Fungal Signature of Moisture Damage in Buildings: Identification by Targeted and Untargeted Approaches with Mycobiome Data.

Identifying microbial indicators of damp and moldy buildings remains a challenge at the intersection of microbiology, building science, and public health. Sixty homes in New York City were assessed for moisture-related damage, and three types of dust samples were collected for microbiological analysis. We applied four approaches for detecting fungal signatures of moisture damage in these buildings. Two novel targeted approaches selected specific taxa, identified by a priori hypotheses, from the broad mycobiome as detected with amplicon sequencing. We investigated whether (i) hydrophilic fungi (i.e., requiring high moisture) or (ii) fungi previously reported as indicating damp homes would be more abundant in water-damaged rooms/homes than in nondamaged rooms/homes. Two untargeted approaches compared water-damaged to non-water-damaged homes for (i) differences between indoor and outdoor fungal populations or (ii) differences in the presence or relative abundance of particular fungal taxa. Strong relationships with damage indicators were found for some targeted fungal groups in some sampling types, although not always in the hypothesized direction. For example, for vacuum samples, hydrophilic fungi had significantly higher relative abundance in water-damaged homes, but mesophilic fungi, unexpectedly, had significantly lower relative abundance in homes with visible mold. Untargeted approaches identified no microbial community metrics correlated with water damage variables but did identify specific taxa with at least weak positive links to water-damaged homes. These results, although showing a complex relationship between moisture damage and microbial communities, suggest that targeting particular fungi offers a potential route toward identifying a fungal signature of moisture damage in buildings.IMPORTANCE Living or working in damp or moldy buildings increases the risk of many adverse health effects, including asthma and other respiratory diseases. To date, however, the particular environmental exposure(s) from water-damaged buildings that causes the health effects have not been identified. Likewise, a consistent quantitative measurement that would indicate whether a building is water damaged or poses a health risk to occupants has not been found. In this work, we tried to develop analytical tools that would find a microbial signal of moisture damage amid the noisy background of microorganisms in buildings. The most successful approach taken here focused on particular groups of fungi-those considered likely to grow in damp indoor environments-and their associations with observed moisture damage. With further replication and refinement, this hypothesis-based strategy may be effective in finding still-elusive relationships between building damage and microbiomes.

Concentrations of Staphylococcus species in indoor air as associated with other bacteria, season, relative humidity, air change rate, and S. aureus-positive occupants.

The aim of this study was to obtain knowledge about concentrations of Staphylococcus aureus, MRSA (methicillin-resistant S. aureus), and other Staphylococcus species in indoor air in Greater Copenhagen and about factors affecting the concentrations. The effects of season, temperature, relative humidity, air change rate (ACR), other bacterial genera, area per occupant, and presence of S. aureus-positive occupants were studied. In samples from 67 living rooms, S. hominis, S. warneri, S. epidermidis, and S. capitis were found in 13-25%; S. saprophyticus, S. cohnii, and S. pasteuri in 5-10%; and S. lugdunensis, S. haemolyticus, S. caprae, S. equorum, S. kloosii, S. pettenkoferi, S. simulans, and S. xylosus in less than 3%. Staphylococcus aureus were found in two of 67 living rooms: spa type t034 (an MRSA) was recovered from a farmhouse, while spa type t509 was found in an urban home. Two species, S. equorum and S. kloosii, were found only in the farmhouse. Staphylococcus was significantly associated with season with lowest concentration and richness in winter. Genera composition was associated with ACR with smaller fractions of Staphylococcus at higher ACR, while richness was significantly and negatively associated with area per occupant. Concentration of Staphylococcus correlated positively with the total concentration of bacteria, but negatively with the total concentration of other bacteria. The concentration of Staphylococcus was not significantly associated with concentrations of the other abundant genera Bacillus, Kocuria, and Micrococcus. In offices with S. aureus-positive occupants, airborne S. aureus was not found. In conclusion, Staphylococcus species constitute a considerable proportion of the airborne bacteria in the studied homes and offices. However, both S. aureus and MRSA had very low prevalence during all seasons. Thus, transmission of S. aureus and MRSA through the air in living rooms in Copenhagen is expected to be limited. The negative associations between ACR and the fraction Staphylococcus constituted out of total bacteria, and between area per occupant and Staphylococcus richness indicate that it might be possible to affect the presence of airborne Staphylococcus in homes.

A Comparison between Temperature-Controlled Laminar Airflow Device and a Room Air-Cleaner in Reducing Exposure to Particles While Asleep.

People spend approximately one third of their life sleeping. Exposure to pollutants in the sleep environment often leads to a variety of adverse health effects, such as development and exacerbation of asthma. Avoiding exposure to these pollutants by providing a sufficient air quality in the sleep environment might be a feasible method to alleviate these health symptoms. We performed full-scale laboratory measurements using a thermal manikin positioned on an experimental bed. Three ventilation settings were tested: with no filtration system operated, use of portable air cleaner and use of a temperature-controlled laminar airflow (TLA) device. The first part of the experiment investigated the air-flow characteristics in the breathing zone. In the second part, particle removal efficiency was estimated. Measured in the breathing zone, the room air cleaner demonstrated high turbulence intensity, high velocity and turbulence diffusivity level, with a particle reduction rate of 52% compared to baseline after 30 minutes. The TLA device delivered a laminar airflow to the breathing zone with a reduction rate of 99.5%. During a periodical duvet lifting mimicking a subject's movement in bed, the particle concentration was significantly lower with the TLA device compared to the room air cleaner. The TLA device provided a barrier which significantly reduced the introduction of airborne particles into the breathing zone. Further studies should be conducted for the understanding of the transport of resuspended particles between the duvet and the laying body.

Indoor and outdoor exposure to ultrafine, fine and microbiologically derived particulate matter related to cardiovascular and respiratory effects in a panel of elderly urban citizens.

To explore associations of exposure to ambient and indoor air particulate and bio-aerosol pollutants with cardiovascular and respiratory disease markers, we utilized seven repeated measurements from 48 elderly subjects participating in a 4-week home air filtration study. Microvascular function (MVF), lung function, blood leukocyte counts, monocyte adhesion molecule expression, C-reactive protein, Clara cell protein (CC16) and surfactant protein-D (SPD) were examined in relation to exposure preceding each measurement. Exposure assessment included 48-h urban background monitoring of PM10, PM2.5 and particle number concentration (PNC), weekly measurements of PM2.5 in living- and bedroom, 24-h measurements of indoor PNC three times, and bio-aerosol components in settled dust on a 2-week basis. Statistically significant inverse associations included: MVF with outdoor PNC; granulocyte counts with PM2.5; CD31 expression with dust fungi; SPD with dust endotoxin. Significant positive associations included: MVF with dust bacteria; monocyte expression of CD11 with PM2.5 in the bedroom and dust bacteria and endotoxin, CD31 expression with dust serine protease; serum CC16 with dust NAGase. Multiple comparisons demand cautious interpretation of results, which suggest that outdoor PNC have adverse effects on MVF, and outdoor and indoor PM2.5 and bio-aerosols are associated with markers of inflammation and lung cell integrity.

An indoor air filtration study in homes of elderly: cardiovascular and respiratory effects of exposure to particulate matter.

BACKGROUND: Exposure to particulate air pollution increases respiratory and cardiovascular morbidity and mortality, especially in elderly, possibly through inflammation and vascular dysfunction. METHODS: We examined potential beneficial effects of indoor air filtration in the homes of elderly, including people taking vasoactive drugs.Forty-eight nonsmoking subjects (51 to 81 years) in 27 homes were included in this randomized, double-blind, crossover intervention study with consecutive two-week periods with or without the inclusion of a high-efficiency particle air filter in re-circulating custom built units in their living room and bedroom. We measured blood pressure, microvascular and lung function and collected blood samples for hematological, inflammation, monocyte surface and lung cell damage markers before and at day 2, 7 and 14 during each exposure scenario. RESULTS: The particle filters reduced the median concentration of PM2.5 from approximately 8 to 4 µg/m3 and the particle number concentration from 7669 to 5352 particles/cm3. No statistically significant effects of filtration as category were observed on microvascular and lung function or the biomarkers of systemic inflammation among all subjects, or in the subgroups taking (n = 11) or not taking vasoactive drugs (n = 37). However, the filtration efficacy was variable and microvascular function was within 2 days significantly increased with the actual PM2.5 decrease in the bedroom, especially among 25 subjects not taking any drugs. CONCLUSION: Substantial exposure contrasts in the bedroom and no confounding by drugs appear required for improved microvascular function by air filtration, whereas no other beneficial effect was found in this elderly population.

Sampling, extraction and measurement of bacteria, endotoxin, fungi and inflammatory potential of settling indoor dust.

Selection of sampling device, sampling location and period are important first steps in the measurement of exposure to bioaerosols in indoor air. The steps following the sampling include treatment of samples and laboratory analysis. In this study, settling bacteria, endotoxin, fungi and serine protease have been measured in Danish homes using Electrostatic Dust Fall Collectors (EDCs). The effects of the presence of occupants, sampling on open surfaces versus in bookcases and treatment of samples have been studied. Concentrations of bacteria and endotoxin were significantly higher when occupants were at home than when they were absent. Across homes, higher concentrations of fungi were found in spring than in winter, as was the total inflammatory potential, while higher concentrations of protease were found in winter than in spring. The placement of the EDCs in bookcases versus on an open surface significantly affected the measured concentrations of bacteria and endotoxin. Direct extraction of EDC cloths caused a higher measured concentration of bacteria, fungi and serine protease than if EDC cloths were extracted post-storage at -20 °C. Extraction of EDC cloths caused an average of 51% and 58% extraction of bacteria and fungi respectively. In conclusion, EDCs should be placed on open surfaces during the sampling, how much occupants are present in their home during sampling and sampling season should be considered, EDC cloths should not be stored in a freezer before extraction of microorganisms, but extraction suspensions can be stored at -80 °C without affecting the number of microorganisms significantly.