The kidneys in aging]

In this study, we investigated indoor air quality and symptoms of respiratory illness in 264 nursing workers at 28 day-care centers in Taipei. Geometric mean concentrations of indoor and outdoor bacteria were 735 colony-forming units in air (CFU/m3) and 384 CFU/m3, respectively. In addition, geometric mean concentrations of indoor and outdoor fungi were 1,212 CFU/m3 and 1,032 CFU/m3, respectively. Aspergillus, Cladosporium, and Penicillium-microfungi that occurred most commonly-were found indoors and outdoors. Geometric mean concentrations of house dust mite allergens, Der p I and Der p V, were 58 ng/g dust and 14 ng/g dust, respectively. In addition, the observed high prevalence of dampness or mold problems in the day-care centers indicated that dampness was very common in this subtropical region. We found a significant relationship between dampness and work-related sick building syndrome in the day-care-center workers. Furthermore, concentrations of fungi were lower in the day-care centers equipped with air conditioners/air cleaners than in centers that lacked such equipment. Also, Aspergillus was associated strongly with work-related sick building syndrome in the day-care-center workers.     

Damage occurs early in systemic vasculitis and is an index of outcome

The use of products containing PCB in buildings resulted in indoor air contaminations. The search for appropriate measures is hampered by several different uncertainties in the regulatory toxicological process. These refer to problems in exposure assessment including measurement approaches, the toxicological evaluation of health risks including the derivation of a tolerable intake and the use of TCDD toxicity equivalency factors and finally the legal consequences of health risk evaluation. Since no consensus on these aspects has been achieved, the regulatory consequences vary considerably from one German state government to the other. FAO/WHO have not been able to arrive at a satisfactory supranational recommendation of a tolerable intake for PCB.     

Primary aromatic amines from side-stream cigarette smoke are common contaminants of indoor air

A very sensitive mass-spectrometry method has been developed for the analysis of aromatic amines in tobacco smoke and in indoor air. Cigarettes were smoked with a smoking machine; the amines from the smoke were trapped in a 5% HCl water solution containing internal standards and detected by gas chromatography/mass spectrometry in the selected-ion-monitoring (SIM) mode. The amines measured were the following: aniline, 2-toluidine, 3-toluidine, 4-toluidine, 2-ethylaniline, 3-ethylaniline, 4-ethylaniline, 2,3-dimethylaniline, 2,4-dimethylaniline, 2,5-dimethylaniline, 2,6-dimethylaniline, 1-naphthylamine, 2-naphthylamine, 2-methyl-1-naphthylamine, 2-aminobiphenyl, 3-aminobiphenyl and 4-aminobiphenyl. We analyzed nine brands of cigarettes sold commercially in Italy (Gauloise, Nazionali, Marlboro, Camel, MS, MS mild and MS lights), with and without filter. Main-stream smoke contained a lower amount of aromatic amines than side-stream smoke: the total level of these amines in main-stream smoke ranged from 200 to 1300 ng/cigarette, whereas the level of aromatic amines in side-stream smoke varied from 20,000 to 30,000 ng/cigarette. The smoke of black-tobacco cigarettes had higher levels of aromatic amines compared to light-tobacco cigarettes and the filters significantly reduced aromatic amines in main-stream smoke. We also determined the levels of aromatic amines in ambient air, offices and houses. Some aromatic amines (aniline and toluidine) were detected in ambient air, as well as in rooms of non-smokers. Most measurements showed a considerable contamination of aromatic amines derived from side-stream smoke, which was detected also in parts of the buildings in which smoking was not allowed.     

Formal Definition of a User-Adaptive and Length-Optimal Routing Graph for Complex Indoor Environments

Car routing solutions are omnipresent and solutions for pedestrians also exist. Furthermore, public or commercial buildings are getting bigger and the complexity of their internal slructure has increased. Consequently, the need for indoor routing solutions has emerged. Some prototypes are available, but they still lack semantically-enriched modelling (e.g., access constraints, labels, etc.) and are not suitable for providing user-adaptive length-optimal routing in complex buildings. Previous approaches consider simple rooms,concave rooms, and corridors, but important characteristics such as distinct areas in huge rooms and solid obstacles inside rooms are not considered at all, although such details can increase navigation accuracy. By formally defining a weighted indoor routing graph, it is possible to create a detailed and user-adaptive model for route computation. The defined graph also contains semantic information such as room labels, door accessibility constraints, etc. Furthermore, one-way paths inside buildings are considered, as well as three-dimensional building pans, e.g., elevators or stairways. A hierarchical structure is also possible with the presented graph model.     

Nature and amount of aerial pollutants from livestock buildings

The air in animal housing contains gases, odours, dust particles and microorganisms which are discharged by way of the ventilation system into the environment. There is increasing concern within parts of the population that these compounds may affect the respiratory health of people living close to livestock enterprises. A brief survey is presented on airborne emissions from livestock buildings. About 136 gaseous compounds are analysed in animal house air of which only 22 are quantified. The most environment-related compounds are ammonia and methane. It is assumed that German animal husbandry emits up to 750,000 Mg ammonia per year. The concentrations of airborne microorganisms in livestock buildings are between some 100 and several 1000 per liter. Staphylococcae, streptococcae, colilike bacteria, fungi, moulds and yeasts are regularly found. The 24 h average concentrations of dust in animal barns vary considerably. In poultry houses the highest inhalable resp. respirable dust concentrations (up to 10 mg/m3 resp. 1.2 mg/m3) were found, followed by pig houses (5.5 mg/m3) and cattle barns (1.22 mg/m3 resp. 0.17 mg/m3). The concentrations of endotoxins in the airborne dust can range from 0.6 ng/m3 (cattle, respirable dust) to 860 ng/m3 (laying hens, inhalable dust). The presently discussed occupational health threshold at the workplace is around 5 ng/m3 (50 EU/m3). The emission rate for respirable dust from piggeries is at about 60 mg/h, from poultry houses nearly 300 mg/h and from cattle barns at 20 mg/h, related to 500 kg liveweight of the animals. Little is known about the distances these particles are transported through the air outside the animal buildings.     

Indoor air quality impacts of ventilation ducts: ozone removal and emissions of volatile organic compounds

The concentrations of contaminants in the supply air of mechanically ventilated buildings may be altered by pollutant emissions from and interactions with duct materials. We measured the emission rate of volatile organic compounds (VOCs) and aldehydes from materials typically found in ventilation ducts. The emission rate of VOCs per exposed surface area of materials was found to be low for some duct liners, but high for duct sealing caulk and a neoprene gasket. For a typical duct, the contribution to VOC concentrations is predicted to be only a few percent of common indoor levels. We exposed selected materials to approximately 100-ppb ozone and measured VOC emissions. Exposure to ozone increased the emission rates of aldehydes from a duct liner, duct sealing caulk, and neoprene gasket. The emission of aldehydes from these materials could increase indoor air concentrations by amounts that are as much as 20% of odor thresholds. We also measured the rate of ozone uptake on duct liners and galvanized sheet metal to predict how much ozone might be removed by a typical duct in ventilation systems. For exposure to a constant ozone mol fraction of 37 ppb, a lined duct would initially remove approximately 9% of the ozone, but over a period of 10 days of ozone removal efficiency would diminish to less than 4%. In an unlined duct, in which only galvanized sheet metal is exposed to the air-stream, the removal efficiency would be much lower, approximately 0.02%. Therefore, ducts in ventilation systems are unlikely to be a major sink for ozone.     

Airborne Particles in New Museum Facilities

Over the period July 1996–April 1998, airborne particle concentrations and chemical composition were measured both inside and outside the new J. Paul Getty Museum outside Los Angeles. The purpose of these experiments was to determine the relationship between the stages of construction and operation of the building and the soiling hazard to the collections. Particular attention was paid to tracking the concentrations of fine black soot particles and mineral dust particles. The time needed to “air out” the building following construction can be seen from the data collected, as well as the inherent particle removal efficiency of the filters within the building ventilation system, and the effect of entry of the general public into the building. During the period of observation when the building was under construction, weekday coarse dust particle concentrations on occasion reached very high levels (600–1,100?μg?m?3; 24 h average), falling to relatively low values averaging 26?μg?m?3 over weekend periods when construction activity subsided. In March, 1997, with construction largely completed and with the heating, ventilation, and air conditioning (HVAC) system in full operation, indoor coarse dust concentrations fell to 1.7% of those outdoors. Beginning at this time, indoor fine particle concentrations relative to those outdoors declined steadily over a period of about one to two months, reaching levels of 3.9% of those outdoors during the period June 3–December 6, 1997 when construction was completed but before entry of the general public into the building. Thus, the coarse and fine particle removal efficiencies of the building HVAC system absent major indoor sources are at least 98 and 96%, respectively. Following the opening of the museum to the public, indoor particle concentrations increased by approximately 1?μg?m?3 in each of the coarse dust and fine smoke-size particle size ranges indicating that there is a small but measurable effect due to increased air infiltration as doors are opened and closed more frequently and due to particles shed by the visitors. Indoor particle concentrations inside the new Getty Museum in the presence of the general public are only 3.2?μg?m?3 of coarse dust and 1.8?μg?m?3 of fine particles on average over the period January–April, 1998.     

Airborne hexavalent chromium in southwestern Ontario

This study reports the first field measurements of airborne hexavalent chromium (Cr(vi)) in southwestern Ontario. Hexavalent chromium was identified as an inhalation carcinogen and an air toxic of concern during the 1991-93 Windsor Air Quality Study. The results of that study indicated that approximately 20% of the routinely monitored ambient airborne chromium (Cr) was in the hexavalent form. In addition, the range of carcinogenic health risks attributable to airborne Cr(vi) was determined to be between 1.4 x 10(-5) and 3.0 x 10(-4) for people living in the Windsor area. During the summer of 1993, analyses of concurrent indoor and outdoor 24-hour air quality samples taken at 33 residences in Hamilton resulted in geometric mean Cr(vi) concentrations of 0.20 ng/m3 and 0.55 ng/m3, respectively, and little or no relationship between the indoor and outdoor sample sets. During the summer of 1994, an airborne Cr(vi) size-fraction study was conducted in Hamilton, the results of which suggested that the majority of the Cr(vi) was in the inhalable fraction.     

Housing and health

Most of our lifetime we stay indoors. Both the home environment and housing behaviour may promote health complaints and disease. The term "sick building syndrome (SBS)" is used to describe a complex of unspecific symptoms attributed to staying in an indoor environment. In contrast, "building-related illness" (BRI) designates specific diseases attributed to special factors of indoor environment. A number of factors is known to influence health in the indoor environment, such as indoor emissions, ambient air, indoor climate (temperature, air flow, humidity) optical influences, water supply and sewage disposal, sound waves (noise, vibrations), non-ionising radiation, construction and characteristic design features of a home (e.g. floor area, functionality) and also psychological factors. Epidemiological studies have revealed that dark and noisy homes, rooms with insufficiently insulated external walls, single glazing, heating by gas heaters fitted to external walls and too low humidity of indoor air will increase morbidity. A checklist based on medical considerations is presented permitting assessment of the health relevance of important areas/factors of the home environment by means of a scoring system.     

Nasal patency and biomarkers in nasal lavage--the significance of air exchange rate and type of ventilation in schools

OBJECTIVES: The aim of the present study was to examine the relationships between the ventilation rate and the type of ventilation system, on the one hand, and objective nasal measures, on the other. METHODS: A standardized investigation, including acoustic rhinometry and nasal lavage, was performed in the school environment. All 279 school personnel working in the main buildings of 12 randomly selected primary schools in the municipality of Uppsala were invited, and 234 (84%) participated. The dimensions of the nasal cavity were measured with acoustic rhinometry. Eosinophil cationic protein (ECP), myeloperoxidase (MPO), lysozyme, and albumin were analyzed in the lavage fluid. The air exchange rate and the room temperature were measured in the classrooms. Relationships between nasal symptoms, nasal patency, and the concentration of biomarkers, on the one hand, and the type of ventilation system, the air exchange rate, and the temperature, on the other, were analyzed by both crude bivariate analysis and multiple regression models, controlling for the type of ventilation, the air exchange rate, room temperature, age, gender, smoking, atopy, and the urban vicinity of the school. RESULTS: A lower degree of nasal patency as measured by acoustic rhinometry and increased levels of ECP and lysozyme in nasal lavage were associated with a lower air exchange rate in the schools. Although mechanically ventilated schools had higher air exchange rates, they were associated with more nasal symptoms, and nasal mucosal swelling and with increased lavage levels of ECP and lysozyme as compared with schools with natural ventilation only. In contrast, 12 subjects working in a school with mechanical displacement ventilation had more patent noses and lower levels of inflammatory markers as compared with the personnel in schools with natural ventilation only. CONCLUSION: Our results indicate that both a low air exchange rate and mechanical ventilation systems based on dilution can be associated with reduced nasal patency and an inflammatory biomarker response of the nasal mucosa among school personnel. The only school with sufficient ventilation according to the current Swedish recommendations had a displacement system and the fewest signs of nasal reactions among the personnel.     

Low frequency of Ras gene mutation in spontaneous and gamma-ray-induced thymic lymphomas of scid mice

BACKGROUND: Workers in the poultry industry have increased frequencies of respiratory health problems. The aim of the present study was to investigate acute health effects from exposure in poultry houses and to compare the health effects observed in a cage rearing system and the alternative "cage-less" rearing system for laying hens. METHODS: Thirty-four subjects were exposed for 3 hr in confined poultry houses. The subjects were randomized into three groups: one was exposed in a building with a cage rearing system and the two other groups were exposed in buildings with a cage-less system, with either young hens and fresh bedding material or with older hens and old bedding material. RESULTS: Inhalable dust levels were approximately 4 mg/m3 in the buildings with the cage-less system and 2 mg/m3 in the building with cage rearing system; the endotoxin concentration was approximately 100 ng/m3 in both systems. Bronchial responsiveness to methacholine increased approximately fivefold in all groups following exposure. The concentration of the proinflammatory cytokine interleukin-6 (IL-6) increased in nasal lavage fluid and in peripheral blood as a result of the exposure. The number of leukocytes in peripheral blood increased only in the groups exposed among loose laying hens. CONCLUSION: In the present study, we have demonstrated among previously non-exposed subjects, that 3-hr exposure in confined buildings for egg production induces an acute inflammatory reaction in the upper airways and increased bronchial responsiveness. There is a tendency towards stronger reactions in the groups exposed in the buildings with loose housing for laying hens.     

Pilot Study for the Performance of a New Demand Control Ventilation System in Hong Kong

There are different ventilation control methods for outdoor air quantity in air-conditioned spaces to reduce the energy consumed in cooling the outdoor air. Demand controlled ventilation (DCV) is an important strategy to control the outdoor air quantity. However, the current practice in DCV systems creates several problems for air-conditioned office buildings. Although metabolic carbon dioxide (CO2) concentration is mainly used as a surrogate indicator for ventilation adequacy, the conventional DCV system does not seriously consider the placement location of the CO2 sensor, and it does not take into account the adverse effects of the consequential increase in pollutant concentrations in the indoor space when the fresh airflow rate is reduced. In this study, a long period of subjective and objective measurements were conducted in an occupied office to examine its suitability for conversion to a new demand controlled ventilation system (nDCV). After the feasibility investigation, an nDCV system was developed to optimize the energy consumed for outdoor air ventilation while providing the desirable thermal comfort and indoor air quality. The true optimization of this nDCV is achieved by a new concept of the optimized indoor air quality window which determines the most representative locations for the indicator sensors. A minimum ventilation rate is determined by a calibration procedure for the pollutant inventory of a building, taking into account the infiltration characteristics. Radon gas, which is a notorious carcinogenic indoor pollutant, is used as a reference to determine the minimum fresh airflow rate. The findings show that this nDCV system reduced 16% of fresh air cooling energy consumption without jeopardizing the thermal comfort and indoor air quality.     

Emission of particulates from a pig farm with central air exhaust in the pig stall

There is increasing concern that airborne dust and particulates from animal enterprises which are emitted into the environment may impair the health of people living in nearby residential areas. Investigations were carried out to trace the distribution of particulate emissions from a piggery in the vicinity by means of an aerosol lidar. Additionally, dust was sampled with a high volume impactor (HVS) at two places downwind (50 m, 115 m) and at a reference point 50 m upwind the piggery. The total dust concentraction in the animal house air varied between 0.2 and 1.0 mg/m3 within 24 hours. 50 m downwind the building 0.08 mg/m3 dust was measured by means of the HVS. At a distance of 115 m downwind the same concentrations (0.037 mg/m3) as the reference point (0.037 mg/m3 upwind the animal house were found. The endotoxin concentrations were 60 ng/m3 (50 m downwind), 15 ng/m3 (115 m downwind) and 9 ng/m3 (50 m upwind). The lidar signals discriminated clearly between the density of the air directly above the exhaust chimney and the 115 m downwind position. It seems that the lidar technique in combination with high volume impaction form an useful tool to describe the distribution distance of particulate pollutants farm animal housing.     

Medical Records for Building Health Management

Medical records provide essential information for evaluating a patient’s health. Without them, it would be difficult for doctors to make accurate diagnoses. Similar to diagnoses in medical science, building health management also requires building medical records for making accurate diagnoses. At later stages of a building’s life cycle, when the budget is limited, organizations responsible for building repairs and maintenance are unable to digitalize building health diagnoses and keep complete medical records of buildings; as a result, maintenance crews usually cannot fully understand buildings’ overall health conditions and their medical histories, which may result in erroneous diagnoses directly or public safety dangers indirectly. Using the problem-oriented medical record adopted for the medical diagnosis of human diseases, this paper designs a building medical record (BMR), which allows simple electronic archiving, and evaluates its practicability with a case study of school buildings. The purpose of a BMR is to enable maintenance engineers (building doctors), building managers, and contractors of school buildings to have low-cost access to required information for making complete evaluations and maintenance suggestions for buildings.     

Large-Eddy Simulations on Indoor/Outdoor Air Quality Relationship in an Isolated Urban Building

The airflow, pollutant dispersion and penetration of outdoor pollutants indoor in an isolated urban building are investigated computationally. The computation involves solving the two-dimensional Navier–Stokes equations using large eddy simulations based on the Smagorinsky subgrid scale model. The simulations involve investigations of the phenomena of airflow and pollutant dispersion in both indoor and outdoor environments under different Reynolds numbers with distinct combinations of building height, floor height, and building width. Pollutants originate from outdoor, located at the datum level of the windward side of the building. The objective is to study how outdoor pollutants penetrate indoor and relate this pattern to different building geometric configurations. The gradual increase in Reynolds number significantly favors pollutant transportation into the indoor environment and thus eventually changes the indoor/outdoor (IO) air ratio. Moreover, the value of the IO air ratio is particularly found to be highly affected by building height due to the capability of climbing over and escaping from the roof of the building. Results also show that the IO air ratio is dependent on the position of the sampling, which has been ignored in many previous experimental works. The research work poses important questions of indoor air quality as well as field measurements of the IO parameter.     

Asthma among secondary schoolchildren in relation to the school environment

BACKGROUND: Poor indoor air quality has been suggested to be related to the increase in the prevalence of asthma that has occurred in the western world, especially among children and young persons. Apart from the home, school is the most important indoor environment for children. OBJECTIVES: The aims were to study the prevalence of current asthma among secondary pupils and its relationship to the school environment, but also to personal factors and domestic exposures. METHODS: Data on asthmatic symptoms, other health aspects, and domestic exposures were gathered using a questionnaire which was sent to 762 pupils in the seventh form (13-14 years old) in 11 randomly chosen schools in the county of Uppsala in Sweden. Pupils answering 'yes' to having had asthma diagnosed by a physician, and having had recent asthma attacks, or who used asthma medication were defined as having current asthma. Data on exposures at school were gathered by measurements in 28 classrooms. The relationship between asthma and exposures was analysed by multiple logistic regression. RESULTS: The questionnaire was completed by 627 (82%). Current asthma was found among 40 pupils (6.4%). Current asthma was more common in those who had an atopic disposition, or food allergy, or who had attended a day care centre for several years. Controlling for these factors, current asthma was related to several factors in the school environment. There were more pupils with current asthma in schools that were larger, had more open shelves, lower room temperature, higher relative air humidity, higher concentrations of formaldehyde or other volatile organic compounds, viable moulds or bacteria or more cat allergen in the settled dust. CONCLUSIONS: Although the pupils attended school for a minor part of their time, our study indicates that the quality of the school environment is of importance and may affect asthmatic symptoms.     

Down-regulation of human FEN-1 gene expression during differentiation of promyelocytic leukemia cells

The presence of aflatoxin in corn and corn dust during relatively normal years and the increased risk of Aspergillus flavus infestation during drought conditions suggest that airborne agricultural exposures should be of considerable concern. Liquid extraction, thin layer chromatography, and high pressure liquid chromatography were used for the analysis of aflatoxin B1 in grain dust and bulk corn samples. A total of 24 samples of airborne dust were collected from 8 farms during harvest, 22 samples from 9 farms during animal feeding, and 14 sets of Andersen samples from 11 farms during bin cleaning. A total of 14 samples of settled dust and 18 samples of bulk corn were also collected and analyzed. The airborne concentration of aflatoxin B1 found in dust collected during harvest and grain unloading ranged from 0.04 to 92 ng/m3. Higher levels of aflatoxin B1 were found in the airborne dust samples collected from enclosed animal feeding buildings (5-421 ng/m3) and during bin cleaning (124-4849 ng/m3). Aflatoxin B1 up to 5100 ng/g were detected in settled dust collected from an enclosed animal feeding building; however, no apparent correlation was found between the airborne concentration of aflatoxin B1 and its concentration in settled dust or bulk corn. The data demonstrate that farmers and farm workers may be exposed to potentially hazardous concentrations of aflatoxin B1, particularly during bin cleaning and animal feeding in enclosed buildings.     

Public health nurse staffing requirements for health examination of infants and children in municipalities of Japan

PURPOSE: Little is known about the impact of school-based primary care on adolescents' use of hospital and emergency room care. METHODS: Students (grades 6-12) in nine Baltimore schools with school-based health centers and four schools without health centers were surveyed in May 1991 using an anonymous classroom questionnaire. Self-reported use of primary care services and emergency rooms and hospitalization were examined over the academic year. Logistic regression was used to assess factors influencing use of health care including the presence of a school health center. RESULTS: Students (n = 3,258) in health center schools and comparison schools reported similar rates of chronic health conditions. Students from schools with health centers were more likely to report seeing a social worker or counselor and more likely to report the use of certain health services in the past 4 years. Self-reported emergency room use (38%) and hospitalization (19%) were common. Students in schools with health centers were less likely to report hospitalization (OR = 0.80, 95% CI = 0.66-0.98). Emergency room use was also lower but only for students attending the school with a health center for more than 1 year (OR = 0.78, 95% CI = 0.62-0.99). Significant predictors of hospital care included reporting one or more chronic health condition, having health insurance, being of African-American race, or older age, and lower grade. CONCLUSIONS: Access to school-based, primary health care for adolescents was associated with increased use of primary care, reduced use of emergency rooms, and fewer hospitalizations. These findings have implications for both access to primary care and funding of school-based primary care.     

Mechanical ventilation protects one-storey single-dwelling houses against increased air humidity, domestic mite allergens and indoor pollutants in a cold climatic region

BACKGROUND: Poor ventilation in modern, highly insulated housing is an important factor in promoting indoor humidity levels to exceed 7 g/kg in cold climatic regions. OBJECTIVE: To investigate the ventilation rate in houses with different ventilation systems in relation to indoor air humidity, domestic mite allergen levels and volatile organic compounds (VOC). METHODS: Measurements were performed regarding ventilation rate, indoor temperature, air humidity, mattress mite allergen concentrations using enzyme-linked immunosorbent assay and total indoor VOC in 59 similarly constructed one-storey single-dwelling houses. In 22 of the houses, a mechanical supply and exhaust ventilation were installed after construction. RESULTS: In only five of the houses with mechanical supply and exhaust ventilation the air exchange rate per hour (ACH) was below 0. 5 compared with 24 of the 29 houses with natural ventilation (OR = 0. 06, CI 95% 0.01-0.2). None of the 23 houses with an ACH >/= 0.5 had an absolute indoor humidity (AIH) of 7 g/kg air or more, compared with 10 of the 36 houses with an ACH < 0.5 (P = 0.01 ). In none of the 23 houses with an ACH >/= 0.5 were concentrations of mite allergen exceeding 2 microg/g of dust found, compared with six of the 36 houses (17%) with an ACH below 0.5 (P = 0.04). Further, 10 of the 34 houses with a total VOC exceeding 200 microg/m3 had mite allergen in mattress dust exceeding 0.5 microg/g, compared with one of the 22 houses with VOC < 200 microg/m3 (P = 0.04). CONCLUSION: The study shows that in modern, highly insulated, one-storey single-dwelling houses in cold temperate regions, mechanical ventilation increases the possibility of reaching an ACH of >/= 5 which protects against indoor humidity levels contributing to mite survival as well as high levels of indoor air pollutants in winter.     

The mitochondrial toxin produced by Streptomyces griseus strains isolated from an indoor environment is valinomycin

Actinomycete isolates from indoor air and dust in water-damaged schools and children's day care centers were tested for toxicity by using boar spermatozoa as an indicator. Toxicity was detected in extracts of four strains which caused a loss of sperm motility, and the 50% effective concentrations (EC50) were 10 to 63 ng (dry weight) ml of extended boar semen-1. The four strains were identified as Streptomyces griseus strains by 16S ribosomal DNA and chemotaxonomic methods. The four S. griseus strains had similar effects on sperm cells, including loss of motility and swelling of mitochondria, but we observed no loss of plasma membrane integrity or depletion of cellular ATP. None of the effects was observed with sperm cells exposed to extracts of other indoor actinomycete isolates at concentrations of >/=5,000 to 72,000 ng ml-1. The toxin was purified from all four strains and was identified as a dodecadepsipeptide, and the fragmentation pattern obtained by tandem mass spectrometry was identical to that of valinomycin. Commercial valinomycin had effects in sperm cells that were identical to the effects of the four indoor isolates of S. griseus. The EC50 of purified toxin from the S. griseus strains were 1 to 3 ng ml of extended boar semen-1, and the EC50 of commercial valinomycin was 2 ng ml of extended boar semen-1. To our knowledge, this is the first report of the presence of ionophoric toxin producers in an indoor environment and the first report of valinomycin-producing strains identified as S. griseus.