Indoor Contaminants Research Articles

Mitigation of indoor air pollutants using Areca palm potted plants in real-life settings.

Deterioration of indoor air quality (IAQ) has become a serious concern as people spend lots of time indoors and prolonged pollution exposure can result in adverse health outcomes. Indoor plants can phytoremediate a wide variety of indoor contaminants. Nonetheless, few experiments have demonstrated their efficacy in real-time environments. Therefore, the present study aims to experimentally assess the efficiency of Areca palm potted plants in phytoremediation of primary indoor air pollutant viz. total volatile organic compounds (TVOCs), carbon dioxide (CO2), and carbon monoxide (CO) levels from real-world indoor spaces, for the first time. Four discrete naturally ventilated experimental sites (I-IV) situated at the Council of Scientific and Industrial Research- Institute of Himalayan Bioresource Technology (CSIR-IHBT) were used. For over a period of 4months, the sites were monitored using zero plants as a control (1-4week), three plants (5-8week), six plants (9-12week), and nine plants (13-16week), respectively. Present results indicate that Areca palm potted plants can effectively reduce the TVOCs, CO2, and CO levels by 88.16% in site IV, 52.33% and 95.70% in site III, respectively. The current study concluded that Areca palm potted plants offer an efficient, cost-effective, self-regulating, sustainable solution for improving indoor air quality and thereby human well-being and productivity in closed and confined spaces.

Burnout: really, really tired of COVID

Burnout: really, really tired of COVID

Tracing indoor contaminant release location based on local mean residual-life-time of air

Even in case ventilation system is operating in optimal fashion, indoor air quality could be varied depending on the indoor contaminant release occasions. Thus, accurate and rapid identification of contaminant source locations in indoor environment is critical for occupants’ health as well as building safety and integrity. This study presented a novel method to locate indoor contaminant source using local mean residual-life-time (LMR). Based on the theoretical definition of LMR, a characteristic quantitative relationship between the LMR at source location and the contaminant concentration profile of a room was derived and assessed through two stages of studies: experimental and numerical explorations. In the experiments, by changing contaminant release location under limited condition, the LMR at the source location and the contaminant concentration profile of a test chamber were measured. Then, the outcomes were examined to verify whether the derived equation was established in the chamber. Computational Fluid Dynamics (CFD) technique was also used to make up for the experimental limitations. CFD simulations were carried out to analyze the validity of the equation in response to different release locations of the contaminant in a more complex physical environment by obtaining high-resolution information. Both experimental and numerical results showed that the presented equation was well established and could be used to locate indoor contaminant source even in non-ideal situation or in complicated spaces.

An Advanced Dual‐Function MnO2‐Fabric Air Filter Combining Catalytic Oxidation of Formaldehyde and High‐Efficiency Fine Particulate Matter Removal

AbstractComprehensive treatment of indoor contaminants such as volatile organic compounds (VOCs) and fine particulate matter (PM2.5) using transition metal oxide catalysts or functional fibrous filters has gained substantial attention recently. However, coupling VOC oxidation catalysts into high‐performance filter systems remains a challenge. Herein, an overall solution to strongly bind manganese dioxide (MnO2) nanocrystals onto polypropylene (PP) nonwoven fabrics is provided. For the first time, uniform heterogeneous nucleation and growth of MnO2 onto PP nonwoven fabrics using intermediate inorganic nucleation films, including Al2O3, TiO2, and ZnO, formed conformally on the fabrics via atomic layer deposition (ALD) are demonstrated. How different ALD thin films influence the crystallinity, morphology, surface area, and surface oxygen species of the MnO2 grown ALD‐coated PP fibers is further investigated. In addition to uniformity and integrity, ZnO thin films give rise to MnO2 crystals with the largest fraction of available surface oxygen, enabling 99.5% catalytic oxidation of formaldehyde within 60 min. Moreover, the metal oxide filters provide excellent PM removal efficiencies (ePM), achieving ePM2.5 90% and ePM10 98%, respectively, making the approach an outstanding method to produce fully dual‐functional filtration media.

Legacy and emerging organophosphorus flame retardants and plasticizers in indoor microenvironments from Guangzhou, South China

Indoor dust has been extensively used for assessment of indoor contamination, especially for semi-volatile organic compounds (SVOCs). In the present study, the occurrence of four groups of SVOCs, i.e. organophosphorus flame retardants (PFRs), emerging PFRs (ePFRs), legacy phthalates (LPs), and alternative plasticizers (APs), was investigated in the indoor dust and air collected from floors, table surfaces, windows, and air conditioner (A/C) filters in bedrooms and offices in Guangzhou, South China. In bedrooms, A/C filter dust showed the highest median concentrations of PFRs (4670 ng/g) and ePFRs (586 ng/g), whilst the highest median concentrations of LPs and APs were found in floor (240,880 ng/g) and window dust (157,160 ng/g), respectively. In offices, A/C filter dust showed the highest median concentrations for PFRs (6750 ng/g) and APs (504,520 ng/g), while the highest ePFR median level was found in PC table dust (5810 ng/g) and LPs in floor dust (296,270 ng/g). Median air concentrations of PFRs, ePFRs, LPs, and APs were measured at 4.6, 0.12, 399, and 25 ng/m3 in bedrooms, and at 8.0, 0.05, 332, and 43 ng/m3 in offices, respectively. Tris(1-chloro-iso-propyl) phosphate (TCIPP) was the predominant PFRs/ePFRs in both dust and air. Di(2-ethylhexyl) phthalate (DEHP), di-iso-decyl phthalate (DIDP) and di-iso-nonyl phthalate (DINP) were the main LP/AP compounds in dust, whilst di-iso-butyl phthalate (DIBP) and di-n-butyl phthalate (DNBP) were the most abundant LPs/APs in air. A significant correlation (p < 0.05) was found between dust and air levels for chemicals with log Koa < 14, indicating that equilibrium was achieved for these chemicals but not for those with log Koa > 14. Among the investigated human exposure pathways (i.e. dust ingestion, dermal absorption, and air inhalation), dust ingestion was the predominant one for all chemicals. Human exposures of this magnitude to these chemicals through the investigated pathways was unlikely to present a health risk in the present study.

An Emerging Frontier: Metal(loid) Soil Pollution Threat Under Global Climate Change.

An Emerging Frontier: Metal(loid) Soil Pollution Threat Under Global Climate Change.

Sustainability of SARS-CoV-2 in aerosols: should we worry about airborne transmission?

Sustainability of SARS-CoV-2 in aerosols: should we worry about airborne transmission?

Occurrence of Halogenated Pollutants in Domestic and Occupational Indoor Dust.

The occurrence of halogenated organic pollutants in indoor dust can be high due to the presence of textile, electronic devices, furniture, and building materials treated with these chemicals. In this explorative study, we focused on emerging organic pollutants, such as novel brominated flame retardants (nBFRs) and some perfluoroalkyl substances, together with legacy polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (BDEs) in settled dust collected in houses and workplaces such as one office and two electrotechnical and mechanical workshops. The total contribution of the investigated pollutants was lower in house and in office dusts except for few nBFRs (such as bis (2-ethylhexyl)-3,4,5,6-tetrabromo-phthalate at a concentration of 464.5 ng/g in a house and hexachlorocyclopentadienyldibromocyclooctane at 40.4 ng/g in the office), whereas in electrotechnical and mechanical workshops a high incidence of PCBs, BDEs, and nBFRs occurred (for example, BDE 209 at a concentration of 2368.0 ng/g and tetrabromobisphenol A at 32,320.1 ng/g in electrotechnical and mechanical workshops). Estimated daily intakes were also calculated, showing that domestic and occupational environments can lead to a similar contribution in terms of human exposure. The higher exposure contribution was associated to nBFRs, whose EDIs were in the range of 3968.2–555,694.2 pg/kg bw/day. To provide a complete view about the indoor contamination, in this investigation, we also included polycyclic aromatic hydrocarbons (PAHs) and their oxygenated and nitrated derivatives. Definitely, dust collection represents a simple, fast, and cost-effective sampling and dust contamination level can be a useful indicator of environment healthiness. Besides, the presented method can be a smart tool to provide a time and money saving technique to characterize 99 pollutants thanks to a single sample treatment.

Solutions to mitigate the impact of measurement noise on the air pollution source strength estimation in a multi-zone building

Indoor contaminants jeopardize people’s health and may even cause serious consequences under extreme conditions. Therefore, the prompt and accurate identification of indoor airborne contaminant characteristics is significant for indoor health and safety. In this paper, we used an inverse Markov chain model, combined with the regularization proposed in our previous research, to identify periodic source strength under steady airflow in a multi-zone building. The impact of different measurement noise (0.05%, 0.1%, 0.2%) on the inverse results was investigated. The results showed that the greater the noise, the greater the oscillation of the inverse result. Furthermore, we also investigated the effect of adjusting the calculation time step (5 s, 10 s, 20 s, 30 s) and adding digital filters (Sliding window filter and Butterworth low pass filter) on the inverse source release rate. The results showed that properly increasing the calculation time step can reduce the impact of measurement noise. The root mean square error (RMSE) of the inverse source strength with 0.1% noise decreased from 22.89 under a 5-s time step to 0.9793 under a 30-s time step. It was also found that adding digital filters could reduce the oscillation of the inverse source results, and the performance of the filters also depends on the calculation time steps.

Characterisation of fungal and bacterial dynamics in an active green wall used for indoor air pollutant removal

Indoor air quality (IAQ) is of growing public health concern which has prompted the use of plants to phytoremediate air pollution in interior spaces. Active green walls are emerging as a means of reducing indoor contaminants and have demonstrated efficacy comparable to conventional air filtering technologies. However, the use of active airflow through organic substrates has the potential to emit bioaerosols into the surrounding environment, where the potential risk to human health is largely unknown. In this study, we demonstrate that two indoor green walls (with and without active airflow) contribute significantly to the ambient fungal load, however concentrations remained well below WHO safety guidelines. Bacterial dynamics within the rhizosphere/substrate of the operational botanical biofilters displayed variability across plant species. Phyla-wide distribution generally aligned with previous literature; however, differences from those previously reported were observed at the genus level, possibly due to geographic location, substrate composition, or plant species selection. Targeted assessment of Legionella aerosol contamination, an under-addressed potential pathogen for these active systems, yielded no positive identification during the sampling period. We conclude that active green walls host a unique bacterial profile and do not emit harmful levels of fungal propagules or pose significant risk of aerosolised Legionella species, provided systems are well monitored and maintained.

Multiple Stressor Effects of Radon and Phthalates in Children: Background Information and Future Research

The present paper reviews available background information for studying multiple stressor effects of radon (222Rn) and phthalates in children and provides insights on future directions. In realistic situations, living organisms are collectively subjected to many environmental stressors, with the resultant effects being referred to as multiple stressor effects. Radon is a naturally occurring radioactive gas that can lead to lung cancers. On the other hand, phthalates are semi-volatile organic compounds widely applied as plasticizers to provide flexibility to plastic in consumer products. Links of phthalates to various health effects have been reported, including allergy and asthma. In the present review, the focus on indoor contaminants was due to their higher concentrations and to the higher indoor occupancy factor, while the focus on the pediatric population was due to their inherent sensitivity and their spending more time close to the floor. Two main future directions in studying multiple stressor effects of radon and phthalates in children were proposed. The first one was on computational modeling and micro-dosimetric studies, and the second one was on biological studies. In particular, dose-response relationship and effect-specific models for combined exposures to radon and phthalates would be necessary. The ideas and methodology behind such proposed research work are also applicable to studies on multiple stressor effects of collective exposures to other significant airborne contaminants, and to population groups other than children.

Analysis of health impact assessment to outdoor and indoor air pollution in a prototype building in Madrid (Spain)

People spend major part of their time inside places such as homes and offices, so it is very important to know the indoor and outdoor pollution in this type of studies. The atmospheric dispersion model WRF/Chem is used to know the outdoor pollution and meteorological conditions with high spatial (1 km) and temporal (1-hour) resolution and the building energy model EnergyPlus to simulate the indoor contaminants. EnergyPlus model is used to investigate the dynamic behaviour of pollutants with a single package using a multizone approach. 2016 year is used for the simulations with hourly outputs. Outdoor and indoor pollutions are linked to through the simulated infiltration process. The evaluation of outdoor, indoor air quality and human health effects was carried out considering different exposure profiles, for people working and living in an office and house located in the same building in the Madrid city center. The study takes into account different ventilation modes in the building and indoor emission scenarios (oven for heating, cooking, photocopy machine, smoke cigarettes). Health impact assessment considered mortality and hospital admissions, associated with exposure to PM2.5 and NO2 taking into account the differences between the exposure profiles, which have been used to describe the time activity patterns of the people. The health impacts of emitting sources are highest in the warm months due to the operation of the air conditioning system. The health impact of indoor emission sources is higher than the outdoor pollution. People in the zone where the emitting sources are located would experience a mortality and morbidity of 2.5 times more than in the non-emitting zones.

Temporal trends in concentrations of legacy and novel brominated flame retardants in house dust from Birmingham in the United Kingdom

Concentrations of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCDD), tetrabromobisphenol-A (TBBPA) and two potential replacements decabromodiphenylethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) were measured in dust samples collected from 14 homes across Birmingham (UK). Concentrations were compared with those from the same city in previous studies to ascertain any temporal changes and to assess the effects of legislative restrictions. The average ∑HBCDDs concentration (46,000 ng/g; median = 280 ng/g) included the highest dust concentration recorded globally (570,000 ng/g). This is despite the listing of HBCDD under the Stockholm Convention in 2013, demonstrating that decreases in indoor contamination will likely be slow as existing sources are gradually discarded. In contrast, concentrations of BDE-47 (mean = 5.7 ng/g; median = 0.93 ng/g) and BDE-99 (mean = 11 ng/g; median = 2.9 ng/g) were significantly lower than in all previous (p < 0.01) studies in the same city since 2006, suggesting restrictions on the Penta-BDE formulation have been effective. The average BDE-209 concentration (4800 ng/g; median = 1600 ng/g) is lower than the peak average concentration, which was observed in 2007 (280,000 ng/g), however this is not a significant decline, probably due to the later imposition of Deca-BDE restrictions compared to those on Penta-BDE. Decreases in PBDE concentrations have coincided with a significant (p < 0.01) increase in DBDPE concentrations (average = 1500 ng/g; median = 660 ng/g) since 2014, suggesting its use as a replacement flame retardant for Deca-BDE. While no significant change was detected for BTBPE (average 11 ng/g; median = 0.84 ng/g in this study); concentrations of TBBPA (average = 34 ng/g; median = 35 ng/g) were significantly lower (p < 0.05) than in 2007 (average 62 ng/g). The decreases observed in PBDE concentrations, demonstrates that legislation has been effective in reducing the commercial use of PBDEs, however this has coincided with increases of alternative flame retardants such as DBDPE.

A Methodology for Modeling Photocatalytic Reactors, Application to the Degradation of Formaldehyde

This article dealt with the photocatalytic oxidation of formaldehyde, a representative indoor contaminant contained in air. A numerical model was developed for analyzing the degradation of formalde...

TVOCs and PM 2.5 in Naturally Ventilated Homes: Three Case Studies in a Mild Climate

In southern Europe, the present stock of social housing is ventilated naturally, with practice varying in the different seasons of the year. In winter, windows are kept closed most of the day with the exception of short periods for ventilation, whereas the rest of the year the windows are almost permanently open. In cold weather, air changes depend primarily on the air infiltrating across the envelope and when the temperature is warm, on the air flowing in through open windows. CO2, PM2.5, and TVOC concentration patterns were gathered over a year’s time in three social housing developments in southern Europe with different airtightness conditions and analyzed to determine possible relationships between environmental parameters and occupants’ use profiles. Correlations were found between TVOC and CO2 concentrations, for human activity was identified as the primary source of indoor contaminants: peak TVOC concentrations were related to specific household activities such as cooking or leisure. Indoor and outdoor PM2.5 concentrations were likewise observed to be correlated, although not linearly due to the presence of indoor sources. Ventilation as presently practiced in winter appears to be insufficient to dilute indoor contaminants in all three buildings, nor does summertime behavior guarantee air quality.

Indoor air concentrations of carbon dioxide (CO2), nitrogen dioxide (NO2), and ozone (O3) in multiple healthcare facilities.

This study evaluates indoor air concentrations of CO2, NO2, and O3 and their relationship to other indoor environmental factors in facilities with occupants susceptible to air contaminants, such as hospitals, senior specialized hospitals, elderly care facilities, and postnatal care centers. Indoor air samples were collected from 82 indoor facilities in South Korea and organized by region. Spearman's correlation and Kruskal-Wallis analyses were employed to examine the relationship among and differences between contaminants in the indoor facilities and indoor/outdoor differences of NO2 and O3 concentrations. Significant correlations were found between CO2 and NO2 concentrations (r2 = 0.176, p < 0.01), as well as NO2 and O3 concentrations (r2 = - 0.289, p < 0.0001). The indoor/outdoor concentration ratios in the indoor facilities were 0.73 for NO2 and 0.25 for O3. CO2 and NO2 displayed the highest mean concentrations during spring, while O3 displayed the highest and lowest mean concentrations during fall and summer, respectively. The calculated hazard quotient (HQ) for NO2 was higher than the acceptable level of 1 in postnatal care centers, thus posing a health risk for children. Study results indicate that efficient ventilation is required to reduce indoor contaminants in multiple healthcare facilities. This study provides a novel approach toward health risk assessment for indoor facilities with susceptible occupants on a large geographical scale.

Sex-specific behavioral effects following developmental exposure to tetrabromobisphenol A (TBBPA) in Wistar rats

Tetrabromobisphenol A (TBBPA) has become a ubiquitous indoor contaminant due to its widespread use as an additive flame retardant in consumer products. Reported evidence of endocrine disruption and accumulation of TBBPA in brain tissue has raised concerns regarding its potential effects on neurodevelopment and behavior. The goal of the present study was to examine the impact of developmental TBBPA exposure, across a wide range of doses, on sexually dimorphic non-reproductive behaviors in male and female Wistar rats. We first ran a pilot study using a single TBBPA dose hypothesized to produce behavioral effects. Wistar rat dams were orally exposed using cookie treats to 0 or 0.1 mg TBBPA/kg bw daily from gestational day (GD) 9 to postnatal day (PND) 21 to assess offspring (both sexes) activity and anxiety-related behaviors. Significant effects were evident in females, with exposure increasing activity levels. Thus, this dose was used as the lowest TBBPA dose in a subsequent, larger study conducted as part of a comprehensive assessment of TBBPA toxicity. Animals were exposed to 0, 0.1, 25, or 250 mg TBBPA/kg bw daily by oral gavage starting on GD 6 through PND 90 (dosed dams GD 6 – PND 21, dosed offspring PND 22 – PND 90). Significant behavioral findings were observed for male offspring, with increased anxiety-like behavior as the primary phenotype. These findings demonstrate that exposure to environmental contaminants, like TBBPA, can have sex-specific effects on behavior highlighting the vulnerability of the developing brain.

Role of O3 in the removal of HCHO using a DC streamer plasma

Formaldehyde is one of the most common volatile organic compounds and indoor contaminant, and one known to cause a variety of health problems. This paper proposes a streamer discharge reactor with negative or positive discharge for formaldehyde removal. The removal of HCHO and the simultaneous production of O3 in a DC streamer plasma were investigated. The performances of the positive and negative discharges were compared. The electrical characteristics such as U-I characteristics, discharge pattern, and power source efficiency were studied, and the reaction results were evaluated by O3 production, HCHO removal, and energy yield. Optical emission spectra were used to characterize the streamer and reactive species produced. A maximum HCHO removal rate of 78% was achieved at a specific energy density of 1700 J l−1. Results suggest that the positive streamer is better at producing O3 and oxidizing HCHO, compared to the negative counterpart. For the positive streamer plasma, the G-values of ozone production and formaldehyde decomposition are 0.59 molecules per 100 eV and 0.035 molecules per 100 eV, respectively. Interestingly, the production of O3 and degradation of HCHO were found to be simultaneous but quasi-individual processes. Both reactions were controlled by the generation of O atoms, however they consumed O atoms independently. The active species of OH, H and O radicals were observed, which had contribution to the degradation of formaldehyde. Finally, the reaction mechanism and most possible reaction pathways for the two processes were discussed.

Radiocesium concentration in indoor air during residential house cleaning in Fukushima Dai-ichi nuclear power plant evacuation areas

After the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, outdoor decontamination was conducted by the Japanese Government, whereas indoor contamination was the responsibility of individual residents. However, no data exist regarding 137Cs exposure during indoor cleaning. Therefore, indoor 137Cs radioactivity concentrations in indoor air were determined during cleaning in 60 houses within the evacuation area near the FDNPP, Fukushima Prefecture, Japan. Radiocesium activity concentrations per cubic meter of indoor air during dusting (mean ± SD (median)) was 6.8 ± 7.9 (4.7) and 1.6 ± 2.7 (0.78) Bq/m3 for all aerodynamic diameter of aerosol particle and PM2.5, respectively. Radiocesium activity concentrations in indoor air decreased with decreasing the aerodynamic diameter of aerosol particles (mean: 0.099, 0.22, 0.41, 0.92, 2.2, and 2.9 Bq/m3 for the aerodynamic diameter of <0.25, 0.25–0.5, 0.5–1.0, 1.0–2.5, 2.5–6.6, and >6.6 μm, respectively) and was inversely proportional to the square of the distance from the FDNPP. Indoor 137Cs radioactivity concentrations were significantly higher during dusting than during vacuuming with either a cyclone handy cleaner or a normal vacuum cleaner. The mean deposited activities in tracheobronchial and alveolar regions was estimated to be 1.9 and 2.8 Bq, respectively, during a 2-h dusting period in the studied houses. For values below the detection limit, half of the detection limit was used for calculating the means and SDs.

사물인터넷 기반 실내환경 측정 센서 모듈 개발

The purpose of the study is to develop an IoT sensor module for environmental measurement that can compare indoor and outdoor contamination. Low-cost and high-performance indoor environmental devices have been developed for easy access by researchers. The results as follows: The products used the Aduino Uno R3 with outstanding scalability and affordability. Performance verification shows the same trend of Fine dust concentration, Temperature and humidity error rate were 4.08% and 4.96% respectively, Air flow error rate is 4.58%. Therefore, the sensor modules developed in this study can be applied indoor the building for environmental measurement and are easily accessible to other researchers.