Indoor Atmosphere Research Articles

Passive Sampling and Monitoring of Radon and Other Gases

Passive sampling of radon gas may exploit different phenomena such as the adsorption, solubility, diffusion, and permeability of radon gas in different materials. Sampling methods are described for radon gas which, in principle, apply to all gases. For example, the combination of the polyethylene-based permeation membrane with activated charcoal has been successfully applied for the sampling and monitoring of radon gas and volatile organics often encountered in indoor atmospheres.

Radiation dose to the human respiratory tract from inhalation of radon-222 and its progeny

In this article the regional dose equivalent for exposure to 1 working level month (WLM), the annual effective dose equivalent and the dose equivalent conversion factor due to the inhalation of short-lived radon progeny ( 218Po, 214Pb and 214 Bi 214 Po ) are calculated with a dosimetric model. Experimental results of aerosol size characteristics, unattached activity fractions, equilibrium factors, and activity size distribution of the short-lived radon progeny in indoor and outdoor atmosphere are summarized. Dose calculations based on these results show that the changes in dose rate values are influenced by the different model assumptions concerning deposition probabilities of aerosol particles in the respiratory system during inhalation, the sensitivity of different cells (epithelial, basal) to radiation and assuming nose or mouth breathing. The inverse relationship between the unattached fraction of potential alpha-particle energy in room air and the radioactive equilibrium between radon gas and its progeny indicates that dose equivalent is closely related to the concentration of radon gas averaged over a period of exposure.

Methodology for Mixed Field Inhalation Dosimetry in Monazite Areas using a Twin-Cup Dosemeter with Three Track Detectors

A methodology is proposed for estimating the gas and potential alpha energy concentrations (PAECs), and inhalation dose rates due to a mixed field of radon, thoron and their progeny present in the indoor atmosphere, using a radon-thoron discriminating dosemeter having three solid state nuclear track detectors (SSNTDs). The gas concentrations present in the vicinity of the dosemeter are directly measured through SSNTDs exposed in the 'cup mode'. The bare track density rates are related to the gas and the progeny concentrations by incorporating ventilation rate dependent spatial profiles for thoron gas. The ventilation rate is extracted as a real positive root of the governing equation and from this, the PAECs as well as the inhalation dose rates are estimated through the use of standard formulae. Error estimates on the dose rates have been carried out. Analyses of the field data from a sample survey of 35 houses situated in monazite bearing high background radiation areas of Kerala indicate that the methodology works successfully in a majority of the cases. Results for 22 cases which showed less than 100% statistical error are presented. These show median values of about 4.8 Bq.m-3 and 462 Bq.m-3 for radon and room averaged thoron concentrations, 0.5 mWL and 129 mWL for radon progeny and thoron progeny PAECs, and 1.21 µSv.h-1 for inhalation dose rate. Although a complete picture would emerge only at the end of the ongoing large scale survey, the sample survey already indicates that indoor thoron levels in the Kerala monazite area are the highest reported so far in the literature.

Iso- and Anteiso-Alkanes: Specific Tracers of Environmental Tobacco Smoke in Indoor and Outdoor Particle-Size Distributed Urban Aerosols

Branched iso- and anteiso-alkanes were conjointly used, with n-alkanes and PAHs, as specific molecular markers to trace environmental tobacco smoke (ETS) in particle-sized aerosols collected in the indoor and outdoor urban atmosphere. GC/MS and GC-FID were used for the de termination of iso-, anteiso-, and n-alkanes and PAHs. The branched alkanes (ranging from C29 to C33) were detected only in particles in the accumulation range mode (<1.5 μm) in both indoor and outdoor samples. The concentrations of iso- and anteiso-alkanes in the indoor aerosols (0.75−8.53 ng/m3) were higher than those measured in outdoor samples (0.77−1.51 ng/m3). The indoor aerosol pattern of iso-, anteiso-, and their calculated diagnostic concentration ratios were characteristic for ETS. The compound distribution pattern of indoor n-alkanes (ranging from C21 to C33) was of biogenic origin, and the use of odd-to-even predominance running ratio curves indicated their cigarette smoke origin. The corresponding outdoor pattern and concent...

Characterisation of corrosivity in indoor atmospheres with different metals and evaluation techniques

Abstract Owing to corrosion effects of, for example, electronics or objects representing our cultural heritage, there is an obvious need to predict the corrosivity in any given indoor environment. A standard method adopted by the Instrument Society of America is based on the exposure of copper coupons typically over a 1-3 month period and prediction of corrosivity on the basis of measurements of corrosion product thickness by cathodic reduction. The main aim of the present work has been to obtain more reliable predictions than is currently possible through the exposure of several reference metals rather than copper alone, and by exploring other methods of corrosion effect evaluation than cathodic reduction. The results show that both mass loss and mass increase measurements are alternative techniques to cathodic reduction. More reliable corrosivity predictions can be made with longer exposure times and with more reference metals. The exposure of copper as the reference metal can provide information on the...

Characterisation of corrosivity in indoor atmospheres with different metals and evaluation techniques

Characterisation of corrosivity in indoor atmospheres with different metals and evaluation techniques

工業化住宅内各部位の環境腐食性

工業化住宅内各部位の環境腐食性

Dosimetry, toxicity and carcinogenicity of inspired acetaldehyde in the rat

Acetaldehyde is a ubiquitous air pollutant. It is an important industrial chemical and is also produced during the combustion of wood or tobacco. In smoky indoor atmospheres concentrations of the aldehyde may reach 100 ppb. Acetaldehyde is metabolized to acetate (releasing hydrogen ion) by aldehyde dehydrogenase a process which, in most tissues, represents a detoxification pathway. In vitro, acetaldehyde forms DNA–DNA and DNA–protein crosslinks. It is a clastogen, and inducer of sister chromatid exchanges, and is, perhaps, a weak mutagen. Inhalation exposure to 1000 ppm may induce DNA–protein crosslink formation in nasal tissues in the rat in vivo. Inhalation toxicity studies have shown acetaldehyde vapor causes chronic tissue injury and tumor formation in nasal tissues at exposure concentrations of 750 ppm or higher, with nasal olfactory mucosa being more sensitive than respiratory mucosa. Dosimetric estimates suggest that marked tissue injury and carcinogenicity occurs only at inspired concentrations which are sufficiently high to overwhelm nasal aldehyde dehydrogenase detoxification capacity. The induction of squamous cell carcinomas in the respiratory mucosa by acetaldehyde displays many analogies to the induction of squamous cell carcinomas by formaldehyde. For both vapors, non-linear concentration response relationships are observed for DNA–protein crosslink formation, tissue injury, and carcinogenicity, suggesting these responses are associated. For both vapors it is possible to document an exposure concentration that produces nasal respiratory epithelial injury without increasing tumor incidence, suggesting that for respiratory mucosa-derived tumors, exposure to non-cytotoxic concentrations may pose limited carcinogenic risk. In addition to squamous cell carcinomas of the respiratory epithelium, acetaldehyde exposure also results in nasal olfactory injury and tumors (adenocarcinomas) in the rat. The studies performed to date have not demonstrated a no observable effect level for these responses, therefore, the precise role of cytotoxicity and regenerative cell proliferation in the carcinogenic process in olfactory tissues can not be evaluated. Acetaldehyde metabolism via aldehyde dehydrogenase results in the formation of two hydrogen ions. The olfactory mucosa is quite sensitive to acid and dosimetric estimates suggest that the intracellular acid production rates that may occur in olfactory mucosa during acetaldehyde exposure may be sufficiently high to cause tissue damage. Such acid-induced tissue damage may enhance the genotoxic and tumorigenic potential of acetaldehyde in olfactory mucosa, and may, therefore, represent an important process in the production of tumors in this tissue.

Allergic potential of someAspergilli on saw mill workers in Lucknow, India

Fifty fungal types were isolated from the indoor atmosphere of saw mills by exposing Petri plates containing Czapek-dox Agar, Potato-dextrose Agar and Sabouraud Agar media for 5 min. The fungal flora of the outdoor surroundings was also studied for comparison. Species ofAspergilli dominated in the saw mills, being represented by 16 species including one ascosporic form. Other fungi were species ofCladosporium, Alternaria, Curvularia, Penicillium, Fusarium, etc. Variations in the fungal population in different months were also observed. Fungal spores recovered using the Rotorod Sampler wereAlternaria, Curvalaria lunata, Curvularia tetramera, Cladosporium, Dreschslera sp.,Epicoccum sp.,Pithomyes sp.,Nigrospora, Stemphylium sp. andTorula sp. Mycelial fragments and unidentifiable spores were also seen in abundance. Varying allergic responses of patients were also recorded by testing intradermally, the antigens of nineAspergilli, vizAspergillus flavus, A. fumigatus, A. japonicus, A. melleus, A. nidulans, A. niger, A. niveus, A. tammarii and A. terreus.

Fungal population in the atmosphere of Ismailia City

Fungal spore populations in the outdoor and indoor atmosphere of Ismailia have been studied during the period from March 1992 to May 1993. A total of 23 350 cfu and 73 species were recorded,Cladosporium cladosporioides, Aureobasidium pullulans andAspergillus flavus were the most abundant. The indoor and outdoor mycoflora showed marked quantitative and qualitative differences. In view of count, recorded species could be categorized into three groups as follows: (a) species showing higher counts in out- than indoor, (b) species showing the opposite trend i.e. lower counts in out-door than indoor, (c) species showing approximately equal counts in out- and indoor. Regarding seasonal periodicity, March and either September or October showed the highest count for both normal fungal flora (NFF) and opportunistic fungal flora (OFF). While January and July showed the lowest count of them both, May but not July was the lowest as for outdoor NFF.

Immunological findings in groups of children after compensatory measures

In 200 children residing permanently in a region with a high level of atmospheric pollution, indicators of humoral immunity, salivary immunity and specific IgE antibodies were determined before and after 14 days' attendance at an “outdoor school” in rural areas with a very low level of atmospheric pollution. A marked reduction of elevated albumine levels, which are characteristic of irritation or even inflammation in the oral cavity or respiratory tract, was found, as well as increasing levels of SIg A and lysozyme in saliva. The two-week stay in the outdoor school resulted in decreased IgE specific antibodies of the respiratory type of allergy (CAP Phadiatop). In the group of atopic children there were found high total IgE levels, with a trend of depression after 2 weeks in the outdoor school. Higher values of some immunoglobulins were observed, while low levels of IgA were found in some children with high frequency of respiratory diseases. The irritant effect of polluted atmosphere and the quality of indoor atmosphere influence some immunological parameters in children.

The initial atmospheric behavior of radon decay products

The chemical and physical properties of218Po immediately following its formation from222Rn decay are important in determining its behavior in indoor atmospheres and play a major part in determining its potential health effects. In 88% of the decays, a singly charged, positive ion of218Po is obtained at the end of its recoil path. These ions can interact with water vapor or other volatile organic compounds (VOCs) that may exist in indoor air. The ions can be neutralized by 3 different mechanisms, small-ion recombination, electron transfer, and electron scavenging. In typical indoor air, the ion will be rapidly neutralized by transfer of electrons from lower ionization potential gases such as NO2. The neutral molecule can then become incorporated in ultrafine particles formed by the radiolytic processes in the recoil path. These particles will typically be formed by the presence of the air ions produced by the passage of the emitted α-particle through ion-induced nucleation. In addition these energetic ions can react with water molecules to produce hydroxyl radicals. Thus, the decay of the radon nucleus produces a variety of effects and can result in changes in the size of the radioactive species that includes the radon progeny.

Hygroscopicity of indoor aerosols and its influence on the deposition of inhaled radon decay products

Consumer spray products, combustion products, and cooking aerosols are the significant sources of airborne particles to the indoor atmosphere. These particles serve as carriers of radon decay products to the lungs. When inhaled, some particles will extract water from the air at the high relative humidity (RH ∼99.5%) in the respiratory tract and grow in size. Since the deposition of particles in different compartments of the lungs, and hence the inhaled dose, depends on the size of the particles, it will be different for the particles that grow from those that do not. The study of the hygroscopic growth of these indoor aerosol particles was performed using a tandem differential mobility analyzer. Dry monodisperse particles of known initial size were selected by the first differential mobility analyzer (DMA) and then exposed to high RH (99-99.5%) in a growth chamber using a wetted water reactor. The size of these particles was measured by the second DMA. It was observed that some products do not grow at all, whereas others exhibit moderate to high growth. A comparative study of the deposition of the inhaled growing and non-growing particles, and its influence on the lung dosimetry, is presented.

Monitoring Indoor Ambient Atmospheres for Volatile Organic Compounds Using an Ion Mobility Analyzer Array with Selective Chemical Ionization

Abstract Three ion mobility analyzers with different reagent gases for chemical ionization were interfaced to a single computer and operated with a software package created for simultaneous and continuous monitoring of 1 to 8 analyzers. Mobility spectra were collected and digitized on separate input channels with 200 ms sampling intervals for individual analyzers. Volatile organic compounds (VOCs) in indoor ambient atmospheres were monitored in two scenarios: laboratory air during designed releases of several VOCs and ambient air in a central chemistry storeroom used for undergraduate laboratories. The ion mobility analyzer with reagent ions of H(H2O)+ n (n = 2 – 4) exhibited response toward alcohols, aldehydes, and other VOCs with low proton affinities. However, analyzers with reagent ions of elevated proton affinity including acetone and dimethylsulfoxide showed selective response toward only VOCs with proton affinities greater than that of the reagent ion. Thus, two tiers in selectivity of array respon...

Corrosion of metallic materials

Corrosion processes are important in the degradation of electronic components. By nature of thin and closely-spaced metallic sections, electronic components are prone to corrosion failures even in the presence of traces of moisture and contaminants. Atmospheric corrosion, an electrochemical process under the influence of thin-film electrolytes, is primarily responsible for corrosion damage in electronics and can lead to premature failures even in indoor atmospheres. In attempting to minimize the risk of corrosion failures, it is important to account for corrosion damage during the design stage, manufacturing processes, storage, shipping, and in service use. Carefully-designed accelerated corrosion-tests are used to predict the performance of electronic components. Many sensitive analytical techniques and instrumentation are available for determining the mechanism and causes of electronic corrosion failures. Many sources of corrosion information are available for consultation on the performance of candidate materials, but, unfortunately, most are not tailored specifically to the electronics industry.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Appropriate Sampling Strategies for the Measurement of Formaldehyde in Indoor Air

Active and passive sampling methods are available for the determination of maximum formaldehyde concentrations and average formaldehyde concentrations respectively. The present work compares the performance of an active cartridge type sampler with an impinger method and a diffusive monitor which have previously been used at the Building Research Establishment. Good agreement between the three methods was found in a comparison at two formaldehyde concentration levels. The sampling strategy required to obtain a representative reading of the formaldehyde concentration in an indoor atmosphere was investigated using a commercially available diffusive sampler. An investigation of spatial variation in five rooms suggests that sampling in one location should give a representative reading of the formaldehyde concentration in a room, providing the sampler is not placed near a major source of formaldehyde. An initial investigation of temporal variation in six rooms found that one three day sampling period was sufficient to obtain a representative reading of the mean monthly formaldehyde concentration. Between month variation was found to be higher than within month variation although no strong seasonal effects were observed. The results suggest that more than one three day sampling period should be used to estimate the annual mean formaldehyde concentration and two measurements (summer and winter) may be a reasonable approach. Further work in a larger number of homes is in hand to verify the effectiveness of this sampling strategy.

Effects of exposure to environmental tobacco smoke on a human tracheobronchial epithelial cell line

BEAS-2B cells, a human bronchial epithelial line immortalized by viral transformation, were exposed to sidestream tobacco smoke (STS) as a surrogate for environmental tobacco smoke (ETS) under biphasic culture conditions where the apical portion of the cells was in direct contact with the gas phase. Dose-dependent cytotoxicity was observed. In addition, induction of an as yet uncharacterized protein of molecular weight 45 000 was associated with exposure to STS. This protein might be part of a protective response of exposed cells, which do not show a classical heat shock response when exposed to STS. We conclude that STS and ETS can be directly cytotoxic to human airway epithelial cells in biphasic culture at concentrations not unreasonable for smoky indoor atmospheres. The model system described in this paper should be useful for studying the detailed mechanisms of cytotoxicity of, and protection from, ETS exposure in the human cells most directly exposed to ETS in vivo.

Passive track detectors for radon determination in the indoor environment

Solid-state nuclear track detectors are increasingly being used for the measurement of time-integrated radon levels in dwellings under different conditions. This paper presents the results of Rn measurements in the indoor atmosphere of Manzini Town and the University of Swaziland campus using CR-39 plastic track detectors. The results show that radon concentrations in the indoor atmosphere vary with the ventilation conditions. The books present in a library can also serve as Rn emitters and thus may increase health risks. The equilibrium factor ( F) and the effective dose equivalent ( Hg) were determined. The recorded values lie below the international guidelines.

Modular sampling and inlet systems for mobile environmental mass spectrometry

Sampling systems and gas Chromatographic separators based on a modular concept have been developed for a mobile/portable quadrupole mass spectrometer. A special quick connector, designed to easily mount and remove the gas Chromatograph from the mass spectrometer, allows the operator to switch between different GC modules within minutes. A polysiloxane inlet membrane seals the vacuum chamber and prevents it from being vented, even during the exchange of GC modules. Since the GC's injector modules are designed as separate units, diverse injector systems can also be removed and swapped using similar quick interfaces, while the GC module remains connected to the mass spectrometer. Fast GC runs with short-capillary GC modules accelerate measurements dramatically. Using a spray extractor, volatile organic compounds in water can be sampled and trapped in the sorbent tube of the automatic air sampler for GC-MS analysis. A quick analysis can be made using the transfer-line GC with the sniffer probe. Examples are given of applications involving the analysis of polycyclic aromatics and other contaminants in soil samples, and analytical results on volatile organic compounds in air, in indoor atmospheres and in water. The concept of this modular system makes the whole instrumentation flexible, and permits a wide variety of mass spectrometry applications by using the right combination of sampling modules.

Evaluation of Room Air Cleaners for the Reduction of Exposure and Dose to Indoor Radon Progeny

Abstract Since the proximate source of dose to the cells of the bronchial epithelium is the deposited radon progeny, the exposure and resulting dose could be reduced if the radon decay products were effectively removed from the indoor atmosphere. Thus, room air cleaners could be effective in reducing the risks associated with indoor radon. However, because of the short half-life of 218Po, it grows back quickly and in the altered aerosol conditions that are produced by the presence of an air cleaner, the exposure/dose conditions as well as the magnitude of the dose can be substantially changed. To examine the nature of the exposure of individuals in normally occupied homes and to determine the effect of various types of room air cleaners on the exposure to and dose from the indoor radon progeny, a series of measurements have been made using an automated graded screen array system. Two extended experiments were performed in homes in Amprior, Ontario, and Parishville, NY, in which filtration systems, a positive ion electrostatic precipitator, and ioniser/fan systems have been tested for their ability to remove both airborne radioactivity and particles. In both experiments, measurements were made over one week periods with an air cleaner operating the distributions of exposure are compared with measurements of the background conditions when no cleaner is functioning. The dose to both basal and secretory cells of the bronchial epithelium in the first eight generations of the bronchus were calculated using the model developed by James and their distributions are compared among the various exposure conditions. In most cases the presence of the air cleaner reduced the exposure to radon progeny. However, the reductions in dose were generally substantially smaller than the reductions in exposure. In the intercomparisons of the two filtration units and the two identical ioniser/fan systems, the units generally behaved in a similar manner. The results of this substantial set of measurements are summarised and the needs for further studies in this area described.