Indoor Atmosphere Research Articles

Spatial and indoor/outdoor gradients in urban concentrations of ultrafine particles and PM2.5 mass and chemical components

In order to investigate relationships between outdoor air pollution and concentrations indoors, a novel design of experiment has been conducted at two sites, one heavily trafficked and the other residential. The novel design aspect involves the introduction of air directly to the centre of an unoccupied room by use of a fan and duct giving a controlled air exchange rate and allowing an evaluation of particle losses purely due to uptake on indoor surfaces without the losses during penetration of the building envelope which affect most measurement programmes. The rooms were unoccupied and free of indoor sources, and consequently reductions in particle concentration were due to deposition processes within the room alone. Measurements were made of indoor and outdoor concentrations of PM2.5, major chemical components and particle number size distributions. Despite the absence of penetration losses, indoor to outdoor ratios were very similar to those in other studies showing that deposition to indoor surfaces is likely to be the major loss process for indoor air. The results demonstrated a dramatic loss of nitrate in the indoor atmosphere as well as a selective loss of particles in the size range below 50 nm, in comparison to coarser particles. Depletion of indoor particles was greater during a period of cold weather with higher outdoor concentrations probably due to an enhancement of semi-volatile materials in the outdoor particulate matter. Indoor/outdoor ratios for PM2.5 were generally higher at the trafficked site than the residential site, but for particle number were generally lower, reflecting the different chemical composition and size distributions of particles at the two sites.

Systematic approach on the fabrication of Co doped ZnO semiconducting nanoparticles by mixture of fuel approach for Antibacterial applications

Zinc oxide (ZnO) is a wide band gap semiconductor (3.2eV) with a high exciton binding energy (60meV), where it has wide applications in advanced spintronic devices. The theoretical prediction of room temperature ferromagnetism and also antibacterial activity will be possible through the investigation of diluted magnetic semiconductors (DMS), such as transition metal doped ZnO, especially Cobalt doped ZnO. The aim of the work is the synthesis of Cobalt (Co) doped ZnO nanopowders were prepared Zn1−xCoxO (0⩽x⩾0.09) nanopowders from Sol–Gel auto combustion method have been synthesized with precursors such as Zinc and Cobalt nitrates with the assistance Ammonium acetate & Urea as fuel by increasing the cobalt concentration in zinc oxide and their structural, morphological, optical, Thermal, magnetic and antibacterial properties were studied by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Transmission Electron microscope (TEM), UV–visible spectroscopy, thermo gravimetric/differential thermal analysis (TG/DTA) and vibrating sample magneto meter (VSM). From the antibacterial studies, against gram positive Bacillus subtilis bacteria is most abundant bacteria in soil and indoor atmosphere, which affects the stored spintronic devices so that the devices should be made with antibacterial activity of DMS like Co doped ZnO. In this article is found that ZnO:Co nanopowders with higher Co doping level (0.07 and 0.09wt%) exhibit good antibacterial efficiency. The magnetization curves obtained using vibrating sample magnetometer (VSM) show a sign of strong room temperature ferromagnetic behavior when the Co doping level is 0.05wt% and a weak room temperature ferromagnetic behavior Co doping level is below 0.07wt%, and also they found to exhibit antiferromagnetic and paramagnetic properties, when the Co doping levels are 0.07 and 0.09wt%, respectively, to enhance and increase the special magnetic and antibacterial property for sophisticated devices for the sustainable technologies.

Application of automated electrical resistance sensors for measurement of corrosion rate of copper, bronze and iron in model indoor atmospheres containing short-chain volatile carboxylic acids

The corrosion rate of copper and bronze Cu-8wt.%Sn increased rapidly when the concentration of formic or acetic acid in air reached about 300ppb at 80% relative humidity (RH) and a temperature of 20°C. It decreased slowly during the several days after pollutant removal due to the slow rate of pollutant desorption from the metal surfaces. Corrosion of these metals was barely affected by the acids at RH up to 60%. For iron, the critical concentration of formic acid in air which led to surface activation at 80% RH was between 1000 and 1590ppb.

Daily and seasonal radon variability in the underground low-background laboratory in Belgrade, Serbia

Radon time-series analysis, based on the short-term indoor radon measurements performed worldwide, shows two main periodicity: daily and seasonal. The information obtained from time series of the measured radon values is the results of the complex radon dynamics that arises from the influence of the large number of different parameters (the state of the indoor atmosphere (temperature, pressure and relative humidity, aerosol concentration), the exchange rate between indoor and outdoor air and so on). In this paper we considered daily radon variability in the underground low-background laboratory in Belgrade, Serbia. The results are originated from the radon time-series analysis based on the 3 y of the continuous short-term indoor radon measurements. At the same time, we obtained the time series of the temperature, pressure and relative humidity in the laboratory. We also tried to find the correlation between different time series.

Disinfestation of historical buildings – corrosion evaluation of four fumigants on standard metals

This study aims for providing adapted solutions for disinfestation of cultural buildings and collections in place of the use of methyl bromide, ozone depleting substance recently forbidden. It reports on a two-step corrosion test assessing the corrosive activity (corrosivity) of alternative fumigants. Four candidate fumigants are investigated: sulfuryl fluoride (SF), dimethyl disulfide (DMDS), phosphine (PH 3 ) and cyanogen (EDN) in conjunction with five standard metals: silver (Ag), tin (Sn), iron (Fe), lead (Pb) and copper (Cu). The applied procedure is detailed including the fumigation protocol and the description of a specific electrochemical twin cells device. The surface evolution of metallic coupons after fumigation treatments and after hygrothermal ageing (35 °C, 95% RH) is compared to a blank reference series (indoor atmosphere). Results from colorimetry and electrochemical (linear sweep voltammetry) measurements, completed by Raman spectroscopy investigation show that each fumigant differently affects metals both in amplitude (amount of surface species) and in composition (nature of corrosion products). Sulfuryl fluoride (SF) can be recommended for cultural heritage but care has to be taken in presence of Pb, Sn and Cu. DMDS is also a good alternative candidate, however, it affects greatly Cu coloration and promotes Pb corrosion. Phosphine (PH 3 ) is dramatic for Cu and has to be avoided while the efficient biocide EDN increases corrosion of Ag and Cu even if low color variation is observed. It is strongly recommended for selecting the fumigant to properly identify the metallic artefacts prior fumigation.

In2O3-based micro gas sensor for detecting NO x gases

In this study, NOx micro gas sensors for monitoring the indoor atmosphere of automobile were fabricated using MEMS (microelectromechanical system) technology and a sol-gel process. The sensing electrode and micro heater were designed to have a co-planar typed structure in a Pt thin film layer. The thermal characteristics of a micro heater array were analyzed using a finite element method (FEM). The chip size of the gas sensor was approximately 2 mm × 2 mm. Indium oxide as a sensing material for NOx gas was synthesized by a sol-gel process with indium isopropoxide as a precursor. Field emission Scanning electron microscopy and x-ray diffraction showed that particle size of the synthesized In2O3 was approximately 17–45 nm. The maximum gas sensitivity as the relative resistance (Rs = Rgas/Rair) was observed at 275°C with a value of 8.0 at 1 ppm NO2 gas. The response (80% saturation) and recovery times were within 1 min. The sensing properties of NO2 gas exhibited linear behavior with increasing gas concentration. The sensing mechanism of the gas sensor was explained by the variations in the electron depletion layers and the adsorption of gas molecules on the In2O3 particle surface. These results suggest that in the future, MEMS-based gas sensors can be used as automotive-exhaust-gas sensors.

The Oxidative Capacity of Indoor Atmospheres

The Oxidative Capacity of Indoor Atmospheres

DEHP, DEP and DBP Exposure Analysis using Urinary Metabolites of Gyonggi Province University Students

Objectives: Phthalates are used as plasticizers in polyvinyl chloride (PVC) plastics. As phthalate plasticizers are not chemically bound to the PVC, they can leach, migrate or evaporate into indoor air and atmosphere, foodstuffs, other materials, etc. Therefore, humans are exposed through ingestion, inhalation, and dermal exposure over their entire lifetime, including during intrauterine development. In particular, university students have a great number of opportunities to contact products including phthalates during campus life (food packaging, body care products, cosmetic, lotions, aftershave, perfume etc.). The purpose of this study was to examine levels of phthalate exposure as undergraduate students begin to use pharmaceuticals and personal care products including phthalates. Methods: Phthalate metabolites, mono-ethyl phthalate (MEP), mono-n-butyl phthalate (MnBP), mono-isobutyl phthalate (MiBP), mono-2- ethylhexyl phthalate (MEHP), {(mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP}, and mono-(2-ethlyl-5-oxohexyl) phthalate (MEOHP} were examined. 80 urine samples collected from university students were analyzed using LC/MS/MS(API 4000, Applied Bioscience) with on-line enrichment and columnswitching techniques. This study was carried out at Y university located in Gyonggi Province from 2008 to 2011. Results: The detection limit of phthalate metabolites were 0.03 ng/mL for MEP, 0.11 ng/mL for MnBP, 0.08 ng/mL for MiBP, 0.93 ng/mL for MEHP, 0.19 ng/mL for MEOHP and 0.16ng/mL for MEHHP. MnBP showed the highest urinary levels (median: 31.6 ug/L, 24.8 ug/g creatinine (cr)). Concentrations were also high for MEHHP (median: 24.1 ug/L, 19.0 ug/g cr), followed by MEOHP (median: 22.8 ug/L, 17.9 ug/g cr). In individual cases, the maximum level reached up to 348 ug/L, and 291 ug/g cr, respectively. The urinary and creatinine adjusted levels of MEP were lower than those for DBP and DEHP metabolites, but were higher in 95th percentiles. As a result, the mean daily DEP intake value was 2.3 <TEX>${\mu}g/kg$</TEX> bw/day, 3.5 <TEX>${\mu}g/kg$</TEX> bw/day for DEHP and 4.9 <TEX>${\mu}g/kg$</TEX> bw/day for DBP. Conclusion: These students' phthalate exposure levels were below the international safe level set by the EU, but higher than the 2012 KFDA survey of the age group from 3 to 18.

Perceptive-cognitive aspects investigation in relation to indoor environment satisfaction collected from naturally ventilated multi-storey student accommodations in Malaysia

Investigation of occupant’s indoor environment influences can be identified through perceptive-cognitive aspects. Such an investigation leads to affective responses such as satisfied or dissatisfied, annoyed or not annoyed and hot or cold. This study investigates the perceptive-cognitive aspects of indoor environment among students who are staying in multi-storey accommodations in Klang Valley area, Malaysia. The students were asked to participate in the subjective survey in order to gather their indoor environment satisfaction votes. The objectives of this study are (1) to know how does the occupant of naturally ventilated multi-storey student accommodations respond to their indoor comfort whilst staying in an uncontrollable indoor atmosphere and (2) to identify what are the design features that contribute to the achievement of occupant’s overall indoor environment satisfaction. The main findings suggest that the uncontrollable indoor condition which occurred when occupants open their windows resulted in a more significant dissatisfaction vote toward indoor noise level in conjunction with warmer thermal sensation incidences. Moreover, despite the increasing indoor noise level recorded in rooms at higher floor levels, the findings show that room location, room orientation and shading ratio are not considered to influence the occupants’ overall indoor environment satisfaction and dissatisfaction.

Miniaturization of colorimetric and fluorimetric analyzers for the gaseous formaldehyde detection

Formaldehyde is a major pollutant of indoor air owing to its multiple sources (materials, combustion, painting, etc.). Based on a former in-house formaldehyde analyzer, two new miniaturized analyzers are being developped. The former analyzer was based on the reaction of formaldehyde with a selective derivative agent (fluoral-P) to form a fluorescent species (DDL). The analyzer measured concentrations of formaldehyde in 3 steps strongly coupled to each other: 1) the uptake of gaseous formaldehyde into an aqueous solution, 2) the selective derivatization of formaldehyde by reaction with fluoral-P, 3) the analysis of the reaction product by fluorescence spectroscopy. [1] For the next generation devices, new technologies are used for the uptake of gaseous formaldehyde and the detection. However, the reaction step remains unchanged. New molecules are in development in order to obtain better quantum efficiency. In one case, the detection is realized by colorimetry with the major benefit of no calibration requirement. In the other case, the detection is realized by fluorescence spectroscopy, the major advantage being a better and higher sensitivity than colorimetric detection. The former analyzer weighted 8 kg while future miniaturized analyzers will weigh less than 2 kg making them suitable for field analyses. These new analyzers will combine precision, selectivity towards formaldehyde, high speed analysis, information processing and communication into a single much smaller device. Finally, it will be necessary to validate the smooth running and the precision of these devices by comparison with the conventional technique of derivatization by DNPH coupled to analysis by HPLC/UV on synthetic air samples generated by a calibrated source of gaseous formaldehyde and also in real indoor atmospheres under various scenarios.

Photo-oxidation of Isoprene with Organic Seed: Estimates of Aerosol Size Distributions Evolution and Formation Rates

Indoor smog chamber experiments have been conducted to investigate the dynamics of secondary organic aerosol (SOA) formation from OH-initiated photo-oxidation of isoprene in the presence of organic seed aerosol. The dependence of the size distributions of SOA on both the level of pre-existing particles generated in situ from the photo-oxidation of trace hydrocarbons of indoor atmosphere and the concentration of precursor, has been investigated. It was shown that in the presence of high-level seed aerosol and low-level isoprene (typical urban atmospheric conditions), particle growth due to condensation of secondary organic products on pre-existing particles dominated; while in the presence of low-level seed aerosol and comparatively high-level isoprene (typical atmospheric conditions in rural region), bimodal structures appeared in the size distributions of SOA, which corresponded to new particle formation resulting from homogeneous nucleation and particle growth due to condensation of secondary organic products on the per-existing particles respectively. The effects of concentrations of organic seed particles on SOA were also investigated. The particle size distributions evolutions as well as the corresponding formation rates of new particles in different conditions were also estimated.

Determination of mechanisms and parameters which affect radon entry into a room

There are practically no direct techniques for measuring radon entry rate in the rooms. The suggested technique allows estimating such parameter under real conditions. The technique for radon diagnostic procedures including radon entry rate and air change rate assessment was proposed and tested in the field under various experimental conditions.The method consists of the continuous measurement of radon concentration, temperature and pressure difference between indoor and outdoor atmosphere. It was demonstrated that the study of dependence of radon entry rate on temperature difference ΔT between indoor and outdoor atmosphere allows to estimate the dominant radon entry mechanism – diffusion mechanism (absence of the dependence on ΔT) or convective (radon entry rate increase at ΔT increase). It was shown that simultaneous measurements of time series of radon concentration and pressure difference between building envelope and outdoor atmosphere allow assessing such room parameter as Effective Leakage Area.The approach applied in this paper to estimate the air change rate practically is not differing from tracer gas techniques when the constant gas entry rate is used. It was shown that radon could be used as kind of tracer gas to estimate the air change rate.Obtained measurement results for all buildings confirmed the seasonal variations of radon concentrations. A correlation of radon concentration and air change rate with outside temperature occurred in general.

High sensitivity electrical resistance sensors for indoor corrosion monitoring

It is essential that corrosion monitoring of indoor atmospheres be highly sensitive, especially when corrosion rates corresponding to the lowest standard corrosivity categories are supposed to be identified within one or a few days. The electrical resistance (ER) technique in combination with high sensitivity ER sensors enabled detection of corrosion loss on an atomic scale. The magnetron sputtering method was used to produce sensors equipped with 50 to 800 nm metallic track. The set of developed sensors represent a wide range of materials, e.g. copper, silver, iron, lead and bronze. Laboratory experiments have proven that copper and silver sensors respond to changes in relative humidity and temperature within minutes. Bronze and copper sensors are able to detect changes in concentrations of volatile organic acids, which are common pollutants of indoor atmospheres in museums.

Corrosion monitoring in archives by the electrical resistance technique

Abstract It is essential that corrosion monitoring of indoor atmospheres should be highly sensitive, especially, when corrosion rates corresponding to the lowest standard corrosivity categories are supposed to be identified within one or a few days. The electrical resistance technique in combination with high-sensitivity electrical resistance sensors enabled detection of a corrosion loss on an atomic scale. Case studies have demonstrated the sensors’ ability to timely inform the users about changes in the atmosphere quality. In confrontation with quartz crystal microbalance technique, resistometric sensors provided better explainable data.

Sensing of volatile organic compounds in indoor atmosphere and confined areas of industrial environments

A chemical vapour sensor working with a monochromatic light source and based on optical fibre coated with a thin siloxane polymer film has been developed for in situ monitoring of volatile organic compounds, such as ethylbenzene, xylene (o-xylene), heptane, octane, chloroform, carbon tetrachloride, ethanol and butanol in indoor atmosphere and confined areas of industrial environments. The sensor consists on a monomode optical fibre with an end surface coated with a thin polymeric film by dip-coating technique. The light source utilized was a stabilized laser diode at 1550 nm and the light power changes were measured with a photodiode. The sensor was tested for different VOCs and for different individual concentrations regarding stability, sensitivity, repeatability and reversibility of the analytical signal. The response and desorption time have been found to be 30 seconds and good reproducibility and accuracy have been also obtained. Finally, the analytical performance of the developed sensor was also evaluated and found adequate for actual monitoring on indoor atmospheres.

Air ion and pollution index variation for indoor and outdoor atmosphere at rural station Ramanandnagar (17°4′N 74°25′E) India

In the present study, the observation of indoor air ion concentration at a rural site has been carried out for the first time. These indoor observations are compared with outdoor air ion concentration. Net charge can be introduced into the atmosphere by processes such as combustion, rainfall and ultraviolet radiation. As compared to indoors, average air ions of both the polarities at outdoors are higher. Moreover, the air ion concentrations, experience large fluctuations during daytime, as compared to nighttime values. Positive and negative air ion concentrations are lower and uniform throughout the night both for indoor and outdoor conditions. Pollution index is more or less unity for outdoors in all-the-time period, which is good for human health. Due to limited sources of air ions indoors, it is observed that pollution index decreases from 00:00–02:00 hours and minimum is reached during 12:00–14:00 hours for indoors. During 00:00–02:00 hours, the indoor pollution index is 1.55, which is very harmful to human health.

Formaldehyde and Epigenetic Alterations: MicroRNA Changes in the Nasal Epithelium of Nonhuman Primates

Background: Formaldehyde is an air pollutant present in both indoor and outdoor atmospheres. Because of its ubiquitous nature, it is imperative to understand the mechanisms underlying formaldehyde-induced toxicity and carcinogenicity. MicroRNAs (miRNAs) can influence disease caused by environmental exposures, yet miRNAs are understudied in relation to formaldehyde. Our previous investigation demonstrated that formaldehyde exposure in human lung cells caused disruptions in miRNA expression profiles in vitro.Objectives: Using an in vivo model, we set out to test the hypothesis that formaldehyde inhalation exposure significantly alters miRNA expression profiles within the nasal epithelium of nonhuman primates.Methods: Cynomolgus macaques were exposed by inhalation to approximately 0, 2, or 6 ppm formaldehyde for 6 hr/day for 2 consecutive days. Small RNAs were extracted from nasal samples and assessed for genome-wide miRNA expression levels. Transcriptional targets of formaldehyde-altered miRNAs were computationally predicted, analyzed at the systems level, and assessed using real-time reverse transcriptase polymerase chain reaction (RT-PCR).Results: Expression analysis revealed that 3 and 13 miRNAs were dysregulated in response to 2 and 6 ppm formaldehyde, respectively. Transcriptional targets of the miRNA with the greatest increase (miR-125b) and decrease (miR-142-3p) in expression were predicted and analyzed at the systems level. Enrichment was identified for miR-125b targeting genes involved in apoptosis signaling. The apoptosis-related targets were functionally tested using RT-PCR, where all targets showed decreased expression in formaldehyde-exposed samples.Conclusions: Formaldehyde exposure significantly disrupts miRNA expression profiles within the nasal epithelium, and these alterations likely influence apoptosis signaling.

Emission characteristics of air pollutants from incense and candle burning in indoor atmospheres

Volatile organic compounds (VOCs) and particles emitted by incense sticks and candles combustion in an experimental room have been monitored on-line and continuously with a high time resolution using a state-of-the-art high sensitivity-proton transfer reaction-mass spectrometer (HS-PTR-MS) and a condensation particle counter (CPC), respectively. The VOC concentration-time profiles, i.e., an increase up to a maximum concentration immediately after the burning period followed by a decrease which returns to the initial concentration levels, were strongly influenced by the ventilation and surface interactions. The obtained kinetic data set allows establishing a qualitative correlation between the elimination rate constants of VOCs and their physicochemical properties such as vapor pressure and molecular weight. The emission of particles increased dramatically during the combustion, up to 9.1(±0.2) × 10(4) and 22.0(±0.2) × 10(4) part cm(-3) for incenses and candles, respectively. The performed kinetic measurements highlight the temporal evolution of the exposure level and reveal the importance of ventilation and deposition to remove the particles in a few hours in indoor environments.

Microbial communities adhering to the obverse and reverse sides of an oil painting on canvas: identification and evaluation of their biodegradative potential

In this study, we investigated and compared the microbial communities adhering to the obverse and the reverse sides of an oil painting on canvas exhibiting signs of biodeterioration. Samples showing no visible damage were investigated as controls. Air samples were also analysed, in order to investigate the presence of airborne microorganisms suspended in the indoor atmosphere. The diversity of the cultivable microorganisms adhering to the surface was analysed by molecular techniques, such as RAPD analysis and gene sequencing. DGGE fingerprints derived from DNA directly extracted from canvas material in combination with clone libraries and sequencing were used to evaluate the non-cultivable fraction of the microbial communities associated with the material. By using culture-dependent methods, most of the bacterial strains were found to be common airborne, spore-forming microorganisms and belonged to the phyla Actinobacteria and Firmicutes, whereas culture-independent techniques identified sequenced clones affiliated with members of the phyla Actinobacteria and Proteobacteria. The diversity of fungi was shown to be much lower than that observed for bacteria, and only species of Penicillium spp. could be detected by cultivation techniques. The selected strategy revealed a higher microbial diversity on the obverse than on the reverse side of the painting and the near absence of actively growing microorganisms on areas showing no visible damage. Furthermore, enzymatic activity tests revealed that the most widespread activities involved in biodeterioration were esterase and esterase lipase among the isolated bacterial strains, and esterase and N-acetyl-β-glucosaminidase among fungi strains.

Measurement of volatile organic compounds emitted in libraries and archives: an inferential indicator of paper decay?

BackgroundA sampling campaign of indoor air was conducted to assess the typical concentration of indoor air pollutants in 8 National Libraries and Archives across the U.K. and Ireland. At each site, two locations were chosen that contained various objects in the collection (paper, parchment, microfilm, photographic material etc.) and one location was chosen to act as a sampling reference location (placed in a corridor or entrance hallway).ResultsOf the locations surveyed, no measurable levels of sulfur dioxide were detected and low formaldehyde vapour (< 18 μg m-3) was measured throughout. Acetic and formic acids were measured in all locations with, for the most part, higher acetic acid levels in areas with objects compared to reference locations. A large variety of volatile organic compounds (VOCs) was measured in all locations, in variable concentrations, however furfural was the only VOC to be identified consistently at higher concentration in locations with paper-based collections, compared to those locations without objects. To cross-reference the sampling data with VOCs emitted directly from books, further studies were conducted to assess emissions from paper using solid phase microextraction (SPME) fibres and a newly developed method of analysis; collection of VOCs onto a polydimethylsiloxane (PDMS) elastomer strip.ConclusionsIn this study acetic acid and furfural levels were consistently higher in concentration when measured in locations which contained paper-based items. It is therefore suggested that both acetic acid and furfural (possibly also trimethylbenzenes, ethyltoluene, decane and camphor) may be present in the indoor atmosphere as a result of cellulose degradation and together may act as an inferential non-invasive marker for the deterioration of paper. Direct VOC sampling was successfully achieved using SPME fibres and analytes found in the indoor air were also identified as emissive by-products from paper. Finally a new non-invasive, method of VOC collection using PDMS strips was shown to be an effective, economical and efficient way of examining VOC emissions directly from the pages of a book and confirmed that toluene, furfural, benzaldehyde, ethylhexanol, nonanal and decanal were the most concentrated VOCs emitted directly from paper measured in this study.