Indoor Atmosphere Research Articles

1120 雰囲気モニタリングによる火災危険予測システムの開発(J05-2 ライフサポート(2)(計測・監視),J05 ライフサポート)

Every year, more than 50,000 fires break out in Japan. Most of deceased person by fire are elderly people over 65 year old. Thus, the fire risk detection system has been needed to protect for their lives. This paper proposes the system that evaluates a degree of fire risk by watching the usage of stoves, cooking-heaters, electric appliances or monitoring atmosphere in a living-room directly and so on. As a first step of this study, we carried out laboratory experiments to monitor indoor atmosphere such as CO, H_2, and Smell using gas sensors. After the feature data is extracted from sensor output signal by the method which we proposed, the Mahalanobis' distance is evaluated for distinguishing either safety or dangerous situation.

An extensive indoor 222Rn/220Rn monitoring in Shillong, India

The behaviour of ubiquitous radon (222Rn), thoron (220Rn) and their progeny in the indoor atmosphere generally reflects a complex interplay between a number of processes, the most important of which are radioactive alpha-decay, ventilation, attachment to aerosols and deposition on surfaces. The present work involved a long-term (1997-2000) passive monitoring of 222Rn and 220Rn in the indoor environment of Shillong, Meghalaya. The north-east region of India being a zone of high seismicity, the indoor radon and thoron map of the region will provide a better insight and a valuable database for any study related to radon and thoron anomalies.

Indoor environment and conservation in the Royal Museum of Fine Arts, Antwerp, Belgium

Indoor and outdoor atmospheres of the ‘Koninklijk Museum voor Schone Kunsten’ (KMSK, Royal Museum of Fine Arts) in Antwerp, Belgium, were thoroughly characterised to determine the air quality inside the museum and the factors controlling it. During a winter and a summer campaign aerosol particles, pollutant gases, bacteria and fungi were sampled and different indoors microclimatic parameters were measured. The chemical composition of particulates suspended in indoor and outdoor air was analysed, both with reference to bulk aerosol matter and to individual particles. Outdoor sources largely determined the composition of indoor aerosol. The main particle types identified in winter were Ca-rich, Ca–Si and sea salt particles. In summer, S-rich particles were most abundant. Dry deposition was sampled in order to determine the amount of particulate matter that could potentially deposit onto the works of art. The concentrations of NO 2 and SO 2 amounted to 12 and 5–6 ppb, respectively, both in winter and in the summer. The microclimates inside the exhibition rooms were affected by poorly balanced heating and air-conditioning, free-standing humidifiers, ventilating and lighting systems and the daily flux of visitors, which produced rapid changes and marked thermo-hygrometric gradients. Based on these results, suggestions for the improvement of the heating and air-conditioning system could be made. Microbial loads were higher in summer than in winter. However, the proportion of microorganisms capable of degrading proteins or hydrolysing fats, and thus pernicious to works of art, was not significantly increased inside the museum.

Indoor environment and conservation in the Royal Museum of Fine Arts, Antwerp, Belgium

Indoor and outdoor atmospheres of the ‘Koninklijk Museum voor Schone Kunsten’ (KMSK, Royal Museum of Fine Arts) in Antwerp, Belgium, were thoroughly characterised to determine the air quality inside the museum and the factors controlling it. During a winter and a summer campaign aerosol particles, pollutant gases, bacteria and fungi were sampled and different indoors microclimatic parameters were measured. The chemical composition of particulates suspended in indoor and outdoor air was analysed, both with reference to bulk aerosol matter and to individual particles. Outdoor sources largely determined the composition of indoor aerosol. The main particle types identified in winter were Ca-rich, Ca–Si and sea salt particles. In summer, S-rich particles were most abundant. Dry deposition was sampled in order to determine the amount of particulate matter that could potentially deposit onto the works of art. The concentrations of NO 2 and SO 2 amounted to 12 and 5–6 ppb, respectively, both in winter and in the summer. The microclimates inside the exhibition rooms were affected by poorly balanced heating and air-conditioning, free-standing humidifiers, ventilating and lighting systems and the daily flux of visitors, which produced rapid changes and marked thermo-hygrometric gradients. Based on these results, suggestions for the improvement of the heating and air-conditioning system could be made. Microbial loads were higher in summer than in winter. However, the proportion of microorganisms capable of degrading proteins or hydrolysing fats, and thus pernicious to works of art, was not significantly increased inside the museum.

Measurement of Equilibrium Factor ”F” between Radon and its Progeny and Thoron and its Progeny in the Indoor Atmosphere Using Nuclear Track Detectors

Radon, thoron and their progeny are present in the indoor atmosphere as attached and unattached fractions. The level of ventilation in a house and the plating out of radon/thoron daughters onto surfaces decide the extent of equilibrium between them. Since the daughter products are mainly responsible for the inhaled dose, the measurement of the equilibrium factor, F, between radon/thoron and their progenies is desirable. It is therefore necessary to measure the equilibrium factor for different types of house construction, locations and seasons before projecting the dose from the measurements of radon and thoron. This paper presents the results of the measurement of F between radon, thoron and their progenies in dwellings using the LR-115 type II plastic track detector. The exposures were made with a twin-chamber dosimeter in about 150 houses of different types, distributed at different locations in the Garhwal and Kumaun region of the Himalayas in India. The measured equilibrium factor between radon and progeny varied from 0.02 to 0.90 with an average value of 0.28 while the same factor for thoron and progeny was found to vary from 0.01 to 0.90 with an average value of 0.09. The methods of measurement and results obtained are discussed in detail.

Measurement of Radon and Thoron Concentrations in the Indoor Atmosphere and Drinking Water of Eastern Doon Valley, India

Radon and radium content were measured in water samples from tubewells and handpumps in the eastern Doon valley, India. Activity due to the radon concentration was found to vary from 25.4 to 72.3 Bq L-1, whereas activity due to radium in selected water samples varied from 0.10 to 0.84 Bq L-1. The values recorded for radon were generally higher than those reported by various other workers for drinking water but well below the maximum levels that have been recorded. Measurements of indoor radon, thoron and their daughter products were also made in the houses in the same area for all the four seasons of a year on a time integrated cycle using twin chamber dosimeters. Concentrations of indoor radon and thoron varied from 28.4 to 63.7 Bq m-3 and 0.01 to 15.9 Bqm-3, respectively. The total resultant radiation dose to occupants in the houses surveyed in the eastern Doon valley varied from 0.03 to 0.11 μSv h-1. A detailed analysis of the radon and thoron distribution in different houses with seasonal variation and ventilation conditions and a description of the geology of the area is presented in this paper.

亜鉛の大気・室内腐食における速度式W=at<sup>n</sup>

亜鉛の大気・室内腐食における速度式W=at<sup>n</sup>

Proposição de um reator fotocatalítico para destruição de microrganismos em ambientes interiores

The TiO2/UV photocatalytic reactor was investigated as an alternative system to inactivate airborne microorganisms. The experiments performed in the absence of the catalyst showed that direct photolysis was not efficient to destruct microorganisms, with only 30% of inactivation. Similar inactivation percentage was obtained using TiO2 in absence of UV radiation. The destruction of microorganisms present in a contaminated indoor atmosphere, using the combination of TiO2/UV was very efficient, reaching more than 98% of destruction.

Monitoring and modelling of indoor radon concentrations in a multi-storey building at Mumbai, India

Radon (Rn 222) levels in an indoor atmosphere of a multi-storey building at Mumbai have been measured for one year covering all the four seasons. Monitoring was carried out using the time-integrated passive detector technique, using Kodak-115 type Solid State Nuclear Track Detector (SSNTD) films of 2.5×2.5 cm size. Measured indoor radon levels showed a decreasing trend with height with concentration ranging from 41 Bq m -3 at ground floor level to 15 Bq m -3 at 19th floor level. Using the UNSCEAR (1993) dose conversion factors, the inhalation dose due to breathing of radon gas is estimated to be 1.03 mSv y -1 at the ground floor to 0.38 mSv y −1 at the 19th floor level. Measured indoor radon concentrations on each floor were compared with the computed values using a mathematical model. The agreement between measured values and calculated values of indoor concentrations at different floors was very good within the limitations of various field parameter values.

The heterogeneous hydrolysis of NO2 in laboratory systems and in outdoor and indoor atmospheres: An integrated mechanism

The heterogeneous reaction of NO2 with water on the surface of laboratory systems has been known for decades to generate HONO, a major source of OH that drives the formation of ozone and other air pollutants in urban areas and possibly in snowpacks. Previous studies have shown that the reaction is first order in NO2 and in water vapor, and the formation of a complex between NO2 and water at the air–water interface has been hypothesized as being the key step in the mechanism. We report data from long path FTIR studies in borosilicate glass reaction chambers of the loss of gaseous NO2 and the formation of the products HONO, NO and N2O. Further FTIR studies were carried out to measure species generated on the surface during the reaction, including HNO3, N2O4 and NO2+. We propose a new reaction mechanism in which we hypothesize that the symmetric form of the NO2 dimer, N2O4, is taken up on the surface and isomerizes to the asymmetric form, ONONO2. The latter autoionizes to NO+NO3−, and it is this intermediate that reacts with water to generate HONO and surface-adsorbed HNO3. Nitric oxide is then generated by secondary reactions of HONO on the highly acidic surface. This new mechanism is discussed in the context of our experimental data and those of previous studies, as well as the chemistry of such intermediates as NO+ and NO2+ that is known to occur in solution. Implications for the formation of HONO both outdoors and indoors in real and simulated polluted atmospheres, as well as on airborne particles and in snowpacks, are discussed. A key aspect of this chemistry is that in the atmospheric boundary layer where human exposure occurs and many measurements of HONO and related atmospheric constituents such as ozone are made, a major substrate for this heterogeneous chemistry is the surface of buildings, roads, soils, vegetation and other materials. This area of reactions in thin films on surfaces (SURFACE = Surfaces, Urban and Remote: Films As a Chemical Environment) has received relatively little attention compared to reactions in the gas and liquid phases, but in fact may be quite important in the chemistry of the boundary layer in urban areas.

Characteristics of polycyclic aromatic hydrocarbons and total suspended particulate in indoor and outdoor atmosphere of a Taiwanese temple

Incense burning, a common and popular practice among many families and in most temples in Taiwan, can result in indoor pollution-related health problems. This exploratory study was aimed at characterizing human exposure to polycyclic aromatic hydrocarbons (PAHs) and total suspended particulate (TSP) inside and around a Taiwanese temple, and to compare the indoor levels with levels outside. Additionally, three types of commonly used unburned incense and incense ash were analyzed in order to evaluate the relationship between incense composition and PAH emissions. Standard methods were used to determine air concentrations of 21 PAHs and TSP inside and around a chosen temple. Indoor mean total-PAH concentration, particle-bound PAH concentration and TSP concentration were 6258 ng/m 3, 490 μg/g and 1316 μg/m 3, respectively; values for outdoor readings were 231 ng/m 3, 245 μg/g and 73 μg/m 3, for outdoors, respectively indicating PAH and TSP concentrations inside 27 and 18 times greater, respectively than outdoors. With respect to concentrations of individual PAHs (particulate+gas phase), the five highest concentrations were of acenaphthylene (AcPy) (3583 ng/m 3), naphthalene (Nap) (1264 ng/m 3), acenaphthene (Acp) (349 ng/m 3), fluoranthene (FL) (243 ng/m 3) and phenanthrene (PA) (181 ng/m 3). Median values for indoor/outdoor (I/O) ratios of individual PAHs ranged from 5.7 to 387.9, which implied that the temple was a significant PAH source. Moreover, PAH content of the tested stick incense and ash was very low. PAH levels inside the temple were much higher than those measured in the vicinity and inside residential houses; and were in fact close to levels measured at a local traffic intersection in Tainan, Taiwan, and those in a graphite-electrode producing plant during the graphitization process. It is obvious that such substantially high concentrations of PAHs and TSP constitute a potential health hazard to people working in or visiting the temple.

The internal consistency of the ‘analyst’ diffusive sampler—A long-term field test

A recently developed diffusive sampler, intended for use in long-term ambient measurements of volatile aromatic hydrocarbons, has been tested to determine the upper limits of its sampling capacity. A test has been performed over 12-month period to evaluate these limits in terms of its ‘internal consistency’ (i.e. checking if the sum of the amounts of a given pollutant, determined over shorter consecutive periods, matches the amount determined from a single long-term exposure). Results demonstrate that the uptake rate of the device, in a real (indoor) atmosphere, is constant for approximately 8 months for benzene and for approximately 10 months for toluene. The upper limit for higher homologous species was not reached after exposure for a year to typical ambient concentrations. This means the device can be successfully used for several months, thereby enabling low-cost determinations of ambient BTX concentrations.

Implication of Particle Sources in the Calculation of the Dose Arising from Exposure to Radon Progeny in Indoor Atmospheres

Radon is ubiquitous in the biosphere and present in soils and building materials. It accounts for about half of our total irradiation dose from natural sources. An association has been demonstrated in uranium miners between their exposure to radon and its decay products and an excess risk of lung cancer, however, any effect of domestic radon exposure in the production of lung cancer remains unclear. Epidemiologic and dosimetric approaches have been used to study the problem, but there is considerable variation between the results from each method. To better estimate the risk a European large-scale research programme has been conducted. One aim of the study was to better characterise the size distribution of particulates carrying radon progeny including their variation with time and ambient conditions. A methodology was developed to measure the particulate size distribution, unattached fraction and the equilibrium factor of ²²²Rn short-lived daughters. Measurements were made in a traditional dwelling built on a granitic soil in Brittany. Over 11 months, radon activity concentration was on average 1,420 Bq·m^–3 (240–2,800 Bq·m^–3), but it was concluded that such an approach only allows assessment of the dose as the sum of the unattached and attached forms.

Implication of Particle Sources in the Calculation of the Dose Arising from Exposure to Radon Progeny in Indoor Atmospheres

Radon is ubiquitous in the biosphere and present in soils and building materials. It accounts for about half of our total irradiation dose from natural sources. An association has been demonstrated in uranium miners between their exposure to radon and its decay products and an excess risk of lung cancer, however, any effect of domestic radon exposure in the production of lung cancer remains unclear. Epidemiologic and dosimetric approaches have been used to study the problem, but there is considerable variation between the results from each method. To better estimate the risk a European large-scale research programme has been conducted. One aim of the study was to better characterise the size distribution of particulates carrying radon progeny including their variation with time and ambient conditions. A methodology was developed to measure the particulate size distribution, unattached fraction and the equilibrium factor of 222Rn short-lived daughters. Measurements were made in a traditional dwelling built on a granitic soil in Brittany. Over 11 months, radon activity concentration was on average 1,420 Bq·m–3 (240–2,800 Bq·m–3), but it was concluded that such an approach only allows assessment of the dose as the sum of the unattached and attached forms.

Colorimetric determination of formaldehyde in air using a hanging drop of chromotropic acid

A simple and sensitive method to determine parts per billion (ppb) of atmospheric formaldehyde in situ, using chromotropic acid, is described. A colorimetric sensor, coupled to a droplet of 15.5 microL chromotropic acid, was constructed and used to sample and quantify formaldehyde. The sensor was set up with two optical fibers, a light emitting diode (LED) and two photodiodes. The reference and transmitted light were measured by a photodetection arrangement that converts the signals into units of absorbance. Air was sampled around the chromotropic acid droplet. A purple product was formed and measured after the sampling terminated (typically 7 min). The response is proportional to the sampling period, analyte concentration and sample flow rate. The detection limit is approximately 2 ppb and can be improved by using longer sampling times and/or a sampling flow rate higher than that used in this work, 200 mL min-1. The present technique affords a simple, inexpensive near real-time measurement with very little reagent consumption. The method is selective and highly sensitive. This sensor could be used either for outdoor or indoor atmospheres.

Molecular tracers for smoke from charring/burning of chitin biopolymer

Monosaccharide derivatives from the breakdown of cellulose are the major organic components of smoke particles emitted to the atmosphere from biomass burning. In urban areas a related biopolymer, chitin, may contribute markers to smoke from grilling/charring of crustacean seafood. 1,6-Anhydro-2-acetamido-2-deoxyglucose and the related degradation products from chitin can be utilized as specific and general indicator compounds for the presence of emissions from charring/burning of crustaceans in samples of atmospheric fine particulate matter. This enables the potential assessment of such cooking emissions in urban and rural areas. There are other compounds (e.g., thermal alteration derivatives from proteins and nucleic acids) which are additional key indicators in smoke from charring/burning of chitin. 1,6-Anhydro-2-acetamido-2-deoxyglucose is proposed as a specific indicator for chitin in biomass burning emissions. It is emitted at similarly high concentrations and emission rates as levoglucosan from cellulose burning that it should be detectable in certain indoor and urban atmospheres.

Ozone exposure inside museums in the historic central district of Krakow, Poland

Ozone present in the indoor atmosphere of museums can lead to the fading of organic artists’ pigments and textile dyes that are present in paintings, tapestries and historically important clothing exhibits. Ozone concentrations were measured in outdoor air and within the interior galleries of five institutions that house cultural properties in Krakow. The purpose of these experiments was to determine the degree of penetration of outdoor ozone into these museums, and in the case of the National Museum to determine the effectiveness of the existing ozone removal system at that site. It was found that those museums that are rapidly ventilated through many open doors and windows experienced indoor ozone concentrations about 42–44% as high as those outdoors. The Senator's Hall at Wawel Castle, which houses important tapestries, experiences indoor ozone concentrations that are 17–19% of those outdoors due to ozone removal at interior surfaces during transit through the building from distant air intake points. Methods for further reduction of ozone concentrations in the specific museums studied are discussed.

Corrosion measurements of silver and copper in indoor atmospheres using different evaluation techniques

The need to classify environments with respect to their corrosivity is important for a rational choice of preventive measures. One way to characterise a given indoor environment is to determine the corrosivity by measuring the corrosion attack on coupons of metals exposed to the atmosphere. The aim of the present study was to evaluate the agreement between different measuring techniques for the quantitative evaluation of corrosion effects of silver and copper in indoor conditions in order to find reliable corrosion measuring methods for low corrosivity environments. Measurements based on mass increase, mass loss, electrolytic cathodic reduction, and resistance sensors have been evaluated. The results show that mass increase measurements of copper and measurements with copper sensors give a good correlation with mass loss measurements. Cathodic reduction measurements for copper underestimate the corrosion effect. Mass increase and resistance sensor measurements of silver both seem to overestimate the corrosion effect. The formation of uneven corrosion films and the presence of soluble corrosion products make electrolytic cathodic reduction inaccurate for corrosion measurements of silver. For a better understanding of the accuracy of the investi gated techniques for silver corrosion measurements, procedures for mass loss determination need to be developed.

Corrosion measurements of silver and copper in indoor atmospheres using different evaluation techniques

Corrosion measurements of silver and copper in indoor atmospheres using different evaluation techniques

An annular diffusion channel equipped with a track detector film for long-term measurements of activity concentration and size distribution of nanometer 218Po particles

A new method is presented to estimate mean activity concentration and mean size distribution of nanometer 218Po over long time, i.e. several weeks in indoor atmospheres. It uses an annular channel, equipped with an LR 115 solid-state alpha-track detector, as diffusion sampler. Design, experimental characterisation and analytical methods are described. The calibration was carried out in a 0.35 m 3 test radon chamber without aerosol particles by comparing the number of tracks registered on the film detector with the nanometer 218Po particle concentrations measured in parallel with a classical single screen-filter method. A calibration factor of 0.107 tracks cm -2 h -1 was established. The size distribution of these nanometer radioactive particles in the range of 0.5–5 nm was reconstructed from the track density recorded on the detector film with non-linear inversion techniques.