three (66%) out of 50 patients completed the treatment. Fel d 1 content of the maximum concentration was 0.51 microg per ml. During the build up phase, the accumulated dose was 1.7 mug of Fel d 1 and during the entire length of the study was 17.1. No adverse reports were reported. The active group showed a marked reduction (62%) in symptoms during the NCT (P < 0.001) with no changes in placebo group. Active group also showed a reduced PEF response to cat exposure (P < 0.05), and an improvement in skin test reactivity to a standardized cat extract (P < 0.05), without significant changes in placebo group. Mean Fel d 1 exposure during the NCT was 6.2 +/- 2.21 ng/m(3). The results suggest that the cat SLIT used in this study was able to improve cat allergy based on natural exposure challenge.

Advances in environmental and occupational disorders 2006

In 2006, there continued to be significant contributions to the Journal in the area of environmental and occupational allergy. In addition to very strong clinical observations, there were a number of studies that examined the effect of environmental agents on cellular and molecular processes in allergy, and molecular approaches were also used in investigations of allergen structure and biology. The Journal also received a number of very strong epidemiologic studies examining several aspects of environmental and occupational allergy. Thus, this particular area of our specialty thrives as a result of clinical, mechanistic, epidemiologic, and translational observations. This article reviews a number of these papers presented in the Journal in 2006.

A Study on Indoor Air Contaminants Related to Pets in Japanese Dwellings

The behavior of indoor particulate matter as it relates to pets was studied from the viewpoint of architectural hygiene. The viable particles from pets can be classified into two types, pathogenic microorganisms and pet allergens. This study investigated Pasteurella, which is a pathogenic organ of Pasteurellosis, dog allergen Can f1 and cat allergen Fel d1 in eight dwellings in Tokyo. In six of these dwellings (the case dwellings), the dogs and/or cats were allowed free access to indoor areas. Pasteurella and the pet allergens were quantified by biochemical and immunological methods, respectively. The relationship between suspended particles and airborne Fel d1 was also examined.Three species, P. canis, P. dagmatis and P. multocida, were isolated from the oral cavity of the dogs and cats. In the six case dwellings, dust allergen Can f1 and Fel d1 ranged from 1 to 1000 μg allergen/g dust and 100 to 5000 μg/g, respectively. The indoor air of the case dwellings contained concentrations of airborne Fel d1 ranging from 10 to 100 ng of allergen/m3 air. In addition, there was a significant relationship between the distributed concentration of suspended particles larger than 5 μm and airborne Fel d1 (P< 0.01). These findings suggest that the traditional reduction method for coarse particles, for example the use of a domestic air filtration cleaner, may be effective in removing airborne pet allergens.

Variability of airborne cat allergen, Fel d1, in a public place.

Allergen exposure is a risk to develop an IgE-mediated sensitization. The amount of allergen inhaled per unit time should be related to the amount present in the air, i.e. airborne allergen. Thus, measuring allergen levels in the air would be more relevant than measuring allergen levels in dust. Allergens are present in the air in very minute quantities and usually become airborne after disturbance. Large variation of allergen levels have been found in dust. In this study, we measured variability of airborne cat allergen, Fel d1, in a public place using a high-volume air-sampler. We also studied the distribution and relationship between dust and airborne cat allergens in homes and schools. Air samples were collected at three different airflow rates, i.e. 55, 40, and 30 m3 of air per hour. The concentration of airborne Fel d1 in the community gymnastic hall varied from 1 to 10 pg/m3 within a period of 3 weeks, at airflow rates 55-30 m3/h. The coefficient of variation for repeated samplings was 14-43% (day-to-day variation) and 27-38% (within-day variation). As expected, higher levels of airborne cat allergens were found in homes with cats than in cat-free environments. There was a significant relationship between cat allergen levels in dust and air (r=0.7, P<0.01). Our study demonstrates that when measuring airborne cat allergen a large variation is observed within a day and between days. The large variability of measurement may be explained by the disturbance in the environments. We suggest, that when exposure assessment is made the environment in question should be analyzed, if possible in several occasions.

Quantitative measurement of airborne allergens from dust mites, dogs, and cats using an ion-charging device.

Increasing evidence suggests that children raised with an animal(s) in the house have a decreased risk of becoming sensitized. However, it is not clear whether this phenomenon is related to airborne exposure. To estimate airborne exposure to animal dander and dust mite allergens using a device that can sample large volumes of air silently. The device, which uses an ion-charging technique to move air and to collect particles, was run at 1.7 m3/min for 24 h in 44 homes with and without animals. The allergen collected was measured by ELISA for Fel d 1, Can f 1, Der p 1, and Der f 1. Airborne Fel d 1 was present in all homes with a cat (n=27). The quantities measured, i.e. 0.5-20 microg in 24 h, represent 0.01-0.3 microg Fel d 1 inhaled/day at normal breathing rates (20 L/h). Values for houses without a cat were 0.01-0.05 microg inhaled/day. Airborne Fel d 1 correlated significantly with floor Fel d 1 (r=0.58, P<0.001). Results for Can f 1 were similar in houses with a dog, but this allergen was only detected airborne in two houses without a dog. Neither Der p 1 nor Der f 1 (i.e. <0.01 microg) was detected, which represents < or =1 ng inhaled/day during normal domestic activity. During disturbance airborne mite was detected with both the ion-charging device and a filter run in parallel. For cat and mite allergens there was a close correlation between the two techniques (r=0.84, P<0.001). Exposure to cat or dog allergen airborne in homes with an animal can be up to 100 times higher than exposure to mite allergen. The results are in keeping with a model where immunological tolerance to animal dander allergens results from high exposure.

A “Cat Free” Zone in Schools?

Source: Almqvist C, Larsson PH, Egmar AC, et al. School as a risk environment for children allergic to cats and a site for transfer of cat allergen to homes. J Allergy Clin Immunol. 1999;103(6):1012–1017.In areas where there is little dust mite antigen, cat and dog allergens are the most common indoor sensitizers.1 Sensitization to these pets is significantly related to the presence of asthma.2 Consequently, parents of sensitized asthmatics are encouraged to remove these animals from their homes if present and to avoid any contact with these animals in other settings. These other settings include schools, which are a major site for exposure.3 In this article Almqvist et al in Stockholm looked at the possible mechanisms by which cat allergen is disseminated. They demonstrated that in those classes with few (<10%) cat owners the level of airborne Fel d 1 (cat allergen) was significantly lower than in those classes with many (>25%) cat owners, 0.59 ng/m3 vs 2.94 ng/m3 (p<.01). These levels were intermediate between Fel d 1 levels in homes with or without a cat, 19.8 ng/m3 (p<.001) and 0.15 ng/m3 (p<.001). In classes with many cat owners the airborne Fel d 1 levels did not significantly vary with the site of the sampling (ie, in the breathing zone of, nearby, or across the room from the cat owner). The levels dropped off significantly away from the breathing zone of the cat owner in classes with few cat owners. The level of Fel d 1 on new T-shirts worn by cat owners one evening and to school the next day was 3030 (900–15620) ng. The level of Fel d 1 on a new unworn T-shirt was 0.3 (0.2–2.2) ng (p<.001); this increased to 146 (86–234) ng on a non-cat owner after one day in school with cat owners. Although the airborne levels of Fel d 1 in homes of non-cat owners did not differ whether the student was in a class with few or many cat owners, the mattress levels showed a significant difference, 0.38 μg/g dust vs 0.85 μg/g dust (p<.01).Whether the airborne levels of Fel d 1 reported in the above article are sufficient to sensitize or to elicit asthma symptoms is unknown,4 but low doses of allergen can make the lungs more hyper-reactive.5,6 If this is the case, then in the future might we want to place cat allergic asthmatics in school rooms with fewer cat owners? This would be a difficult suggestion in our society. We now have tobacco smoke free environments for our children. But how far are we willing to change the environment of the group to benefit the few? I doubt that we would, or could, segregate cat owners even if we found that their breath and clothes were a danger to others. For the time being, studies must now be conducted that answer the question of whether the airborne levels of Fel d 1 reported in this article sensitize and/or provoke allergic symptoms.We won’t pussy-foot around: not only is the idea of separating children in school by their allergen exposures potentially discriminatory, it is purr-ticularly impractical.

A Placebo-Controlled Trial of a HEPA Air Cleaner in the Treatmentof Cat Allergy

Wood RA, Johnson EF, Van Natta MLHua Chen P, Eggleston PAAm J Respir Crit Care Med.1581998115120Air cleaners and air filtration devices have enjoyed considerable popularity as a form of environmental control to remedy allergic problems. There are, however, many unanswered questions in regard to their efficacy. This study attempts to address the question of efficacy of the high-efficiency particulate arrestor (HEPA) cleaners in reducing allergen levels and disease activity in the homes of cat-allergic patients who continue to live with the triggering allergen (cat).This study involved adults who had asthma and/or allergic rhinitis. They all had a history of allergic symptoms with cat exposure to the extent they required daily medications. They also had at least one cat in the home.A 1-month baseline period helped to determine the minimum amount of medication needed to control asthma and/or allergic rhinitis symptoms. Daily diaries were kept regarding medication use, peak flow, nasal and chest symptom scores, and sleep difficulty. At a home visit, the number of cats and the presence of carpeting was noted. Baseline air and dust samples were collected in the patient's bedroom. Pillows and mattresses were then covered and bedding was washed weekly. Patients were instructed to keep the cat(s) out of the bedroom. A second home visit was conducted to ensure compliance with the environmental control measures. For the next 3 months, a Honeywell Environcare HEPA filter was placed in the bedroom. This unit provided 15 air changes/hour in a 12- × 15-foot room. In the control group the filter was removed. Home visits occurred every month to sample the air and dust. A timer on the air filter units monitored compliance. Cat antigen, Fel d 1, was measured by enzyme-linked immunosorbent assay (ELISA). Other variables that were evaluated included spirometry, methacholine sensitivity, and radioallergosorbent test (RAST).There were 35 patients in the study; 17 served as the control group. All study patients had cat-induced rhinitis and 28 had cat-induced asthma. Thirteen study patients had one cat and 18 had two. All but 1 patient had carpeting in the bedroom. There were no significant differences between the treatment and control groups in medication use or demographics. There was no change in the level of airborne Fel d 1 in either group during the baseline period when the cat was kept out of the bedroom and covers were in place. When the HEPA filter was added, there was a modest decrease over 3 months in the level of airborne Fel d 1 in the group with the active air filter. The geometric mean level decreased from 3.0 ng/m3 at baseline to 1.7 ng/m3 at 3 months. There was no difference in cat allergen levels in settled dust samples at any point during the study. There was a trend toward decreased nighttime nasal symptoms in the treatment group; however, this did not reach statistical significance. No significant differences were observed in chest symptoms, peak flow measures, sleep, medication use, spirometry, methacholine challenges, or RAST results.The HEPA filter did provide for a significant decrease in Fel d 1 levels in the air. However, those using a HEPA filter did not experience any significant difference in any measure of disease activity for both rhinitis and asthma.It must be noted that this paper does not deal with children at all; however, it does deal with a common problem that affects children. Parents see these forms of allergy treatment advertised and may ask their pediatricians about their efficacy. There are numerous options available for environmental control, many of which have not been studied in any rigorous way. This article points out a number of key concepts using this form of environmental control measure. Airborne levels do decrease, but the new level achieved was not associated with significant differences in disease control. The study emphasizes the importance of avoidance and the lack of efficacy of the HEPA units in this model of allergy.

Relationship between mite, cat, and dog allergens in reservoir dust and ambient air.

Standardized methods to measure allergen exposure are essential to assess the relationship between exposure, sensitization, and asthma. Most studies have measured allergen levels in reservoir dust, although air samples may be more representative as a measure of inhaled allergen. The aim of this study was to define the relationship between mite, cat, and dog allergen content in the reservoir dust and the levels in the ambient air. Dust samples from the living-room floor (LF) and sofa (S) were collected in 127 homes: 62 without and 65 with pets (31 dogs, 34 cats). Air samples were taken in the same room, with a high-volume pump for 1 h (flow 60 l/min). Der p 1, Fel d 1, and Can f 1 were determined by mAb-based ELISA. Airborne Der p 1 was below the detection limit (0.8 ng/m3) in all homes, with reservoir levels (GM and range) being 1.14 microg/g (0.2-66) and 1.15 microg/g (0.2-127) in LF and S, respectively. Airborne Can f 1 was detected in 40/62 homes without pets (range 0.6-12.4 ng/m3) and in all homes with dogs (range 0.5-99 ng/m3). In the multiple linear regression analysis, Can f 1 level in the LF was an independent correlate of the airborne Can f 1 (P=0.01, homes with dogs; P=0.04, homes without dogs). Fel d 1 was detected in the air in 16/62 homes without pets (range 0.16-1.8 ng/m3) and in all homes with cats (range 0.4-22.3 ng/m3). Fel d 1 level in the LF was an independent correlate of the airborne Fel d 1 in homes without cats (P=0.008), but airborne levels in homes with cats did not correlate with reservoir levels. The aerodynamics of each allergen must be taken into account when assessing exposure: while levels in reservoir dust are the best available index for mite allergens, airborne levels might be more suitable for defining exposure to pets. If air samples are difficult to obtain, levels of Can f 1 and Fel d 1 in the LF samples should be used as a surrogate measure of personal exposure.

Fel d 1 and Can f 1 in settled dust and airborne Fel d 1 in allergen avoidance day-care centres for atopic children in relation to number of pet-owners, ventilation and general cleaning.

Special day-care centres for atopic children have been established in Sweden. To study concentrations of cat (Fel d 1) and dog (Can f 1) allergens in settled dust and airborne cat allergen in day-care centres in relation to pet ownership among children and staff, ventilation and general cleaning. Twelve allergen avoidance day-care centres and 22 conventional day-care centres were included in the study. Settled dust was collected and analysed with ELISA. Airborne cat allergen levels were measured in eight allergen avoidance and seven conventional centres with a personal air sampler and analysed with an amplified ELISA. Air change rate per hour (ACH) was measured. A questionnaire which focused on keeping of cat and dog among staff and children and frequency of general cleaning was used. In the allergen avoidance day-care centres neither children nor staff reported ownership of cats or dogs, compared with 21/22 of the conventional centres in which children and staff kept furred animals. Fel d 1 and Can f 1 were found in settled dust in all day-care centres. In the allergen avoidance compared with the conventional centres the concentrations of Fel d 1 and Can f 1 were lower, Fel d 1: median 0. 64 microg/g vs 5.45 microg/g and Can f 1: 0.39 microg/g vs 2.51, both P < 0.001, and airborne Fel d 1 was also lower in the allergen avoidance centres compared with the control centres, 1.51 ng/m3 vs 15.8 ng/m3, P = 0.002. A correlation was found between airborne and settled Fel d 1, rs = 0.75, P < 0.001. Furthermore, a correlation was found between increased ACH and decreased levels of Fel d 1 in the air in the day-care centres with no cat-owners, rs = - 0.86, P = 0.007. No relation was found between levels of cat or dog allergen and amount of general cleaning. Not keeping pets seems to reduce children's exposure to pet-allergen in their 'working environment'. Additionally, appropriate ventilation seems to reduce Fel d 1 in the air in day-care centres.

Effect of two different types of vacuum cleaners on airborne Fel d 1 levels.

Vacuum cleaners may increase the level of airborne allergens by leakage through the cleaners or by disturbance of floor dust by the exhaust air produced. The aim of this study was to evaluate the short-term effect of vacuum cleaning with two different types of cleaners on airborne cat allergen analyzed by a biologic and by an immunochemical test. Ten homes with cats were cleaned in random order with a 1-week interval by a traditional canister type vacuum cleaner (T) and a semi-stationary vacuum cleaner (S) that conducts the air to the exterior through a valve in the wall. Airborne particles were collected by air sampling for 2 hours and cat allergen, Fel d 1, was quantified biologically by basophil histamine release test (HR test) and immunochemically by enzyme linked immunosorbent assay (ELISA). Using the S resulted in smaller amounts of airborne cat allergen than the T (mean 2.1 ng/m3 air (range .8 to 12.5) versus 5.2 ng/m3 (1.3 to 13.3), P < .002 measured by ELISA). Results from ELISA and HR test correlated well (r = .91, P < .001). The use of S with exhaust to the outside of the dwelling gave rise to less airborne low particle size allergen during the cleaning procedure than a T method. The basophil histamine release test could be a valid alternative method to establish allergen content in environmental samples especially in allergen systems with no available monoclonal antibodies.

Effects of various vacuum cleaners on the airborne content of major cat allergen (Fel d 1).

It has been shown that a vacuum cleaner (VC) can increase airborne cat allergen levels. This study aimed to compare the degree of leakage of airborne Fel d 1 levels among five different VCs, both under laboratory conditions and in an apartment with cats. Three of the VCs were marketed as antiallergic: a HEPA filter VC (VC A), a water impingement and HEPA filter VC (VC B), and a foam fabric filter VC (VC C). The other two were standard VCs: VC D and VC E. VCs were tested in a 20 m3, airtight, experimental room and in a 53 m3 living room in an apartment with three cats. Air was sampled with a glass-fiber filter and an impinger at 20 l/min for 30 min before, during, and after vacuuming. Airborne Fel d 1 was measured with a two-site monoclonal ELISA assay. In the experimental room, no airborne Fel d 1 level was measured before using the VCs. After introducing a dust sample containing Fel d 1 in the VCs, we found that VCs A, B, and E did not provoke any increase in airborne Fel d 1. In contrast, VCs C and D significantly increased airborne Fel d 1 levels (GM: 4.9 and 5.3 ng/m3, respectively). In the apartment, all VCs induced an increase in airborne Fel d 1, which was carried by particles greater than 5 microm. However, VCs C and D provoked significantly greater increases in airborne Fel d 1 than VCs A, B, and E (P=0.0001). Our results suggest that: 1) The two VCs with leakage in the experimental room had greater leakages in the apartment. 2) In the apartment with cats, all VCs provoked increases in airborne Fel d 1, primarily carried by large particles. 3) Given the increased marketing of "antiallergic" VCs, further studies are needed to standardize methods for testing airborne allergen leakage by VCs.

Distribution, aerodynamic characteristics, and removal of the major cat allergen Fel d 1 in British homes.

BACKGROUND: Sensitisation to cat allergen (Fel d 1) is an important risk factor for asthma in the UK. A study was undertaken to investigate the distribution of cat allergen in...

Domestic allergens in public places III: house dust mite, cat, dog and cockroach allergens in British hospitals.

Exposure and sensitization to indoor allergens is a major cause of asthma. This study investigated the levels of house dust mite, cat, dog and cockroach allergens in the dust and air in hospitals and the effects of regular vacuum cleaning on allergen levels in hospital chairs. Der p 1, Fel d 1, Can f 1 and Bla g 2 were measured in the dust collected by vacuuming upholstered chairs and a 1 m2 area of carpet and mattress in 14 hospitals. Air samples were collected using an air sampler (flow rate 60 L/min) on 10 separate days for 4 h in the outpatient department in one of the hospitals during busy clinics when patients were waiting for their appointments. In addition, dust samples were collected on four occasions, at 4-weekly intervals, from 36 fabric covered chairs in the outpatient area of a busy chest clinic by vacuuming each chair for 2 min. During the intervening weeks, 18 of the chairs (active group) were each cleaned by vacuuming for 1 min, three times per week. Der p 1, Fel d 1, Can f 1 and Bla g 2 were assayed using monoclonal antibody-based ELISA. In total, 83 carpets, 69 mattresses and 42 upholstered chairs were sampled. The levels of dust mite allergen Der p 1 and cockroach allergen Bla g 2 found in the hospital setting were low. High levels of Fel d 1 (GM 22.9 microg/g, range 4.5-58) and Can f 1 (GM 21.6 microg/g, range 4-63) were found in upholstered chairs. Airborne Can f 1 was detected on every occasion (range 0.12-0.56 ng/m3), whilst detectable airborne Fel d 1 was found on 7 out of the 10 sampling days (range 0.09-0.22 ng/m3). Der p 1 and Bla g 2 were below the detection limit in all airborne samples. Following repeated vacuuming the mean cat and dog allergen levels decreased significantly (P<0.001) and were almost fivefold lower in the vacuumed chairs compared with the control group. Low levels of mite allergen are unlikely to be of any clinical significance to mite-sensitive asthmatic patients. However, upholstered chairs in hospitals constitute a significant reservoir of cat and dog allergen. Inhalation of airborne allergen in patients attending their hospital appointment may exacerbate asthma in those highly allergic to cats or dogs. These results question the wisdom of introducing soft furnishings and carpets into hospitals. Three-times weekly vacuuming significantly reduces allergen levels in upholstered chairs.

Evaluation of different techniques for washing cats: Quantitation of allergen removed from the cat and the effect on airborne Fel d 1

Background and Objective: The purpose of this study was to examine the quantity and distribution of the major cat allergen, Fel d 1, on cats and to evaluate the efficacy of washing, both in removing allergen from the cat and reducing airborne allergen levels. Methods: Airborne samples were collected on four glass fiber filters in a 30 m 3 room, before and 3 hours after serial washing of eight cats (45-minute sampling at 18 L/min for each filter). Aliquots of hair and bath water were also collected and assayed for Fel d 1 content. Results: Extracting cat hair with tap water or pet shampoo for 3 minutes removed mean levels of 191 and 245 μg of Fel d 1 per gram of hair, respectively; the quantity of allergen on samples of cat hair ranged from 1 μg/gm to more than 1770 μg/gm. The highest concentration of allergen was found on hair from the neck. Estimates of the total Fel d 1 on the cat, based on shaving the whole cat, ranged from 3 to 142 mg (mean = 67 mg). Washing cats reduced airborne allergen 3 hours later. Washing three cats at weekly intervals for 5 weeks in a veterinarian's office produced a mean decrease of 44% in airborne Fel d 1 ( n = 15, p < 0.02). Washing three cats by immersion for 3 minutes at weekly intervals for a 1-month period produced a mean decrease in airborne allergen of 79% ( n = 12, p < 0.001). However, after repeated washing, the airborne levels before the next wash were not consistently decreased. The quantity of Fel d 1 removed by immersion varied from 1 to 35 mg. Conclusion: Cats carry large quantities of Fel d 1, only a small proportion of which (~0.002%/hr) becomes airborne. Washing cats by immersion will remove significant allergen from the cat and can reduce the quantity of Fel d 1 becoming airborne. However, the decrease is not maintained at 1 week. (J Allergy Clin Immunol 1997;100:307-12.)

Domestic allergens in public places II: dog (Can f 1) and cockroach (Bla g 2) allergens in dust and mite, cat, dog and cockroach allergens in the air in public buildings

Sensitization and exposure to indoor allergens are the major risk factors for asthma. It is possible that significant exposure to domestic allergens occurs outside the home. To investigate the levels of Can f 1 and Bla g 2 in the dust from carpeted floors and upholstered seats in public buildings and public transport and the airborne concentrations of Der p 1, Fel d 1, Can f 1 and Bla g 2 in schools and offices. Can f 1 and Bla g 2 were measured in the dust collected by vacuuming a 1 m2 area of carpet, as well as upholstered seats in five schools, six hotels, four cinemas, six pubs, three buses and two trains. Dust was also collected from the bedroom carpet, living room carpet, mattress and sofa in 20 homes with and 20 homes without a dog in the same area. Personal airborne sampling (2 L/min) was conducted for 8 h in offices (n = 16) and classrooms (n = 9). In addition, airborne samples in schools were collected using a high volume pump (60 L/min) for 1 h in three classrooms immediately after the children vacated the school. Can f 1, Bla g 2, Der p 1 and Fel d 1 were assayed using a two-site monoclonal antibody-based ELISA. Can f 1 was detected in all dust samples from public places, ranging from 0.2 to 52.5 micrograms/g. Significantly higher levels were found in upholstered seats (geometric mean--GM 9.4 micrograms/g) than in carpets (GM 1.5 micrograms/g; P < 0.001), and levels of Can f 1 > 10 micrograms/g were found in 40% of upholstered seats in public places. Can f 1 was significantly higher in upholstered seats in public places than in sofas in homes without a dog (GM 1.8 micrograms/g; P < 0.001). Detectable levels of Bla g 2 were found in all of the schools (GM 2.4 U/g, range 0.8-4.4 U/g). Bla g 2 concentration greater than 2U/g (provisional threshold level representing risk of sensitization) was measured in 65% of the classrooms sampled. Der p 1 and Bla g 2 were below the detection limit in all airborne samples. However, airborne Fel d 1 and Can f 1 were detected in schools and offices, albeit in low concentrations. Upholstered seats from public places constitute a reservoir for the accumulation of dog allergen, and a source of exposure to Can f 1 inside public buildings or on public transport. Exposure to cockroach allergens in schools may be important for cockroach sensitized asthmatic children.