Decontamination of room air and adjoining wall surfaces by nebulizing hydrogen peroxide

Aim: In 2010, the ASP GLOSAIR^TM 400 was introduced in Germany for nebulizing hydrogen peroxide (H₂O₂). Since there were no results of practical experience, the new method was to be checked under practical conditions for its effectiveness in decontaminating air in rooms, infested with mold after water damage and, at the same time, under experimentally controlled conditions, test surfaces, contaminated with Aspergillus brasiliensis.Method: After the nebulizer was used in two rooms with a massive mold infestation, the air colony count was determined (MAS-100^® Zinsser Analytik) and, at the same time, the mold infestation in samples of wall plaster.As part of this controlled study, test surfaces contaminated with Aspergillus brasiliensis were positioned vertically and horizontally in a test room. The effectiveness of the nebulization (5–6% H₂O₂ for 2 hours) was tested on these surfaces according to EN 13697.Results: In a massive mold infestation resulting from water damage (worst case), an approximately 9-fold decrease in the mold content and an approximately 13-fold decrease in the number of colony-forming units (sum of the bacteria + fungi) could be detected in the room air immediately after the nebulizing was finished. Even in samples of wall and joint plaster, the molds were reduced, although to a distinctly lesser extent. By indoor nebulization of 5–6% H₂O₂, A. brasiliensis was reduced >4 log on vertical and horizontal surfaces.Discussion: In rooms with a massive mold infestation, the ASP GLOSAIR^TM 400 system is suitable for attaining a clear reduction in the fungal and bacterial room air load, lasting for a week. On vertical and horizontal surfaces, contaminated experimentally with A. brasiliensis, a reduction of >4 lg is achieved. As a load of 10⁴ to 10⁵ fungal spores is unlikely to occur on pre-cleaned surfaces, the GLOSAIR^TM 400 can be considered a suitable complementary process for the substantial reduction of fungal contamination.     

Phytoextraction and phytoexcretion of Cd by the leaves of Tamarix smyrnensis growing on contaminated non-saline and saline soils

Phytoremediation and more specifically phytoextraction, is an alternative restoration strategy for the clean up of heavy metal contaminated soils. Phytoextraction can only be successful if suitable plant species colonize the contaminated area, extract the toxic substances and accumulate them in their above ground tissues. In this study, the salt cedar Tamarix smyrnensis that is a widespread salt-tolerant plant in the Mediterranean region has been investigated. A pot experiment is conducted with T. smyrnensis grown in polluted soil with 16ppm of cadmium and at three different salt concentrations (0.0, 0.5, 3.0% NaCl) for a 10-week period. It took place in an open-air area with natural light, at ambient temperature and humidity in an effort to keep the plants under conditions as similar as possible to those in the field. However, care was taken not to let them be rained on. Temperature ranged from 19 to 50 degrees C with 33 and 21 degrees C being the average day and night temperature, respectively. Humidity ranged from 28% to 87% with a 13-14h photoperiod. The specific aims of this work are to investigate the accumulation of cadmium via root uptake at different saline conditions and cadmium excretion through salt glands on the surface of the leaves as a probable detoxification mechanism of the plant. Furthermore, measurements of chlorophyll content, biomass, and shoot length are used to evaluate the potential of the plant for the removal of cadmium from contaminated saline and non-saline soils. The experimental data suggest that increased soil salinity results in an increase of the cadmium uptake by T. smyrnensis. Analysis of white salt crystals taken from glandular tissue confirmed the fact that this plant excretes cadmium through its salt glands on the surface of the leaves as a possible detoxification mechanism in order to resist metal toxicity. Excreted cadmium is again released into the environment and it is redeposited on the top soil. Furthermore, increased salinity results in an increased excretion of the metal on Tamarix leaf surface. The presence of metals usually affects negatively the plant health, but T. smyrnensis developed no visible signs of metal toxicity, only salt toxicity symptoms were observed. Cadmium usually decreases the chlorophyll content in plants; however, the amount of photosynthetic pigments of T. smyrnensis was found not to be affected. All the above points to the potential of T. smyrnensis for use in phytoremediation with the metal secretion from the leaves being a unique advantage that may change current phytoextraction practices.     

External exposure to radionuclides accumulated in shoreline sediments with an application to the lower Clinch River

A simple analytical method was developed to estimate external doses from exposure to contaminated riverine shorelines. The method consists of deriving an adjustment factor that accounts for the geometry of the riverine shoreline; the adjustment factor is applied to the dose-rate coefficients already available for infinite contaminated surfaces. Such a geometry factor circumvents very complex radiation transport calculations which would otherwise be necessary to model exposures to a finite contaminated surface. For instance, for radionuclides emitting gamma rays of energies above 600 keV (e.g., 137Cs), the published dose-rate coefficients must be reduced by 75%, 60%, 50%, and 33% for shoreline widths of 4, 10, 20, and 50 m, respectively. The geometry factor changes only mildly with the energy of the gamma radiation. This property allows for the geometry factor to be used for radionuclides emitting multiple gamma rays of various energies. If a quick analysis is desired, the geometry factors derived for 137Cs can be used for all radionuclides. More refined analysis can be performed by deriving geometry factors for each radionuclide according to its gamma spectrum. Also, the mild variation with energy allows the geometry factors to be applied to the case when radionuclides are accumulated in layers under the soil surface, and not only to the case when radionuclides are deposited onto the soil surface. Empirical relationships between the geometry factor and the dimension of the shoreline were provided so that one can obtain values of the geometry factor for any shoreline width. These relationships can be easily used to account for the uncertainty in the dimension of the shoreline. The method was applied to derive similar adjustment factors for contaminated surfaces of other simple geometries (e.g., circular surfaces). An example of how this method can be applied to its full extent is presented for the case of external exposure to the shores of the lower Clinch River. This river received large amounts of 137Cs, 60Co, 106Ru, 95Zr, 95Nb, 144Ce, and 90Sr released during 1944-1991 from the Oak Ridge Reservation in Oak Ridge, Tennessee.     

一种医用空气消毒器消毒效果观察

目的观察一种医用空气消毒器对室内空气消毒效果。方法 用多级空气微生物采样器方法进行实验室和现场试验检测。结果该医用空气消毒器运行60 min对气雾室空气中白色葡萄球菌的杀菌率为99.96%;实验室空气中的自然消亡率≤52.28%。在内科监护室正常工作时运行60 min、120 min、180 min,对室内流动空气中的自然菌清除率达90.4%、92.2%和93.5%。结论 该医用空气消毒器在规定使用条件下,对实验室和在有人条件下对医院内科监护室中细菌有良好的清除效果,达到规范要求标准。     

Radiation effects of the Chernobyl accident on the Hungarian population

Due to the nuclear accident at Chernobyl in April 1986, the atmospheric transport spread the released radioactivity throughout the whole Europe. The initial plume moved into the north-western direction and a portion of this plum turned to west and later on to south-west. The central European countries including Hungary became affected in 29-30 April. The release during the last period (5-7 May) was directed to Romania, Bulgaria and Greece. In addition to the main trajectories of the atmospheric transport, the local meteorological conditions with winds of different directions at various altitudes, rainfalls etc. produced a very complex deposition pattern in Central Europe. The contamination of the soil surface and vegetation were strongly influenced by the wash-out of the radioactive materials from the local air. Due to the high geographical variation of the rains the surface contamination provided a similar heterogeneity among the territories of the country. The northern-west part and the region of the capital Budapest became nearly 5 times higher contaminated than the middle part of the country. Radiation doses of the population have been provided by activity concentrations in air, soil, vegetation, foods etc. and the external dose rates, mainly due to the surface contamination by the isotopes of 131I, 134Cs and 137Cs. The average effective dose contribution received by the individuals (adults) in Hungary during the 15 years following the accident has been assessed to be 0.30 mSv while the annual dose from the natural background is 2.5-3 mSv. Contribution to total dose from the internal pathway (committed effective dose) resulted about 0.10 mSv and the external radiation provided 0.19 mSv. The contributions of the external exposure from the contaminated air and inhalation are less than 5% of the total one.     

Use of a single method in the extraction of the seed storage globulins from several legume species. Application to analyse structural comparisons within the major classes of globulins

In this study, a single, improved methodology was used to extract, fractionate and purify the 11S (legumin-type or related to the alpha-conglutin from Lupinus albus L.), 7S (vicilin-type or related to the beta-conglutin from L. albus) and 2S (related to the gamma-conglutin from L. albus) families of proteins from eight legume species: L. albus, Glycine max (L.) Merr., Pisum sativum L., Vicia faba L., Cicer arietinum L., Phaseolus vulgaris L., Lens culinaris Med. and Arachis hypogaea L. The sedimentation coefficients obtained varied from 1.9 to 8.1 for the gamma-conglutin-related proteins, from 5.1 to 10.5 for the beta-conglutin-related proteins and from 12.0 to 14.9 for the alpha-conglutin-related globulins. The gamma-conglutin-related proteins is the most heterogeneous group. Antibodies produced against each type of gamma-conglutin polypeptide chain recognize the other polypeptide chain as well as other polypeptides in the corresponding globulins from all species examined. The 7S globulins are typically composed of a large number of polypeptides, covering a wide range of molecular masses (10 to 70 kD). The presence of disulphide bonds is apparently absent and the occurrence of glycopolypeptides is not widespread. Finally, the 11S globulins are characteristically formed by a limited number of polypeptides that may be divided into a lighter group (20-25 kD) and a heavier group (35-50 kD). The presence of disulphide bonds is apparently widespread but the occurrence of glycopolypeptides seems to be relatively rare. Both the 7S family and the 11S globulins studied by immunoblotting exhibit a low level of structural similarity.     

Electrocuting and electronic insect traps: Trapping efficiency and production of airborne particles

Five electrocuting insect traps were evaluated for their efficiency in eliminating house flies and moths from small premises, and for their production of insect fragments and airborne particles. An electronic trap which kills attracted insects by trapping them on a sticky surface was also included in the study. Airborne particles from the vicinity of traps in operation were collected on microporous filters. All traps performed equally in killing flies and moths. Although numerous moth scales were collected in the air filtrates when the moths were released in the rooms while all traps were off, their numbers increased when traps were turned on. The number of scale fragments significantly increased when electrocuting traps were used, but not with the electronic trap. Numerous spherical particles (diam. < 10 μm) were also collected in air filtrates near electrocuting traps killing moths. In addition to elements found in moths (P, K, Cl, S, Si), particles contained one or more of the metals Zn, Fe, and Cu. The metals in these particles and observed changes of the surface of used grid wires indicated that these spherical particles probably are solidified haemolymph and other body fluids, expelled from the moths as they are heated during electrocution. The generation of airborne particles is important because, in addition to the concerns for food contamination, most insect particles are potential allergens.     

Swimming pools and fungi: an environmental epidemiology survey in Italian indoor swimming facilities

A growing number of people attend swimming facilities for recreational activities, rehabilitative treatments, or sport. Filamentous fungi and yeast can be isolated from contaminated air, water and surfaces and may represent a biological risk for employees and users. Here we investigated the occurrence of mycotic species, in a sample of Italian swimming pools (n = 10). Detection and identification of isolated species were achieved by cultural and morphological methods. Results revealed moderate mycotic titres and a high biodiversity. Penicillium spp., Aspergillus spp., Cladosporium spp. and Alternaria sp., were constantly detected in air and surfaces sampled by the swimming area, while pathogenic yeast Candida albicans was never detected. Fusarium spp. was the most common taxon isolated from surfaces. For one facility, we typed the genotypic profiles and studied, by genetic typing, the spatial and temporal distribution of isolates. Phylogenetic relationships between species were analysed by alignment of small ribosomal subunit RNA sequences.     

Correlation between the prevalence of certain fungi and sick building syndrome

OBJECTIVE: To examine the role of fungi in the production of sick building syndrome. METHODS: A 22 month study in the United States of 48 schools (in which there had been concerns about health and indoor air quality (IAQ). Building indoor air and surface samples, as well as outdoor air samples were taken at all sites to look for the presence of fungi or their viable propagules. RESULTS: Five fungal genera were consistently found in the outdoor air and comprised over 95% of the outdoor fungi. These genera were Cladosporium (81.5%), Penicillium (5.2%), Chrysosporium (4.9%), Alternaria (2.8%), and Aspergillus (1.1%). At 20 schools, there were significantly more colony forming units per cubic metre (CFU/m3) (p < 0.0001) of propagules of Penicillium species in the air samples from complaint areas when compared with the outdoor air samples and the indoor air samples from noncomplaint areas. At five schools, there were more, although not significant (p = 0.10), Penicillium propagules in the air samples from complaint areas when compared with the outdoor air samples and the indoor air samples from noncomplaint areas. In 11 schools, the indoor air (complaint areas) fungal ratios were similar to that in the outdoor air. In these 11 schools Stachybotrys atra was isolated from swab samples of visible growth under wetted carpets, on wetted walls, or behind vinyl wall coverings. In the remaining 11 schools, the fungal ratios and CFU/m3 of air were not significantly different in different areas. Many of the schools took remedial action that resulted in an indoor air fungal profile that was similar to that outdoors. CONCLUSIONS: Propagules of Penicillium and Stachybotrys species may be associated with sick building syndrome.

 

     

Characterization of paint dust aerosol generated from mechanical abrasion of TiO2-containing paints

The purpose of the study was to determine the potential for release of titanium dioxide nanoparticles in paint dust. The coatings aerosol resuspension system was developed and used for testing the generation and physical, chemical, and morphological properties of paint dust particles from mechanical abrasion (i.e., sanding) of coated wood surfaces. The paint dust emissions from bare and coated wood surfaces with multiple coatings using variable sandpaper grits were evaluated. Substantially higher particle number concentrations were measured for paint dust containing particles in the nano range (particles with aerodynamic diameter less than 100?nm) than those measured for wood dust. The variability of particle number concentration and size distribution of paint dust derived under different conditions indicated that considerable quantities of nanoparticles might be released from mechanical abrasion of painted surfaces that may induce unhealthy exposure conditions. Moreover, spectroscopic and microscopic analysis identified the presence of paint and wood components in paint dust, including titanium dioxide agglomerates that were originally embedded in the paint. The agglomerates were mostly attached to particles with sizes <100?nm, enabling them to potentially penetrate into the lower respiratory tract. These results demonstrated that the paint dust exposure generation system can provide qualitative and quantitative information on particle emissions and the abundance of nanoparticles from paint sanding in realistic conditions and they may be used to assess occupational and environmental exposures and risks. Furthermore, the prevalence of titanium dioxide nanoparticles in paint dust highlights the potential for exposures of painters and other occupational groups to hazardous paint dust and the need for protective devices and strategies aiming to reduce exposures to nanoparticles.     

Environmental contamination makes an important contribution to hospital infection

Meticillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are capable of surviving for days to weeks on environmental surfaces in healthcare facilities. Environmental surfaces frequently touched by healthcare workers are commonly contaminated in the rooms of patients colonized or infected with MRSA or VRE. A number of studies have documented that healthcare workers may contaminate their hands or gloves by touching contaminated environmental surfaces, and that hands or gloves become contaminated with numbers of organisms that are likely to result in transmission to patients. Pathogens may also be transferred directly from contaminated surfaces to susceptible patients. There is an increasing body of evidence that cleaning or disinfection of the environment can reduce transmission of healthcare-associated pathogens. Because routine cleaning of equipment items and other high-touch surfaces does not always remove pathogens from contaminated surfaces, improved methods of disinfecting the hospital environment are needed. Preliminary studies suggest that hydrogen peroxide vapour technology deserves further evaluation as a method for decontamination of the environment in healthcare settings.     

Methamphetamine Residue Dermal Transfer Efficiencies from Household Surfaces

Methamphetamine contamination from illegal production operations poses a potential health concern for emergency responders, child protective services, law enforcement, and children living in contaminated structures. The objective of this study was to evaluate dermal transfer efficiencies of methamphetamine from contaminated household surfaces. These transfer efficiencies are lacking for methamphetamine, and would be beneficial for use in exposure models. Surfaces were contaminated using a simulated smoking method in a stainless steel chamber. Household surfaces were carpet, painted drywall, and linoleum. Dermal transfer efficiencies were obtained using cotton gloves for two hand conditions, dry or saliva moistened (wet). In addition, three contact scenarios were evaluated for both hand conditions: one, two, or three contacts with contaminated surfaces. Dermal transfer efficiencies were calculated for both hand conditions and used as inputs in a Stochastic Human Exposure and Dose Simulation model (SHEDS-Multimedia, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, N.C.). Results of this study showed that average dermal transfer efficiencies of methamphetamine ranged from 11% for dry hands to 26% for wet hands. There was a significantly higher wet transfer as compared to dry transfer for all surfaces. For wet hands, dermal transfer depended on surface type with higher transfer from carpet and linoleum as compared to drywall. Based on our estimates of dermal transfer efficiency, a surface contamination clearance level of 1.5 μg/100 cm² may not ensure absorbed doses remain below the level associated with adverse health effects in all cases. Additional dermal transfer studies should be performed using skin surrogates that may better predict actual skin transfer.     

A model for a comprehensive assessment of exposure and lifetime cancer incidence risk from plutonium released from the Rocky Flats Plant, 1953-1989.

A model was developed to calculate ambient air concentrations, surface deposition, and lifetime carcinogenic risk with uncertainty from plutonium released to the air from the Rocky Flats Plant between the years 1953 and 1989. The model integrated airborne release estimates and atmospheric dispersion and deposition calculations from 37 years of routine plant operations and episodic releases. Episodic releases included two major fires in 1957 and 1969 that breached the building air filtration systems, and suspension of plutonium contaminated soil from the former 903 waste storage area during high winds. Predicted air concentrations included contributions from site releases and resuspension from contaminated soil. Inhalation was the only exposure pathway considered. Environmental measurements suitable for model validation were lacking for the period when major site releases occurred (1953 to 1970). However, environmental media, such as soil and lake sediment, are natural accumulators and provided evidence of past offsite releases. The geometric mean predicted-to-observed (P/O) ratio for soil was 0.93 with a geometric standard deviation of 1.6. The model systematically underpredicted concentrations near the 903 Area because large, nonrespirable particles that deposited close to the source were not included in release estimates. Plutonium soil inventories for the model domain had P/O ratios ranging from 0.22 to 4.2. The geometric mean P/O ratio for ambient air was 0.90 with a geometric standard deviation of 2.6. Age-dated sediment cores from Standley Lake had a geometric mean P/O ratio of 1.0 with a geometric standard deviation of 1.7. Predicted-to-observed ratios for plutonium inventories in Great Western Reservoir ranged from 0.36 to 1.7. Lifetime cancer incidence risks were calculated for a male laborer scenario who resided in the model domain for the entire assessment time. Maximum cancer risks ranged from 10-6 (5th percentile) to 10(-4) (95th percentile). Most of the exposure was incurred during the 1950's.     

Air pollution by 3,4-benzo(a)pyrene in mines using self-propelled equipment with diesel motors

The study was designed to analyse air pollution by 3,4-benz(a)pyrene released together with exhaust gases in 3 underground mines where self-propelled machines with diesel engines are used. Concentration levels for 3,4-BP have been identified in air, dust, sweeping away and scraping off the walls of the mine working surface. It is demonstrated that in a great number of samples 3,4-BP concentration exceeds MAC. A technique for 3,4-BP air sampling and analysis has been studied by means of liquid chromatography with ultraviolet detection. Hygienic recommendations on decreasing 3,4-BP release into the mine air are set forth.     

The persistence of flood-borne pathogens on building surfaces under drying conditions

Previous research into microbial persistence on material surfaces following flooding has produced a wide range of results due to differing experimental conditions, including the temperature and humidity conditions of the experimental material and/or surrounding air. However, investigations to identify and quantify these factors and their links to the hygrothermal properties of building materials and the transient environmental conditions are rarely reported. This paper examines the viability of bacterial species on drying material surfaces that have been saturated with water or synthetic sewage. Escherichia coli and Enterococcus faecalis were inoculated on brick, wood, or plaster and allowed to dry at the conditions intended to mimic the remediation environments commonly found in domestic dwellings following a flood event. The inactivation rates were compared between environmental conditions, water type and the material properties of the surfaces. Significant differences were found in the declines in E. coli according to water type, the surface relative humidity and air relative humidity and between drying rates for sewage floods. Simulations using hygrothermal software were performed to illustrate the wide variation in material drying rates under different scenarios, taking into account material size, wall composition, and ventilation. The significantly differing rates of microbial death on flooded building materials under different drying regimes suggest that building simulation models can be useful tools for predicting the level and duration of microbial contamination in buildings following a flood event. A better understanding of microbial survival on drying surfaces can be used to assess the health risks to occupants in flood affected properties.     

Functional separation of septic and aseptic surgical procedures

Current evidence does not favour constructional over functional separation of septic and aseptic surgical procedures in terms of overall hygiene maintenance and incidence of skin and soft tissue infections. In both laminar and turbulent flow air operating theatres, air is not a relevant source of pathogens if surface disinfection is carried out properly.Final cleaning after a septic procedure includes a thorough wipe-disinfection of all potentially contaminated near and distant surfaces, including maintaining the necessary and effective exposure time of the chosen surface disinfectant. Cleaning utensils and clothes of all team members must be disposed of before leaving the theatre, and a complete change of gowns is mandatory before re-entering the operating room area. Strict adherence to this code of behaviour will allow for efficient functional separation of clean and contaminated surgical procedures without compromising patient safety.     

Release of simulated anthrax particles from disposable respirators

A preliminary study was undertaken to evaluate the potential for a disposable respirator that has been contaminated with anthrax spores to release spores in handling after use. The release of inert particles from disposable respirators was measured for masks dropped 3 feet onto a hard surface. Ten experimental runs were conducted for each of two N95 mask types, the Moldex 2200N95 and the 3M 8210. Anthrax spores were simulated with a test aerosol of single and double 1-micron polystyrene spheres. For the Moldex mask loaded with approximately 20 million spheres on it, an average of 0.16% was released; for the 3M mask an average of 0.29% was released.     

Quantification of nanoparticle release from polymer nanocomposite coatings due to environmental stressing

Certain engineered nanoparticles (ENP) reduce the flammability of components used in soft furnishings (mattresses and upholstered furniture). However, because of the ENP's small size and ability to interact with biological molecules, these fire retardant ENPs may pose a health and environmental risks, if they are released sometime during the life cycle of the soft furnishing. Quantifying the released amount of these ENPs under normal end-use circumstances provides a basis for assessing their potential health and environmental impact. In this article, we report on efforts to identify suitable methodologies for quantifying the release of carbon nanofibers, carbon nanotubes, and sodium montmorillonites from coatings applied to the surfaces of barrier fabric and polyurethane foam. The ENPs released in simulated chewing and mechanical stressing experiments were collected in aqueous solution and quantified using Ultraviolet-Visible and inductively coupled plasma–optical emission spectroscopy. The microstructures of the released ENPs were characterized using scanning electron microscopy. The reported methodology and results provide important milestones to estimate the impact and toxicity of the ENP release during the life cycle of the nanocomposites. To our knowledge, this is the first study of ENP release from the soft furnishing coating, something that can be important application area for fire safety.     

二氧化氯气体对空气和物体表面消毒效果的观察

目的:研究二氧化氯气体对空气和物体表面的消毒效果。方法:采用模拟现场试验和现场试验的方法。结果:空气中二氧化氯浓度为8 mg/m3,作用30 min,对气雾室中白色葡萄球菌的平均杀灭率99.96%;对空气中自然菌的平均杀灭率为99.61%。作用60 min和120 min,对物体表面模拟现场试验中金黄色葡萄球菌在载体为布片的平均杀灭率为96.19%和99.20%,在载体为玻璃片的平均杀灭率为55.25%和86.02%,对物体表面模拟现场试验中枯草杆菌黑色变种芽孢在载体为布片的平均杀灭率为75.57%和87.06%,在载体为玻璃片的平均杀灭率为47.56%和65.51%;对物体表面自然菌的平均杀灭率为75.05%和89.13%。结论:二氧化氯气体对空气具有良好的消毒效果,在相同浓度条件下对不同物体表面消毒有一定差异。