Fungal biodetector: a real-time indoor air quality monitoring

International audienceFungi are common biocontaminants of indoor environments, and numerous studies have demonstrated how they can degrade the materials they colonise (e.g. wood, textiles, paper, pigments, varnishes, etc.), which can even result in total destruction of these substrates. Today, fungal contamination is an increasing problem in houses, working places, schools, hospitals, elderly care centers and cultural heritage. Current techniques are unable to detect mould at an early stage in their development or hidden contaminants. Moularat et al. (2008) has established chemical fingerprints of mouldy development from Volatile Organic Compounds (VOCs) arising specifically from fungal metabolism. This approach has the advantage of detecting fungal development both reliably and rapidly before any visible signs of contamination could be detected. Since the development of this Fungal Contamination Index (FCI), other specific indexes have been developed to monitor Invasive Nosocomial Aspergillosis in hospitals or Serpula Lacrymans in dwellings. Their applications constitute a new approach for diagnosis. However, even if the FCI has been widely tested, VOCs'analysis by GC/MS, which is required for index calculation, is incompatible for indoor environment real-time monitoring strategy. So having such a device, which could be set up in buildings and able to provide almost instantaneous information on prospective fungal development, constitutes a breakthrough. In this context, researches around FCI exploitation have been followed up in order to provide a device widely deployable which enables mould development real-time monitoring. This innovative microsystem is the result of the miniaturization of an analytical chain for portable, reliable and low-cost applications. This biodetector was the subject of patent applications by the CSTB

Resistance of aerosolized bacterial viruses to four germicidal products

Viral diseases can spread through a variety of routes including aerosols. Yet, limited data are available on the efficacy of aerosolized chemicals to reduce viral loads in the air. Bacteriophages (phages) are often used as surrogates for hazardous viruses in aerosol studies because they are inexpensive, easy to handle, and safe for laboratory workers. Moreover, several of these bacterial viruses display physical characteristics similar to pathogenic human and animal viruses, like morphological size, type of nucleic acids, capsid morphology, and the presence of an envelope. In this study, the efficacy of four chemicals was evaluated on four airborne phages at two different relative humidity levels. Non-tailed bacteriophages MS2 (single-stranded RNA), ϕ6 (double-stranded RNA, enveloped), PR772 (double-stranded DNA), and ϕX174 (single-stranded DNA) were first aerosolized in a 55L rotative environmental chamber at 19°C with 25% and 50% relative humidity. Then, hydrogen peroxide, Eugenol (phenylpropene used in commercial perfumes and flavorings), Mist® (automobile disinfectant containing Triethylene glycol), and Pledge® (multisurface disinfectant containing Isopropanol, n-Alkyl Dimethyl Benzyl Amonium Chlorides, and n-Alkyl Dimethyl Ethylbenzyl Ammonium Chloride) were nebulized with the phages using a separate nebulizer. Aerosols were maintained in suspension during 10 minutes, 1 hour, and 2 hours. Viral aerosols were sampled using an SKC BioSampler and samples were analyzed using qPCR and plaque assays. The resistance levels of the four phages varied depending on the relative humidity (RH) and germicidal products tested. Phage MS2 was the most stable airborne virus under the environmental conditions tested while phage PR772 was the least stable. Pledge® and Eugenol reduced the infectivity of all airborne phages tested. At 25% RH, Pledge® and Eugenol were more effective at reducing infectivity of RNA phages ϕ6 and MS2. At 50% RH, Pledge® was the most effective agent against phage MS2. These findings illustrate that various airborne viruses should be tested to demonstrate the effectiveness of germicidal treatments. This research also provides a set of parameters for testing germicidal products in large-scale settings to reduce the risk of virus transmission

Numerical modelling of microorganisms dispersion in urban area : application to legionella

International audienceDispersion modelling is often used to estimate potentially contaminated areas in case of accidental release of microorganisms in the atmosphere. In the specific case of Legionella, accidental spread in the atmosphere due to contaminated cooling towers system may occur over distance larger than 10km. In addition, most cooling towers are located in urban areas where dispersion due to obstacles is complex. In this case, dispersion models have to take into account complex flows and microphysical processes that occur within the plume and may have an impact on the survival of the microorganisms. To estimate the concentration of microorganisms in these areas, a specific module has been developed within the lagrangian dispersion model Micro Swift Spray (MSS, Aria technologies). This module takes into account microorganisms outside or inside water liquid droplets and microphysical interaction inside the plume. A simple biological module governing the survival of airborne microorganisms has also been implemented in the dispersion model

A new approach to detect early or hidden fungal development in indoor environments

International audienceIn addition to the biodegradation problems encountered in buildings, exposure of their occupants to mold is responsible for numerous diseases such as respiratory infections, immediate or delayed allergies and different types of irritations. However, current techniques are unable to detect mold at an early stage of development or hidden contaminants.Moularat et al., in 2008 has established chemical fingerprints of moldy growth from Volatile Organic Compounds (VOCs) arising specifically from fungal metabolism and developed the Fungal Contamination Index (FCI) (Moularat et al., 2008a,b). This index has the advantage of detecting fungal development both reliably and rapidly before any visible signs of contamination could be detected.However, even though the FCI has been widely tested, VOCs’ analysis by GC/MS, which is required for index calculation, is incompatible with real-time monitoring strategy for indoor environments.In this context, researches around FCI exploitation have been followed up in order to provide a monitoring device widely deployable which is the result of the miniaturization of an analytical chain for portable, reliable and low-cost applications. This device is based on one hand the selection and concentration of chemical compounds from the sample of interest and on the other hand the development of an array of different conducting polymer based sensors in order to obtain a specific footprint.This fungal contamination detection device was the subject of patent applications by the CSTB.The modularity of the system (ability to vary both the elements of detection polymers and retention time of interest) allows for expansion of its use to other pollutants

Monitoring beacon for early or hidden fungal development detection dedicated to heritage conservation

International audienc

Fungal biodetector: a real-time indoor air quality monitoring

International audienceFungi are common biocontaminants of indoor environments, and numerous studies have demonstrated how they can degrade the materials they colonise (e.g. wood, textiles, paper, pigments, varnishes, etc.), which can even result in total destruction of these substrates. Today, fungal contamination is an increasing problem in houses, working places, schools, hospitals, elderly care centers and cultural heritage. Current techniques are unable to detect mould at an early stage in their development or hidden contaminants. Moularat et al. (2008) has established chemical fingerprints of mouldy development from Volatile Organic Compounds (VOCs) arising specifically from fungal metabolism. This approach has the advantage of detecting fungal development both reliably and rapidly before any visible signs of contamination could be detected. Since the development of this Fungal Contamination Index (FCI), other specific indexes have been developed to monitor Invasive Nosocomial Aspergillosis in hospitals or Serpula Lacrymans in dwellings. Their applications constitute a new approach for diagnosis. However, even if the FCI has been widely tested, VOCs'analysis by GC/MS, which is required for index calculation, is incompatible for indoor environment real-time monitoring strategy. So having such a device, which could be set up in buildings and able to provide almost instantaneous information on prospective fungal development, constitutes a breakthrough. In this context, researches around FCI exploitation have been followed up in order to provide a device widely deployable which enables mould development real-time monitoring. This innovative microsystem is the result of the miniaturization of an analytical chain for portable, reliable and low-cost applications. This biodetector was the subject of patent applications by the CSTB

Monitoring beacon for early or hidden fungal development detection dedicated to heritage conservation

International audienc

Assessing bactericidal properties of materials the case of metallic surfaces in contact with air

Abstract A new method for assessing bactericidal properties of metallic materials, soiled by aerosol, was developed and applied to stainless steel in conditions close to reality. The airborne bacteria survival on different stainless steel grades and massive copper is presented here. The investigating bacterium was Enterococcus faecalis, which is a well-known contaminant strain in the indoor environments. It was observed that the bacterial aerosol lethality increased proportionally with the relative humidity (RH) of the environment. A significant difference in survival rate was measured depending on the tested supports, the greatest lethality being observed on clean massive copper. Moreover, the addition of nutrients on metallic surfaces, even in small quantities, was enough to ensure the revival of quiescent microorganisms.

A voluntary evaluation scheme of the environmental and health-based characteristics of building products in France

International audienceSince there was almost no information available in France on the environmental properties and on the emissions to indoor air of building products placed on the market, CSTB proposed a global evaluation scheme of the environmental and health-based characteristics of building products. This evaluation scheme has been introduced in France in 2003, on a voluntary basis, as a complement of the Technical Agreement procedure (Avis Technique in French) for the evaluation of the fit for use properties of building product

Characterization of Airborne Legionella Exposure

International audienc