Efficacy of three EPA-registered antimicrobials and steam against two human norovirus surrogates on nylon carpets with two backing types.

Carpet cleaning guidelines currently do not include the use of an antimicrobial, except after a bodily fluid event. To address this gap, we compared the efficacy of three antimicrobials-two hydrogen peroxide-based (H2O2) products (A and B) and one chlorine-based product (C)-and a steam treatment against two norovirus surrogates, specifically feline calicivirus (FCV) and Tulane virus (TuV). These tests were performed on nylon carpets with either water-permeable or waterproof backing types. The effect of repeated antimicrobial use on carpet properties was also evaluated. For a carpet with water-permeable backing, products A, B, and C achieved a 0.8, 3.1, and 0.9 log10 PFU/coupon reduction of FCV and 0.3, 2.5, and 0.4 log10 TCID50/coupon reduction of TuV, respectively, following a 30 min contact time. For carpet with waterproof backing, only product B achieved a 5.0 log10 PFU/coupon reduction of FCV and >3.0 log10 TCID50/coupon reduction of TuV, whereas products A and C achieved a 2.4 and 1.6 log10 PFU/coupon reduction of FCV and a 1.2 and 1.2 log10 TCID50/coupon reduction of TuV, respectively. Steam treatment achieved a ≥ 5.2 log10 PFU/coupon reduction of FCV and a > 3.2 log10 TCID50/coupon reduction of TuV in 15 seconds on the carpet with both backing types. The repeated use of products A and B decreased the tensile strength of the carpet backing, while use of product B resulted in cracks on carpet fibers. Overall, steam treatment for 15 seconds was efficacious on both carpet types, but only product B achieved efficacy after a 30-minute exposure on the carpet with waterproof backing.IMPORTANCECarpets are common in long-term care facilities, despite its potential as a vehicle for transmission of agents associated with healthcare-associated infections, including human norovirus (NoV). Presently, our understanding of carpet disinfection is limited; hence, there are no commercial antimicrobials against norovirus available for use on carpets. Our findings showed that steam treatment, which minimally affected the properties of carpet fibers and backing, was more efficacious against human norovirus surrogates on carpets compared to the three chemical antimicrobials tested. Additionally, the two surrogates were more sensitive to chemical antimicrobials on the carpet with waterproof backing compared to carpets with water-permeable backing. These findings can inform development of antimicrobials for use on carpets contaminated with human norovirus.

Persistence of two coronaviruses and efficacy of steam vapor disinfection on two types of carpet.

BACKGROUND: Coronaviruses, a group of highly transmissible and potentially pathogenic viruses, can be transmitted indirectly to humans via fomites. To date, no study has investigated their persistence on carpet fibers. Establishing persistence is essential before testing the efficacy of a disinfectant. METHODS: The persistence of BCoV and HCoV OC43 on polyethylene terephthalate (PET) and nylon carpet was first determined using infectivity and RT-qPCR assays. Then, the disinfectant efficacy of steam vapor was evaluated against both coronaviruses on nylon carpet. RESULTS: Immediately after inoculation of carpet coupons, 32.50% of BCoV and 3.87% of HCoV OC43 were recovered from PET carpet, compared to 34.86% of BCoV and 24.37% of HCoV OC43 recovered from nylon carpet. After incubation at room temperature for 1 h, BCoV and HCoV OC43 showed a 3.6 and > 2.8 log10 TCID50 reduction on PET carpet, and a 0.6 and 1.8 log10 TCID50 reduction on nylon carpet. Based on first-order decay kinetics, the whole gRNA of BCoV and HCoV OC43 were stable with k values of 1.19 and 0.67 h- 1 on PET carpet and 0.86 and 0.27 h- 1 on nylon carpet, respectively. A 15-s steam vapor treatment achieved a > 3.0 log10 TCID50 reduction of BCoV and > 3.2 log10 TCID50 reduction of HCoV OC43 on nylon carpet. CONCLUSION: BCoV was more resistant to desiccation on both carpet types than HCoV OC43. Both viruses lost infectivity quicker on PET carpet than on nylon carpet. Steam vapor inactivated both coronaviruses on nylon carpet within 15 s.

Deciphering the Mechanism of Action of the Antimicrobial Peptide BP100.

The linear undecapeptide KKLFKKILKYL-NH2 (BP100) highlights for its antibacterial activity against Gram-negative bacteria and its low toxicity. These excellent biological properties prompted the investigation of its mechanism of action, which were undertaken using spectroscopic techniques, biophysical analysis, microscopy, and molecular dynamic simulations. Studies were conducted in different membrane environments, such as anionic, zwitterionic, and mixed membranes, as well as in vesicles (LUVs and GUVs) and bacteria. The findings suggest that BP100 exhibits a preference for anionic membranes, and its mechanism of action involves charge neutralization and membrane permeabilization. In these membranes, BP100 transitions from an unstructured state in water to an α-helix with the axis parallel to the surface. MD simulations suggest that after electrostatic interaction with the membrane, BP100 flips, facilitating the insertion of its hydrophobic face into the membrane bilayer. Thus, BP100 adopts an almost vertical transmembrane orientation with lysine side chains snorkelling on both sides of the membrane. As a result of the rotation, BP100 induces membrane thinning and slow lipid diffusion and promotes water penetration, particularly in anionic lipid membranes. These investigations pointed towards a carpet-like mechanism and are aligned with the biological activity profile described for BP100. This review covers all the studies carried out on the mechanism of action of BP100 published between 2009 and 2023.

Comparison of auditory evoked potential thresholds in three shark species.

Auditory sensitivity measurements have been published for only 12 of the more than 1150 extant species of elasmobranchs (sharks, skates and rays). Thus, there is a need to further understand sound perception in more species from different ecological niches. In this study, the auditory evoked potential (AEP) technique was used to compare hearing abilities of the bottom-dwelling New Zealand carpet shark (Cephaloscyllium isabellum) and two benthopelagic houndsharks (Triakidae), the rig (Mustelus lenticulatus) and the school shark (Galeorhinus galeus). AEPs were measured in response to tone bursts (frequencies: 80, 100, 150, 200, 300, 450, 600, 800 and 1200 Hz) from an underwater speaker positioned 55 cm in front of the shark in an experimental tank. AEP detection thresholds were derived visually and statistically, with statistical measures slightly more sensitive (∼4 dB) than visual methodology. Hearing abilities differed between species, mainly with respect to bandwidth rather than sensitivity. Hearing was least developed in the benthic C. isabellum [upper limit: 300 Hz, highest sensitivity: 100 Hz (82.3±1.5 dB re. 1 µm s-2)] and had a wider range in the benthopelagic rig and school sharks [upper limit: 800 Hz; highest sensitivity: 100 Hz (79.2±1.6 dB re. 1 µm s-2) for G. galeus and 150 Hz (74.8±1.8 dB re. 1 µm s-2) for M. lenticulatus]. The data are consistent with those known for 'hearing non-specialist' teleost fishes that detect only particle motion, not pressure. Furthermore, our results provide evidence that benthopelagic sharks exploit higher frequencies (max. 800 Hz) than some of the bottom-dwelling sharks (max. 300 Hz). Further behavioural and morphological studies are needed to identify what ecological factors drive differences in upper frequency limits of hearing in elasmobranchs.

Toxic effect of carpet dust on the biochemical indices and histological structure of the lung in rats: the potential role of cytochrome P450 2E1 and extracellular signal-regulated kinase/mitogen-activated protein kinase pathways.

Background: Carpet dust exposure in the carpet industry causes various respiratory hazards that lead to permanent loss of lung function. This study investigated the potentially toxic effects of knotted and tufted carpet dust on rat lungs and the possible involvement of cytochrome P450 2E1 (CYP2E1) and extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathways in the induced toxicity, as well as histological changes in the lung induced by carpet dust.Methods: This study divided 48 adult rats into six groups: group I was the control group, group II (vehicle group) received phosphate buffer saline (50 µL/rat), groups III and IV received knotted dust (2.5 and 5 mg/kg, respectively), and groups V and VI received tufted dust (2.5 and 5 mg/kg, respectively). All treatments were intranasally administered once a day for 7 days.Results: Both dust types significantly decreased the lung content of GSH compared with the control. Significantly elevated malondialdehyde (MDA) and nitric oxide (NO) lung contents were observed with an increased CYP2E1, interleukin (IL)-6, nuclear factor kappa B (NF-κß), and ERK/MAPK. The histological lung structure was moderately affected with a moderately increased number of CD68-positive macrophages in the lung parenchyma of knotted dust-exposed rats, whereas tufted dust exposure severely affected the lung tissue with significantly increased CD68-positive macrophages.Conclusions: Carpet dust exposure could induce oxidative stress and inflammatory response in the lung tissue via induction of CYP2E1 that stimulates ERK/MAPK signalling pathway proteins, resulting in elevated MDA, NO and IL-6 levels in the lung tissue with suppressed GSH content. Tufted dust could possess a more toxic response than knotted ones.

Calcium Carbonate in Waste Flooring for Neutralization of Acid Rock Drainage.

Acid rock drainage (ARD) was successfully neutralized in this study using carpet tiles. Most polyolefin-based carpet tiles contain over 65% of finely ground calcium carbonate (CaCO3) powder by weight in the compound-blended and extruded backing structure; therefore, using them for neutralization is an innovative way to reuse a difficult-to-recycle complex and abundant product. The overall neutralization efficiency potential was calculated at 40% based on the density, purity, and surface images that display the domains of CaCO3 on the tiles. The carpet backing increased the mean of proton activity of AMD collected from a single acidic stream point within the Pinkerton Run tributary near Pittsburgh, PA from 3.3 to 6.1 over the span of four hours in batch-method experiments at CaCO3 loading levels of 0.1 g/L and overall surface area exposure of 229 mm2/mL. Hot acidity levels decreased from 90 to less than 10 mg CaCO3/L, and below detection limits after 20 h of neutralization. The treated and neutralized AMD sample contained 80 mg/L more calcium than the untreated, non-neutralized control, demonstrating the dissolution of CaCO3 from the carpet tile.

En este estudio se utilizaron con éxito losetas de moqueta para neutralizar el drenaje ácido de roca (DAR). La mayoría de las losetas de moqueta a base de poliolefina contienen más de un 65% de polvo de carbonato de calcio (CaCO3) finamente molido en peso en la estructura de soporte extruida y mezclada con compuestos; su utilización para la neutralización es una forma innovadora de reutilizar un producto complejo y abundante y que es difícil de reciclar. El potencial de eficiencia de neutralización global es del 40% en base a su densidad, la pureza y las imágenes de superficie que muestran los dominios de CaCO3 en las losetas. El soporte de la moqueta incrementó la media de la actividad protónica del AMD recogido de un único punto de corriente ácida dentro del afluente Pinkerton Run, cerca de Pittsburgh, PA, de 3,3 a 6,1 en el transcurso de cuatro horas en experimentos por lotes con niveles de carga de CaCO3 de 0,1 g/L y una exposición global del área superficial de 229 mm²/mL. Niveles muy elevados de acidez disminuyeron de 90 mg CaCO3/L a menos de 10 mg CaCO3/L, y por debajo de los límites de detección tras 20 horas de neutralización. La muestra de AMD tratada y neutralizada contenía 80 mg/L más de calcio que el control no tratado y no neutralizado, lo que demuestra la disolución del CaCO3 de la loseta de moqueta.

Information Requirements under the Essential-Use Concept: PFAS Case Studies.

Per- and polyfluoroalkyl substances (PFAS) are a class of substances for which there are widespread concerns about their extreme persistence in combination with toxic effects. It has been argued that PFAS should only be employed in those uses that are necessary for health or safety or are critical for the functioning of society and where no alternatives are available ("essential-use concept"). Implementing the essential-use concept requires a sufficient understanding of the current uses of PFAS and of the availability, suitability, and hazardous properties of alternatives. To illustrate the information requirements under the essential-use concept, we investigate seven different PFAS uses, three in consumer products and four industrial applications. We investigate how much information is available on the types and functions of PFAS in these uses, how much information is available on alternatives, their performance and hazardous properties and, finally, whether this information is sufficient as a basis for deciding on the essentiality of a PFAS use. The results show (i) the uses of PFAS are highly diverse and information on alternatives is often limited or lacking; (ii) PFAS in consumer products often are relatively easy to replace; (iii) PFAS uses in industrial processes can be highly complex and a thorough evaluation of the technical function of each PFAS and of the suitability of alternatives is needed; (iv) more coordination among PFAS manufacturers, manufacturers of alternatives to PFAS, users of these materials, government authorities, and other stakeholders is needed to make the process of phasing out PFAS more transparent and coherent.

Understanding Ozone Transport and Deposition within Indoor Surface Boundary Layers.

Ozone-initiated oxidation reactions on indoor surfaces meaningfully alter the chemical composition of indoor air and human exposure to air toxins. Ozone mass transport within the indoor surface boundary layer plays a key role in ozone-surface reaction kinetics. However, limited information is available on detailed ozone transport dynamics near realistic, irregular indoor surfaces. This paper presents a research framework to study the underlying mechanisms of ozone reactions with realistic indoor surfaces based on microscope scanning of surface material and detailed Computational Fluid Dynamics (CFD) simulation. The study results show that indoor surface topography can meaningfully affect ozone mass transport within a surface boundary layer, thereby modulating near-surface ozone concentration gradient and surface uptake. The results also reveal that the effective indoor surface area available for ozone reaction varies with indoor air speed and turbulent air mixing within the boundary layer. The detailed dynamic behaviors of ozone reactions with realistic indoor surfaces provide insights into the implications of pollutant-surface interactions on indoor chemistry and air quality.

Organic Fluorine as an Indicator of Per- and Polyfluoroalkyl Substances in Dust from Buildings with Healthier versus Conventional Materials.

Per- and polyfluoroalkyl substances (PFAS) are a class of thousands of persistent, organic fluorinated chemicals added to materials and products mainly to repel stains and water. PFAS have been associated with many adverse human health effects. We aimed to determine whether buildings with "healthier" materials─defined here as reportedly free of all PFAS─exhibit lower PFAS in dust. In addition to analyzing targeted PFAS with available commercial standards, we measured extractable organic fluorine (EOF) as a novel proxy that includes both known and unknown types of PFAS. We measured at least 15 targeted PFAS (n = 24), EOF (n = 24), and total fluorine (TF; n = 14) in dust collected from university common spaces and classrooms, half of which had "healthier" furniture and carpet. We observed lower PFAS contamination in buildings with "healthier" materials: "healthier" rooms had a 66% lower median summed PFAS and a 49% lower Kaplan-Meier estimated mean EOF level in dust in comparison to conventional rooms. The summed targeted PFAS were significantly correlated with EOF but accounted for up to only 9% of EOF, indicating the likely presence of unidentified PFAS. EOF levels explained less than 1% of TF in dust. We emphasize the need to use chemical class-based methods (e.g., EOF) for evaluating class-based solutions and to expand non-PFAS solutions for other building materials.

A qualitative study on the health-seeking behavior and its determinants among carpet weavers in Kashmir.

We conducted this study to examine the nature of treatment-seeking behavior among carpet weavers in Kashmir. We used a grounded theory approach to gain an in-depth understanding of the phenomenon. Data were collected through face-to-face interviews with 35 research participants recruited through purposive and theoretical sampling techniques. Based on the primary data, our study reveals that carpet weavers approached different agencies and used multiple methods for seeking treatment for their illness(es). The majority of the participants relied on spiritual healers, followed by traditional methods, Unani treatment, compounders and self-medication, while modern medicine was the last option for seeking treatment. We also found that participants base their choices about when and where to seek treatment on multiple socio-economic and cultural factors like financial constraints, perception towards illness, no provision for leave, costly and lengthy medical treatment, side effects of modern medicine, the nature of the disease, lack of infrastructure and insecurity due to conflict. These findings are relevant to employers and various government as well as non-government organizations. Additional implications of these findings for carpet weavers, public health, for practice and research are also discussed.

A Dynamic RCS and Noise Prediction and Reduction Method of Coaxial Tilt-Rotor Aircraft Based on Phase Modulation.

For tilt-rotor aircraft with coaxial rotors (coaxial rotor aircraft), reduction of radar cross section as well as acoustic noise can be essential for stealth design, and the rotation of the coaxial rotors can have an influence on noise and dynamic radar cross section (RCS) characteristics. In this paper, an approach to the prediction of both the sound pressure level (SPL) of noise and the dynamic RCS of coaxial-tilt aircraft is carried out, based on the theories of the FW-H equation, the physics optics method (PO) and the physical theory of diffraction (PTD) method. In order to deal with the rotating parts (mainly including coaxial rotors), a generated rotation matrix (GRM) is raised, aiming at giving a universal formula for the time-domain grid coordinate transformation of all kinds of rotation parts with arbitrary rotation centers and rotation axis directions. Moreover, a compass-scissors model (CSM) reflecting the phase characteristics of coaxial rotors is established, and a method of noise reduction and RCS reduction based on the phase modulation method is put forward in this paper. The simulation results show that with proper CSM parameter combinations, the reduction of noise SPL can reach approximately 3~15 dB and the reduction of dynamic RCS can reach 1.6 dBsm at most. The dynamic RCS and noise prediction and reduction method can be meaningful for the radar-acoustic stealth design of coaxial tilt-rotor aircrafts.

Anthrenus sp. and an Uncommon Cluster of Dermatitis.

We report patients in their homes in France who had cutaneous lesions caused by Anthrenus sp. larvae during the end of winter and into spring. These lesions mimic bites but are allergic reactions to larvae hairs pegged in the skin. These lesions should be distinguished from bites of bed bugs or fleas.

The largest moss carpet transplant in Antarctica and its bryosphere cryptic biodiversity.

As part of the reconstruction of the Brazilian Antarctic Station on King George Island, three areas of moss carpet were transplanted to minimize the impact of the new facilities on the local biodiversity. A total of 650 m2 of moss carpet was transplanted to neighboring but previously uncolonized locations and has subsequently survived for the last 3 years. Antarctic moss carpets typically comprise low moss species diversity and are often monospecific. We investigated the cryptic biodiversity that was transplanted along with the carpets using a metabarcoding approach through high throughput sequencing. We targeted 16S rRNA for Bacteria and Archaea, ITS for Fungi and Viridiplantae and Cox1 for Metazoa. We detected DNA representing 263 taxa from five Kingdoms (Chromista, Fungi, Metazoa, Protista and Viridiplantae), two Domains (Archaea and Bacteria) and 33 Phyla associated with the carpet. This diversity included one Archaea, 189 Bacteria, 24 Chromista, 19 Fungi, eight Metazoa, seven Protista and 16 Viridiplantae. Bacteria was the most abundant, rich and diverse group, with Chromista second in diversity and richness. Metazoa was less diverse but second highest in dominance. This is the first study to attempt transplanting a significant area of moss carpet to minimize anthropogenic environmental damage in Antarctica and to use metabarcoding as a proxy to assess diversity associated with Antarctic moss carpets, further highlighting the importance of such habitats for other organisms and their importance for conservation.

Carpet beetle dermatitis mimicking bullous impetigo.

A 13-year-old female patient presented with a 3-month history of recurrent blisters, which ruptured into multiple superficial erosions with overlying crust located on the face, neck, and shoulder. Treatment for presumed bullous impetigo showed no benefit. Samples collected from the patient's home revealed the presence of numerous carpet beetles in a wool rug. Carpet beetle dermatitis resembles papular urticaria but may occasionally present as skin lesions resembling bullous impetigo.

Growth Kinetics of Two-Dimensional Hexagonal Boron Nitride Layers on Pd(111).

Using in situ variable-temperature scanning tunneling microscopy (300-673 K) during chemical vapor deposition of two-dimensional hexagonal boron nitride (hBN) on Pd(111) from borazine precursor at pressures up to 10-6 mbar, we identify the mechanisms leading to carpetlike uphill or downhill growth across the Pd steps. Deposition at a higher rate and lower temperature promotes uphill growth via preferential attachment at the ascending and descending step-edges, whereas a lower deposition rate and higher temperature lead to downhill growth via nucleation and growth of islands on Pd terraces. We attribute this unusual growth behavior to differences in temperature-dependent rates of hBN deposition at the steps versus on the Pd terraces. Our results illustrate how growth mechanisms can be activated by a pair of parameters (substrate temperature and partial pressure of borazine) and provide new insights into the mechanisms underlying carpetlike growth of hBN and other layered materials.

Modeling microbial growth in carpet dust exposed to diurnal variations in relative humidity using the "Time-of-Wetness" framework.

Resuspension of microbes in floor dust and subsequent inhalation by human occupants is an important source of human microbial exposure. Microbes in carpet dust grow at elevated levels of relative humidity, but rates of this growth are not well established, especially under changing conditions. The goal of this study was to model fungal growth in carpet dust based on indoor diurnal variations in relative humidity utilizing the time-of-wetness framework. A chamber study was conducted on carpet and dust collected from 19 homes in Ohio, USA and exposed to varying moisture conditions of 50%, 85%, and 100% relative humidity. Fungal growth followed the two activation regime model, while bacterial growth could not be evaluated using the framework. Collection site was a stronger driver of species composition (P = 0.001, R2  = 0.461) than moisture conditions (P = 0.001, R2  = 0.021). Maximum moisture condition was associated with species composition within some individual sites (P = 0.001-0.02, R2  = 0.1-0.33). Aspergillus, Penicillium, and Wallemia were common fungal genera found among samples at elevated moisture conditions. These findings can inform future studies of associations between dampness/mold in homes and health outcomes and allow for prediction of microbial growth in the indoor environment.

Membrane Permeabilization Mechanisms.

Many antimicrobial peptides are considered to kill microbes by permeabilizing cell membranes. This chapter summarizes the driving force of peptide binding to membranes; various mechanisms of lipid bilayer permeabilization including the barrel-stave, toroidal pore, and carpet models; and modes of permeabilization of bacterial and mammalian membranes.

The Mechanisms of Action of Cationic Antimicrobial Peptides Refined by Novel Concepts from Biophysical Investigations.

Even 30 years after the discovery of magainins, biophysical and structural investigations on how these peptides interact with membranes can still bear surprises and add new interesting detail to how these peptides exert their antimicrobial action. Early on, using oriented solid-state NMR spectroscopy, it was found that the amphipathic helices formed by magainins are active when being oriented parallel to the membrane surface. More recent investigations indicate that this in-planar alignment is also found when PGLa and magainin in combination exert synergistic pore-forming activities, where studies on the mechanism of synergistic interaction are ongoing. In a related manner, the investigation of dimeric antimicrobial peptide sequences has become an interesting topic of research which bears promise to refine our views how antimicrobial action occurs. The molecular shape concept has been introduced to explain the effects of lipids and peptides on membrane morphology, locally and globally, and in particular of cationic amphipathic helices that partition into the membrane interface. This concept has been extended in this review to include more recent ideas on soft membranes that can adapt to external stimuli including membrane-disruptive molecules. In this manner, the lipids can change their shape in the presence of low peptide concentrations, thereby maintaining the bilayer properties. At higher peptide concentrations, phase transitions occur which lead to the formation of pores and membrane lytic processes. In the context of the molecular shape concept, the properties of lipopeptides, including surfactins, are shortly presented, and comparisons with the hydrophobic alamethicin sequence are made.

Effectiveness of indoor allergen reduction in asthma management: A systematic review.

BACKGROUND: This review will inform updated National Asthma Education and Prevention Program clinical practice guidelines. OBJECTIVE: We sought to evaluate the effectiveness of allergen reduction interventions on asthma outcomes. METHODS: We systematically searched the "gray literature" and 5 bibliographic databases. Eligible studies included systematic reviews, randomized controlled trials, and nonrandomized interventional studies. Risk of bias was assessed by using the Cochrane Risk of Bias instrument and the Newcastle-Ottawa scale. The evidence base was assessed by using the approach of the Agency for Healthcare Research and Quality's Evidence-based Practice Center program. RESULTS: Fifty-nine randomized and 8 nonrandomized trials addressed 8 interventions: acaricide, air purification, carpet removal, high-efficiency particulate air filtration (HEPA) vacuums, mattress covers, mold removal, pest control, and pet removal. Thirty-seven studies evaluated single-component interventions, and 30 studies assessed multicomponent interventions. Heterogeneity precluded meta-analysis. For most interventions and outcomes, the evidence base was inconclusive or showed no effect. No interventions were associated with improvement in validated asthma control measures or pulmonary physiology. Exacerbations were diminished in multicomponent studies that included HEPA vacuums or pest control (moderate strength of evidence [SOE] for both). Quality of life improved in studies of air purifiers (SOE: low) and in multicomponent studies that included HEPA vacuums (SOE: moderate) or pest control (SOE: low). CONCLUSIONS: Single interventions were generally not associated with improvement in asthma measures, with most strategies showing inconclusive results or no effect. Multicomponent interventions improved various outcomes, but no combination of specific interventions appears to be more effective. The evidence was often inconclusive because of a lack of studies. Further research is needed comparing the effect of indoor allergen reduction interventions on validated asthma measures, with sufficient population sizes to detect clinically meaningful differences.

Ten questions concerning the implications of carpet on indoor chemistry and microbiology.

Carpet and rugs currently represent about half of the United States flooring market and offer many benefits as a flooring type. How carpets influence our exposure to both microorganisms and chemicals in indoor environments has important health implications but is not well understood. The goal of this manuscript is to consolidate what is known about how carpet impacts indoor chemistry and microbiology, as well as to identify the important research gaps that remain. After describing the current use of carpet indoors, questions focus on five specific areas: 1) indoor chemistry, 2) indoor microbiology, 3) resuspension and exposure, 4) current practices and future needs, and 5) sustainability. Overall, it is clear that carpet can influence our exposures to particles and volatile compounds in the indoor environment by acting as a direct source, as a reservoir of environmental contaminants, and as a surface supporting chemical and biological transformations. However, the health implications of these processes are not well known, nor how cleaning practices could be optimized to minimize potential negative impacts. Current standards and recommendations focus largely on carpets as a primary source of chemicals and on limiting moisture that would support microbial growth. Future research should consider enhancing knowledge related to the impact of carpet in the indoor environment and how we might improve the design and maintenance of this common material to reduce our exposure to harmful contaminants while retaining the benefits to consumers.