Indoor Environmental Pollution Research Articles

Development of a green microextraction procedure for determining polyaromatic hydrocarbons in electronic equipment plastics

The global proliferation of electronic devices, driven by technological advancements, has led to the release of organic pollutants from the plastic components of these devices, particularly in indoor environments. Among these pollutants, polycyclic aromatic hydrocarbons (PAHs), which are emitted into the air from plastic components, play a critical role in the field of indoor environment pollution. Consequently, effectively monitoring the PAH content in plastics used in electronic equipment is crucial for preventing indoor contamination.In this study we aimed to develop a fast, inexpensive, easy, and environmentally friendly analysis method for determining PAH content in plastic equipment. A dispersive liquid liquid microextraction (DLLME) combined with solidified organic drop (SFO) microextraction technique was developed.Considering the eleven number of parameters that can affect the signal in the DLLME-SFO method, Plackett Burmann's design was applied to select the most three impactful parameters for 18 PAH species. A Box-Behnken experimental design was also applied to optimize the identified parameters. The optimal conditions for the most influential parameters such as solvent type, pH, and the sample weight were identified as 1-dodecanol, 12 and 0.24 g, respectively.The proposed method was validated under these optimized conditions, yielding low detection limits ranging from 0.004 to 0.11 ng mL−1. The calibration curves were linear with correlation coefficients above 0.98 and relative standard deviation (RSD) values ranging from 2.4% to 20%. This method was successfully applied to analyze PAH content in the plastic components of electronic devices. The extraction technique developed in this study is a newly developed technique and has not been previously used to analyze organic pollutants that may be present in electronic equipment plastic.

Using computed tomography to diagnose chronic frontal sinusitis in the skeletal remains of a post-medieval Dutch rural community (AD 1829–1866)

Chronic frontal sinusitis (CFS) has afflicted humanity throughout history and continues to be a significant global health issue today. In bioarchaeology, sinusitis is often diagnosed through the identification of bone alterations within the maxillary sinus cavities by macroscopic and/or endoscopic examination. However, due to the inaccessible nature of frontal sinuses, CFS specifically has not been studied extensively archaeologically yet. This paper aims to demonstrate the effectiveness of diagnosing CFS through computed tomography (CT), highlighting the potential of radiographical imaging for future advancements in paleopathological research.We conducted a CT examination of 41 crania from the rural community of Middenbeemster, the Netherlands (AD 1829–1866) to assess the presence of CFS. Criteria for identifying CFS included bone formation and/or thickening of the sinus walls. Our analysis revealed that 14 individuals (34.1%) exhibited signs of CFS in one or both frontal sinuses. We found that males exhibited a slightly higher CFS prevalence (38%) than females (32%), although no significant correlation between sex and sinusitis occurrence was found. This lack of correlation suggests equal exposure to risk factors (e.g., indoor air quality, environmental pollution, allergens, and cold weather) among both sexes.To our knowledge, this study is the first of its kind to confirm the presence of CFS through CT scanning in an archaeological skeletal collection. It demonstrates that computed tomography allows for a straightforward and non-destructive detection of sinusitis in archaeological assemblages. Considering the currently limited bioarchaeological research on frontal sinusitis, our findings should be considered relevant and promising for future osteoarcheological studies on upper respiratory diseases.

Phthalate Acid Esters (PAEs) in Indoor Dust from Decoration Material Stores: Occurrence, Sources, and Health Risks.

Phthalate acid esters (PAEs) are one of the most widely used plasticizers globally, extensively employed in various decoration materials. However, studies on the impact of these materials on indoor environmental PAE pollution and their effects on human health are limited. In this study, forty dust samples were collected from four types of stores specializing in decoration materials (flooring, furniture boards, wall coverings, and household articles). The levels, sources, exposure doses, and potential health risks of PAEs in dust from decoration material stores were assessed. The total concentrations of Σ9PAE (the sum of nine PAEs) in dust from all decoration-material stores ranged from 46,100 ng/g to 695,000 ng/g, with a median concentration of 146,000 ng/g. DMP, DEP, DBP, and DEHP were identified as the predominant components. Among all stores, furniture board stores exhibited the highest Σ9PAE (159,000 ng/g, median value), while flooring stores exhibited the lowest (95,300 ng/g). Principal component analysis (PCA) showed that decoration materials are important sources of PAEs in the indoor environment. The estimated daily intakes of PAEs through non-dietary dust ingestion and dermal-absorption pathways among staff in various decoration-material stores were 60.0 and 0.470 ng/kg-bw/day (flooring stores), 113 and 0.780 ng/kg-bw/day (furniture board stores), 102 and 0.510 ng/kg-bw/day (wall covering stores), and 114 and 0.710 ng/kg-bw/day (household article stores). Particularly, staff in wall-covering and furniture-board stores exhibited relatively higher exposure doses of DEHP. Risk assessment indicated that although certain PAEs posed potential health risks, the exposure levels for staff in decoration material stores were within acceptable limits. However, staff in wall covering stores exhibited relatively higher risks, necessitating targeted risk-management strategies. This study provides new insights into understanding the risk associated with PAEs in indoor environments.

Ultrafine particles formation from ozonolysis of gas- and particle-phases of cigarette smoke

Cigarette smoke and ozone (O3) are two main pollutants in indoor environments and their mutual reaction can generate substantial detrimental substances having synergistic influences on the environment and human health. The aging process of cigarette smoke in the atmosphere is mainly gone through ozonolysis reaction attracting increasing attention in recent years. Herein, the ozonolysis reaction of cigarette smoke with indoor O3 concentrations has been investigated in a Teflon chamber. The gas- and particle-phases of cigarette smoke are divided and their individual ozonolysis process can generate ultrafine particles (UFPs) with high number concentrations. The chemical compositions of the gas- and particle-phases of cigarette smoke as well as their nascent UFPs are measured and their differences during the ozonolysis have been clearly observed with vacuum ultraviolet (VUV) photoionization mass spectrometry. In particular, several representative key species of cigarette smoke, i.e., the gas-phase furan and 2,5-dimethylfuran and the particle-phase nicotine, as well as their ozonolysis products are definitely identified and play an important role in the nucleation formation of UFPs. Their ozonolysis reaction mechanisms are also discussed. In addition, this work demonstrates that the ozonolysis of the particle-phase of cigarette smoke contributes more UFPs than that of the gas-phase.

Formation of secondary aerosol by 222 nm Far-UVC irradiation on SO2

222 nm UV indoor disinfection using KrCl* excimer lamps has been gaining popularity due to claims of minimal ocular and skin damage from direct irradiation. However, the secondary aerosol formation under irradiation of KrCl* excimer lamps, which could be an inhalation hazard, is less explored. SO2, a well-known precursor of outdoor sulfate aerosol, is also ubiquitous in indoor environments in urban cities in northern China where coal is used for domestic heating and cooking. In this work, we studied secondary aerosol formation by 222 nm irradiation on SO2, using a Go: PAM flow reactor, a scanning mobility particle sizer (SMPS), and a time-of-flight aerosol chemical composition monitor (ToF-ACSM). The formation of sulfate nanoparticles was found much more effective at 222 nm than at 254 nm and under fluorescent lamp (FL) irradiation at the same UV doses and RH, likely due to different SO2 oxidation mechanisms. We have also found that NH3 and cooking volatile organic compounds (CVOC), as other indoor-relevant gases, promoted the formation of secondary aerosols by 222 nm radiation on SO2. Overall, 222 nm disinfection can generate secondary pollutants in indoor environments. Caution should be taken during its indoor applications, especially in areas with high SO2 concentrations such as coal-fueled households.

Design of Environmental Monitoring and Alarm System Based on Microcontroller

With the development of society, the improvement of science and technology, and the continuous optimization of production and life, people's living standards are also constantly improving. Therefore, people are starting to pay more and more attention to the comfort level of indoor environment. Housing is not only a place for family reunion and living, but also an important material guarantee for people's lives. However, with the rampant use of decoration materials and the increasing popularity of daily necessities, the hidden dangers of the living environment have greatly increased. Indoor environmental pollution has become one of the serious killers affecting modern human health, seriously affecting people's production and life. Therefore, it is particularly important to monitor the indoor environment, which not only needs to sensitively detect the concentration of various harmful gases, but also has an alarm function to constantly remind of dangers. The main functions of this design include: Connecting the microcontroller with temperature, humidity, and gas sensors to achieve real-time collection and reading of indoor temperature and humidity values, as well as monitoring gas concentration, and achieving the expected results. The display circuit was designed using LCD. The buzzer alarm function was used to automatically alarm when the gas concentration and temperature/humidity values exceeded the set standard values. When the temperature and humidity exceed the limit, the LCD display can immediately prompt and combine with LED alarm. When the gas concentration exceeds the limit, LED alarm is used.

Mercury accumulation efficiency of different biomonitors in indoor environments: the case study of the Central Italian Herbarium (Florence, Italy)

Biomonitoring studies are often employed to track airborne pollutants both in outdoor and indoor environments. In this study, the mercury (Hg) sorption by three biomonitors, i.e., Pinus nigra bark, Pseudovernia furfuracea lichen, and Hypnum cupressiforme moss, was investigated in controlled (indoor) conditions. In comparison to outdoor environments, controlled conditions offer the opportunity to investigate more in detail the variables (humidity, temperature, pollutants speciation, etc.) that control Hg uptake. The biomonitors were exposed in two distinct periods of the year for 2 and 12 months respectively, in the halls of the Central Italian Herbarium (Natural History Museum of the University of Florence, Italy), which are polluted by Hg, due to past plant sample treatments. The Hg sorption trend was monitored every 3 weeks by recording: (i) the Hg content in the substrata, (ii) gaseous elemental mercury (GEM) concentrations in the exposition halls, (iii) temperature, (iv) humidity, and (v) particulate matter (PM) concentrations. At the end of the experiment, Hg concentrations in the biomonitors range from 1130 ± 201 to 293 ± 45 μg kg−1 (max–min) in barks, from 3470 ± 571 to 648 ± 40 μg kg−1 in lichens, and from 3052 ± 483 to 750 ± 127 μg kg−1 in mosses. All the biomonitors showed the highest Hg accumulation after the first 3 weeks of exposure. Mercury concentrations increased over time showing a continuous accumulation during the experiments. The biomonitors demonstrated different Hg accumulation trends in response to GEM concentrations and to the different climatic conditions (temperature and humidity) of the Herbarium halls. Barks strictly reflected the gaseous Hg pollution, while lichen and moss accumulation was also influenced by the climatic conditions of the indoor environment. Mercury bound to PM seemed to provide a negligible contribution to the biomonitors final uptake.

Pollution status, particle-size distribution and health impacts (people at different ages) of polybrominated diphenyl ethers in bedrooms

Polybrominated diphenyl ethers (PBDEs) are widely found in the environment owing to the widespread use of brominated flame retardants. In recent years, polybrominated diphenyl ethers have attracted increasing attention because of their harmful effects on human health, especially in children, and have been recognized as significant indoor environmental pollutants. In this study, PBDEs were detected in 80 samples of air, dust, and particulate matter from bedrooms in Hangzhou, indicating that PBDE pollutions in bedrooms occur widely. The median concentration of ∑8PBDEs in dust was 8.54 ng/g, whereas in air and particulate matter was 13.60 pg/m3 and 23.94 pg/m3, respectively. BDE-209 was the main congeners in particles and dust. The mass distribution of atmospheric particles in bedrooms showed a bimodal distribution, mainly in the segments of < 1.1 and 3.3 − 4.7 µm. Through the analysis of typical bedroom materials, the specific PBDEs concentration order was as follows: curtain < wallpaper < mattress < socket panel, with median concentrations of 21.90 µg/g, 45.74 µg/g, 46.31 µg/g and 74.85 µg/g, respectively. The possible sources of PBDEs in residential air, dust, particulate matter was mattress, curtains and mattresses, and mattress and curtains, respectively. Infants have the highest daily exposure dose (DED) for ∑5PBDEs in the air and particulate matter phases, while toddles have the highest DED in dust. The HQ（Hazard Quotient）of infants, toddlers, children, teenagers, and adults were 8.58E-05, 1.06E-04, 4.17E-05, 2.53E-05 and 1.09E-05, respectively, indicating that pollution in bedrooms will not negatively impact human health. However, related studies have shown that children are more likely to be exposed to PBDEs than adults. Therefore, for infants and young children with weaker resistance and long-term family environments, PBDEs pollution may harm their health and growth.

Health risk assessment of BTEX compounds (benzene, toluene, ethylbenzene and xylene) in different indoor air using Monte Carlo simulation in zahedan city, Iran

The presence of benzene, toluene, ethylbenzene, and xylene compounds (BTEX) in the breathing air outside and inside buildings is one of the most significant problems related to human health today. This study was performed to determine the concentration of BTEX pollutants in indoor environments. PhoCheck was used to detect the concentration of BTEX compounds. In this study, the concentration (BTEX pollutant) was assessed in four indoor spaces, including restaurants, laundries, hair salons, and photocopying centers. The results showed that the average concentration of all four searched compounds was higher than the recommended limit of the Environmental Protection Agency (EPA). The results of carcinogenic risk assessment by benzene and ethylbenzene compounds show 2153 × 10−4 and 913 × 10−5 respectively. The HQ values for toluene and xylene were 1.397 and 0.505, respectively, indicating that exposure to toluene alone may have adverse effects on human health, while exposure to xylene alone has no adverse effects. The hazard index (HI) for toluene and xylene pollutants was higher than one. An HI value higher than one means that the two contaminants toluene and xylene in the air we breathe may have adverse effects on human health. As a result, the necessary control measures should be taken to prevent the unfavorable effects of these two pollutants.

SiO2/BiOX(X=Br, Cl) nanophotocatalysts chemically loaded on the surface of alkali slag-fly ash cement-based materials for photocatalysis

The application of nanophotocatalysts on the surface of cement-based materials shows excellent purification and self-cleaning ability, which is an important research and development direction to solve the indoor and outdoor environmental pollution problem at present. In this work, a novel and efficient SiO2/BiOX(X = Br, Cl) nanophotocatalytic material was prepared by a simple co-precipitation method and successfully loaded on the surface of alkali slag-fly ash cement-based materials. The SiO2/BiOX(X = Br, Cl) nanophotocatalyst showed excellent photocatalytic performance in the degradation of Rhodamine B (RhB) and formaldehyde (HCHO). The nanophotocatalyst doped with 2 mL tetraethyl orthosilicate (TEOS) was able to completely degrade RhB (20 mL/g) in 50 min, and the removal rate of HCHO could reach 61.80% in 40 min. Meanwhile, the higher specific surface area of SiO2/BiOX(X = Br, Cl) also provided more active sites, giving the cement matrix an excellent ability to adsorb pollutants. Thus, SiO2/BiOX(X = Br, Cl)-cem showed promising data on the degradation of HCHO, with a maximum degradation rate of 51.97% in 40 min, which is beneficial for improving indoor air quality. More importantly, the active SiO2 in SiO2/BiOX(X = Br, Cl) can react with the alkaline components in the cement matrix and promote the generation of gel to form a strong chemical bond between the photocatalytic material and the cement matrix, which effectively prolongs the action time of the photocatalyst on the cement matrix and improves the dense degree of the cement matrix surface. This provides an idea for solving the problem of easy flaking of the photocatalyst caused by the simple coating method.

Improving Indoor Air Quality through Standardization

Human beings experience a large fraction of their exposure to air pollutants in indoor environments. Air pollution is a large environmental health risk, and exposure to ambient air pollution and indoor air pollution contribute equally to the total number of fatalities worldwide. Although legislative authorities have established limit values for ambient outdoor air and stack emissions, there are inconsistent and variable national and regional limit values for gaseous substances and airborne particulate matter in the built environment (schools, homes, healthcare facilities, offices, and other public spaces). This lack of regulation is unsurprising, because indoor spaces are characterized by complex air chemistry, and their construction materials and types of activities vary significantly. The current understanding of indoor pollutants, including short-lived oxidants, degradation of VOCs, particle formation, and particle composition, is incomplete. It is necessary to identify and assess emerging pollutants and their toxicity, and to consider new consumer products and green construction materials and their impact on indoor air quality (IAQ). Learning from IAQ surveys and audit protocols, research methodologies should be regularized for cross-research comparisons. Some indoor air quality guidance and standards have been written, and several more are in development, with the international ISO 16000 series of indoor standards leading the way for improving indoor air data quality. The WHO has established some ambient air limit values which can mostly be translated into indoor limit values. The built environment needs to harmonize energy efficiency, thermal comfort and air quality standards and guidance. In this review, we discuss the next steps for improving international, regional and national standards and guidance, leading to better and more complete indoor air quality regulations.

Green Walls as Mitigation of Urban Air Pollution: A Review of Their Effectiveness

Mitigation of urban air pollution has been constrained by the availability of urban spaces for greening. Green walls offer the prospect of greening spaces and surfaces without requiring large areas. Green walls can largely be divided into green facades where the aboveground parts of plants rooted in soil and pots grow directly on, and living walls holding bags, planter tiles, trays and vessels containing substrates in which plants are grown. Green facades and living walls can be continuous or modular with repeating units that can be assembled for extension. This review aims to present the effectiveness of green walls in removing different types of air pollutants in indoor and outdoor environments. It examined more than 45 peer-reviewed recently published scholarly articles to achieve the aim. It highlights that most of the studies on green walls focus on particulate matter removal and green walls could effectively remove particulate matter though the effectiveness varies with plant types, air humidity, rainfall and its intensity, leaf area index and contact angle, green wall surface coverage ratio, as well as the height of green walls. Increasing the height of green walls and optimizing their distance from roadsides could promote the deposition of particulate matter. Washing off could regenerate plant surfaces for capturing pollutants. Green walls are also effective in removing NO2, O3, SO2 and CO. Indoor active living walls, when properly designed, could have air purifying performance comparable to a HVAC system. The performance of green walls could be optimized through polycultures, selection of plants, surface coverage and height, and air inflow.

Healthy Residential Indoor Air Quality

Healthy indoor environments are important components of sustainable housing. Creating such environments means avoiding health hazards from mold and other allergens, combustion pollutants, volatile organic compounds, radon, lead, and asbestos. Ways of doing so include use of water-managed building foundations, site drainage, adequate ventilation, informed selection of equipment for space conditioning and water heating, material choices, and sub-slab ventilation. Lead and asbestos are concerns in rehabilitating older homes and are addressed through well-established best practices. The purpose of this paper is to examine indoor environmental pollutants, their impacts on human health, and methods to avoid and mitigate exposure. The presence of asthma triggers in homes has become an increasingly serious indoor environmental issue and will be covered in more depth.

Inhalation and deposition of gas–droplet contaminant in the human microenvironment in an industrial building

Gas–droplet contaminants such as HCl gas and hydrochloric droplets are typical pollutants in industrial indoor environments. They are harmful to workers. As the transportation modes of the gas and droplet phases are different, they cause different exposure characteristics for human beings. This study numerically investigated the transport of HCl gas and hydrochloric droplets emitted from a pickling tank to a human microenvironment. Meanwhile, inhalation and deposition of hydrochloric acid gas and hydrochloric acid droplets by humans were also studied, which were influenced by the droplet initial diameter (10–100 μm), air draught (0.1–0.5 m/s) and the distance between the source and the manikin (0.5–1.5 m). The results showed that the cases considering an initial droplet diameter of 50 μm could cause the largest droplet deposition on the manikin, which was influenced by the combination of droplet gravity and plume. The velocity of the air draught could significantly enhance the inhalation of HCl gas and droplet deposition on the manikin when the velocity was ≥ 0.3 m/s. Furthermore, when the distance was increased from 1.0 to 1.5 m, the thermal plume enhanced the inhalation of HCl gas.

Accelerated settling velocity of airborne particulate matter on hairy plant leaves

Phytoremediation has emerged as an ecofriendly technique to reduce hazardous particulate matter (PM) in the air. Although previous studies have conducted statistical analyses to reveal PM removal capabilities of various plant species according to their leaf characteristics, the underlying physical mechanism of PM adsorption of plants remains unclear. Conventional methodologies for measuring PM accumulation usually require long-term field tests and provide limited understanding on PM removal effects of individual leaf traits of various plants. In this study, we propose a novel methodology which can compare the electrostatic interactions between PMs and plant leaves according to their trichome structures by using digital in-line holographic microscopy (DIHM). Surface characteristics of Perilla frutescens and Capsicum annuum leaves are measured to examine electrostatic effects according to the morphological features of trichomes. 3D settling motions of PMs near the microstructures of trichomes of the two plant species are compared in detail. To validate the PM removal effect of the hairy microstructures, a polydimethylsiloxane (PDMS) replica model of a P. frutescens leaf is fabricated to demonstrate accelerated settling velocities of PMs near trichome-like microstructures. The size and electric charge distributions of PMs with irregular shapes are analyzed using DIHM. Numerical simulation of the PM deposition near a trichome-like structure is conducted to verify the empirical results. As a result, the settling velocities of PMs on P. frutescens leaves and a PDMS replica sample are 12.11 ± 1.88% and 34.06 ± 4.19% faster than those on C. annuum leaves and a flat PDMS sample, respectively. These findings indicate that the curved microstructures of hairy trichomes of plant leaves increase the ability to capture PMs by enhancing the electric field intensity just near trichomes. Compared with conventional methods, the proposed methodology can quantitatively evaluate the settling velocity of PMs on various plant leaves according to the morphological structure and density of trichomes within a short period of time. The present research findings would be widely utilized in the selection of suitable air-purifying plants for sustainable removal of harmful air pollutants in urban and indoor environments.

Photocatalytic Degradation of Gaseous Acetone by Photocatalysts with Visible Light and their Potential Applications in Painting

Volatile organic compounds (VOCs) are air pollutants associated with health problem. Paints mixed with photocatalytic (PC) materials are considered to be effective in the removal of VOCs. Therefore, this investigation aimed to produce a novel visible induced photocatalyst component in paint. The synthesized photocatalysts (i.e., Ag/TiO2 and Fe/TiO2) were self-prepared by sol-gel method and further used to produce paints. The effects of the paints on VOC (i.e., acetone) degradation under the irradiation of visible light were tested in a batch PC reactor and an environmental chamber. In order to evaluate the control effect of VOCs using the paint, a simulated test was conducted in a real room. The results of batch experiments showed that the degradation efficiencies of acetone by the paints were lower than that by the related photocatalysts. The paints made of 3% Fe/TiO2 and 1% Ag/TiO2 achieved the highest acetone degradation efficiency of 32.7% and 21.3%, respectively. The degradation test conducted in the environmental chamber indicated that the degradation efficiencies of acetone were 24.9%, 46.2%, and 32.4% for the paints made of TiO2, 3% Fe/TiO2 and 1% Ag/TiO2, respectively. It was evidently provided that the paint made of 3%Fe/TiO2 could effectively degrade organic pollutants in indoor environments.

Estimated daily intake of per- and polyfluoroalkyl substances related to different particle size fractions of house dust.

Indoor environmental pollutants are a threat to human health. In the current study, we analysed 25 per- and polyfluoroalkyl substances (PFASs) in seven different size fraction of house dust including the two relevant for exposure via ingestion and inhalation. The highest PFAS concentration is found in the inhalable particulate fraction which is explained by the increased surface area as the particulate's sizes decrease. The estimated daily intake (EDI) of the individual PFAS and exposure pathways were calculated for children and adults. In addition, the total EDI for PFOA and its precursors was estimated. The polyfluoroalkyl phosphoric acid diesters (diPAP), followed by PFOA and PFHxA fluortelomer, showed the highest concentrations of PFAS analysed. The cumulative EDI of PFAS for children was 3.0ng/kg bw per day, a worst-case scenario, which is 17 times higher than the calculated EDI for adults. For children, ingestion of dust was found to result in 800 times higher PFOA exposure than via inhalation. The contribution from PFOA precursors corresponded to only 1% of the EDI from dust indicating PFOA as the main source of exposure. The EDI's of PFOA and PFOS from dust were lower than the calculated EDI's from food ingestion reported by the Swedish Food Agency. Our data indicate that the EDI for the sum of four PFASs: PFOA, PFNA, PFHxS and PFOS from dust intake alone is close to the established tolerable weakly intake of 4.4ng/kg bw in children, set by European Food Safety Authority (EFSA) in 2020. The combined EDI levels PFOA and PFOS from both dust and food exceeded the EFSA TWI for both children and adults. This study demonstrates that dust is a relevant exposure pathway for PFAS intake and that analysis of relevant particle size fractions is important for evaluation of dust as an exposure pathway.

포스트 코로나 시대의 대학교 주변 원룸형 주택에 대한 실내 공기질 분석 및 위해성 평가

In this study, in order to grasp the current situation of indoor environmental pollution and indoor ventilation in one-room around the university in the post-corona era, we analyzed the experimental data and conducted a questionnaire survey on university students. By analyzing the content, the effects of formaldehyde, dust and other pollution on the human body, which are usually not easily detectable, are digitized and more easily taken into account. Among the experimental results, the concentration of VOC and HCHO, gas pollutants among indoor pollutants, exceeded the recommended criteria of the Ministry of Environment in most studio apartments. Overall, the average CO2 concentration was lower than the Ministry of Environment's maintenance standard (1000ppm), but it was relatively high in summer and winter, and it is believed to be caused by cooling and heating in an enclosed space. The levels of PM2.5 and PM10, particulate pollutants, increased in November and December, and it is believed that ventilation defects due to degradation in external temperature. There was no clear difference between the two types, and there was a very high correlation between PM2.5 and PM10, HCHO and VOC. It was found that temperature was closely correlated with all sources except CO2, and humidity was closely correlated with all sources except PM2.5 and PM10. Health risk assessment was conducted for formaldehyde. The average ECR of studio R2 in May was 3.91E-4, and the ECR figure in September was 3.65E-4, which was very high compared to other residential spaces. The R2 level was calculated as 4 people per 10,000 people in the lifetime risk of cancer of residents, exceeding the allowable risk. R8 also showed higher ECR results than other spaces after R2, especially in October, 2.01E-4, six times higher than R7 measured in October, and 1.87E-4 in July, four times higher than R9.

Real-time monitoring of pollutants in occupied indoor environments: A pilot study of a hospital in China

Indoor air pollution has severe impacts on human health. Few studies have focused on indoor air quality (IAQ), especially air pollution in the hospital, which is sensitive due to its high mobility and multiple carriers. The traditional experiments usually develop in artificial environments, which lack authenticity with limited consideration for indoor occupancy than that in real environments. This study adopts field investigation, from a data-driven perspective aimed to evaluate pollutants in occupied indoor environments, including carbon dioxide (CO2), particulate matter (PM10 and PM2.5) and total volatile organic compounds (TVOCs) in a hospital in China, emphasising their dynamic variation patterns and characteristics under natural ventilation. The results indicated that (1) the concentrations of indoor pollution in areas with high population densities were typically higher than those in outdoor and low-occupancy-level working areas; (2) indoor air pollutants, including PM2.5, PM10, and CO2, were significantly influenced by indoor activities under the same outdoor conditions; (3) TVOCs were different from the other pollutants and exhibited a lower periodicity; that is, the changes in TVOCs concentrations were more likely to be affected by non-fixed interference sources. In the end, suggestions were made for the improvement and management of the hospital's IAQ according to the research results. This study as a comprehensive analysis may provide operational guidelines for managing and improving indoor environments in hospitals in China.

The current status of research on the catalytic oxidation of formaldehyde

ABSTRACT Formaldehyde (HCHO), which is one of the common pollutants in indoor environment and industrial processes, can cause adverse effects on human health. The thermal catalytic oxidation technology is regarded as the most promising approach due to its easy handling and environmental friendliness. This article reviews the current status of the catalytic oxidation of HCHO over noble metal and transition metal oxide catalysts. The general feature and the reaction mechanism of the catalytic oxidation of HCHO are summarized first. Based on the discussion of the reaction mechanism, the influence of some factors (catalyst preparation process, catalyst support, promoter and morphology) on the activity of the catalyst have been addressed. The structure of the catalysts has been elucidated and correlated with the reaction mechanism as well as the catalytic performance. Finally, the perspectives for the catalytic oxidation of HCHO in future research are presented. Hopefully, this review can shed light on the design of more active catalysts for HCHO oxidation to realize their practical application.