Deterioration Of Indoor Air Quality Research Articles

Verification of Ventilation and Aerosol Diffusion Characteristics on COVID-19 Transmission through the Air Occurred at an Ice Arena in Japan

This study is about a COVID-19 outbreak and ventilation measures taken against COVID-19 transmission through the air occurred at an ice arena in Japan. The ice arena has been known to have a deterioration of indoor air quality affected by CO, NO2 and so on, and a total of 172 persons were infected with SARS-CoV-2, including the players and the spectators related to an ice hockey game in 2022. Given the suspected transmission through the air as one of infection routes, the primary objective of this study was to investigate the COVID-19 outbreak to verify the ventilation characteristics and aerosol diffusion characteristics. Additionally, the possibility of COVID-19 transmission through the air and the potentially effective ventilation measures in an ice arena are discussed. It was determined that the virus-containing aerosol was released from a player in the ice rink and accumulated in the cold air spot. After that, it was highly possible that it diffused from the player benches to the spectator seats due to the players’ movements under this unique air-conditioning and ventilation system. Judging from the results of genomic analysis, ventilation characteristics, and aerosol diffusion characteristics, the possibility of COVID-19 transmission through the air cannot be ruled out in an ice arena. The results of ventilation measures implemented in response to this problem confirmed that the integration of a lower-level exhaust fan based on cold air characteristics into the existing ventilation system is a relatively straightforward solution with the potential to be highly effective. While there is an option to refrain from using the ice arena in the event of an increased risk of mass infection during a pandemic, the findings of this study will contribute to an option to facilitate the smooth operation of ice arenas while implementing ventilation measures.

Determining Formaldehyde Phytoremediation Efficacy of Selected Ornamental Plants

In the recent past, deterioration of indoor air quality has become a serious concern due to the increased energy efficiency and reduced air exchange rate inside urban buildings. Volatile organic compounds (VOCs) are a major category of indoor air pollutants that can lead to adverse health outcomes such as headaches, allergies and asthma in those exposed for prolonged periods. Formaldehyde, the VOC used in the present study is a common contaminant of indoor air which originates from particle board, plywood, paper products, certain adhesives, tobacco smoke and other sources. The use of plants for the mitigation of indoor air pollution is viewed as a cost effective and eco-friendly method with untapped potential. The main objective of the present study was to determine the formaldehyde removal efficacy of selected plant species while investigating the mechanisms used by these plants in the removal process. The selected plant species were Zamioculcas zamiifolia, Hedera helix, Dracaena sanderiana and Ficus sp. Plants of the same age were used with three replicates from each species. Phytoremediation potential was assessed by exposing the plants for 24 hours to gaseous formaldehyde (2.0 μL L-1) in air tight chambers made of Plexiglass (an inert material for VOCs) with dimensions of 0.9 m height×0.58 m length×0.55 m width. Formaldehyde removal was measured using GC-MS and the result was expressed as removal percentages. Several leaf anatomical characters (cuticle thickness, epidermal thickness and mesophyll layer thickness), stomatal characters (stomatal density, stomatal index, guard cell length and potential conductance index) and physiological characters (stomatal conductance and photosynthetic rate) were measured to study the possible mechanisms involved in the formaldehyde removal process. The data were subjected to ANOVA and Pearson correlation test. According to the results obtained, Ficus sp. had the highest formaldehyde removal percentage (92.80%) while Hedera helix had the lowest (56.86%). The study further showed that stomatal density and stomatal conductance play a major role in formaldehyde removal by these plants while cuticle and epidermal thickness act as hindrances to this process. This conclusion was further confirmed by Pearson‘s correlation values in correlation analysis. The current study was carried out for 24 hours of exposure and it would be of interest to explore, the long term behavior of the plants through further studies. Overall, the results justify future studies on a cross-section of diverse plant species for formaldehyde removal efficiency to determine species with superior removal efficiencies for a better phytoremediation process. 
 Keywords: Phytoremediation, VOCs, Formaldehyde, GC-MS technology

Factors of Air Quality Reduction in Public and Residential Premises

T is article presents the characteristics of hazardous chemicals that can be found in public and residential premises, considers possible sources of release of hazardous chemicals into the indoor air environment, considers carbon dioxide as an additional factor in the deterioration of indoor air quality.

Operation method for the air purifier and ventilation systems of old school classrooms considering noise

Old schools with low airtightness performance are vulnerable to outdoor fine dust. Air purifier and ventilation systems are typically used to improve indoor air quality. However, due to the noise that these systems generate, some classrooms do not operate these mechanical facilities despite the deterioration of indoor air quality. This study aimed to propose a ventilation operation method for appropriate improvement of indoor air quality through CONTAMW simulation while minimizing students' disturbance from noise from air purifier and ventilation systems. By controlling the volume of air in the air purifier and ventilation system, it is possible to minimize this disturbance in an old school and effectively improve indoor air quality.

School Children Exposure to Low Indoor Air Quality in Classrooms During Covid-19 Pandemic: Results of a Pilot Study

Background: Indoor air quality (IAQ) in classrooms affects children s health and academic performance. The aim of this pilot study was to determine IAQ in elementary schools different in their internal and external characteristics, in settings of COVID-19 epidemics. Methods: IAQ parameters: fine particulate matter (PM2,5) mass concentration, CO2 concentration, temperature and relative humidity were measured in parallel in four elementary schools/classrooms during October (non-heating season) and four months (including holiday in January) of heating season. IAQ parameters were measured in settings of anti-epidemic restrictions (≤13 students in classroom, frequent ventilation). Results: During October, except in one school, PM2,5 concentrations were below the upper recommended value (25μg/m ), but started rising in all schools in the heating season. The highest concentrations of PM2,5 were registered in two schools with closed or shortly opened windows. CO2 concentrations were mostly in the recommended range (up to 1000ppm) except in the school with constantly closed windows and in three schools in February when concentrations were higher. Except in one, the same school, and in January, both temperature and relative humidity were out of the recommended range (24,0 27,0°C in non-heating;20,0 24,0°C in heating season;and 45 55%), with temperature mainly above and relative humidity mainly below it in three schools. The largest deviation in temperature and relative humidity were registered in urban schools. Registered differences may be explained by different internal and external characteristics. Original paper Conclusion: Despite anti-epidemic restrictions, most of the measured IAQ parameters were out of the recommended values in heating season. In addition, further deterioration of IAQ could be expected if all students had been presented in the classroom. Finally, to assure a healthy school environment in heating season, further optimisation of both indoor and outdoor conditions is needed in both pandemic and non-pandemic settings.

Performance evaluation and parameter sensitivity analysis of a membrane-based evaporative cooler with built-in baffles

Evaporative cooling systems have attracted increasing attention for energy-efficient air conditioning applications. A hollow fiber membrane-based direct evaporative cooler (HFM-DEC) is proposed in this study. The selected membrane material can selectively allow only water vapor to penetrate, while preventing the passage of bacteria and fungi, thereby avoiding deterioration of indoor air quality. Compared with the conventional evaporative coolers with counter-flow and cross-flow arrangements, the proposed novel configuration performed better cooling ability by installing baffles in the air flow channel to enhance the air disturbance. The parameter sensitivity analysis was conducted on the HFM-DEC with built-in baffles by employing an experimentally validated numerical model. The orthogonal test method was used to study the influence of nine key parameters of the HFM-DEC on its wet-bulb effectiveness, coefficient of performance, and the cooling capacity. According to the optimized scheme, the HFM-DEC with a relatively optimal configuration was proposed. The cooling performance of this module was investigated under various inlet air conditions. The results showed that if the inlet air velocity was maintained within the range of 0.5–2 m/s, it was capable of achieving an optimal performance with the wet-bulb effectiveness of 70%-95%, the COP of 17–78, and the cooling capacity of 60–106 W, respectively, under diverse weather conditions. Correlations of Nusselt number and Sherwood number were developed by fitting the simulation results. The influence of Reynolds number on air stream characteristics was obtained based on the analysis of the velocity field, temperature field and concentration field of this module under varying operating conditions.

Exhaled Carbon Dioxide as a Physiological Source of Deterioration of Indoor Air Quality in Non-Industrial Environments: Influence of Air Temperature

People are the main reason for the deterioration of indoor air quality (IAQ) due to the continuous physiological metabolism processes in their bodies, including respiration. We present results from an investigation of the influence of indoor air temperature on the concentration of exhaled carbon dioxide (CO2). The investigation was preconditioned by previous findings on the effect of air temperature on human metabolism. However, our literature survey showed a lack of studies on the influence of the indoor air temperature on the exhaled CO2 (or metabolic CO2), which leads to the novelty of our results. Our experiments had two phases: measurement in a university classroom with an installed heating, ventilation, and air-conditioning (HVAC) system during regular classes and measurement in a specially designed small climate chamber, where the time variations of the CO2 concentrations, together with some physiological parameters, were measured. Two indoor air temperatures were set: 23 °C and 27 °C. The results obtained and their respective analyses show the strong effect of the two air temperatures on the CO2 concentration due to exhalation. In the classroom, the CO2 concentration at 27 °C was higher by 6.2% than at 23 °C. In the climate chamber, the CO2 concentration at 27 °C was higher by 9.6% than at 23 °C. Physiological parameters (oxygen saturation pressure, pulse rate, end-tidal CO2, and respiration rate) and their dependence on the air temperature were also measured in the climate chamber, establishing an effect of the temperature on the pulse rate.

Simulation of thermal and humid environment of rural residence envelope inner surface during the plum rains season in Changsha China

The Plum Rains Season (PRS) has the typical characteristics of outdoor air temperature dramatic changes and high air humidity in the hot summer and cold winter region in China. Even if the indoor heat source and moisture production is constant, when the outdoor air temperature rises rapidly during high air humidity PRS, the building envelope temperature heats up much more slower than the indoor air temperature and therefore the wall surface temperature is lower than the indoor air dewpoint which leads to condensation phenomenon, resulting in deterioration of insulation performance, mouldy walls, deterioration of indoor air quality. At present, there is a lack of research on the factors affecting condensation in rural residence during PRS. This paper evaluates the impact of occupants’ habit of window opening modes and building construction parameters on the building envelope surface condensation in Changsha during PRS. Using Designer'Simulation Toolkit (DeST) simulated and analysed the impact of key parameters such as window-to-wall ratio, exterior wall reflectivity, window opening mode (open/close), and external wall insulation on the building indoor thermal and humid environment. The condensation risk X is proposed to evaluate the condensation possibility on the building envelope's inner surface. The results show that from the perspective of anti-condensation: The rural residential building in Changsha should balance the window-wall ratio against better natural lighting; Keeping windows closed during PRS can effectively alleviate the condensation problem while the insulation in the external wall layer could aggravate the condensation.

The Role of Environmental Risk Factors on the Development of Childhood Allergic Rhinitis.

Environmental factors play an important role in the development and exacerbation of allergic rhinitis (AR) in childhood. Indoor air pollution, such as house dust mites and secondhand smoke, can significantly increase the onset of AR, while pet dander may affect the exacerbation of AR symptoms in children. Furthermore, traffic related air pollution and pollen are outdoor air pollutants that can affect immune competency and airway responsiveness, increasing the risk of AR in children. Climate change has increased AR in children, as growth patterns of allergenic species have changed, resulting in longer pollen seasons. More extreme and frequent weather events also contribute to the deterioration of indoor air quality due to climate change. Additionally, viruses provoke respiratory tract infections, worsening the symptoms of AR, while viral infections alter the immune system. Although viruses and pollution influence development and exacerbation of AR, a variety of treatment and prevention options are available for AR patients. The protective influence of vegetation (greenness) is heavily associated with air pollution mitigation, relieving AR exacerbations, while the use of air filters can reduce allergic triggers. Oral antihistamines and intranasal corticosteroids are common pharmacotherapy for AR symptoms. In this review, we discuss the environmental risk factors for AR and summarize treatment strategies for preventing and managing AR in children.

Window operation behaviour and indoor air quality during lockdown: A monitoring-based simulation-assisted study in London

The Covid-19 outbreak has resulted in new patterns of home occupancy, the implications of which for indoor air quality (IAQ) and energy use are not well-known. In this context, the present study investigates 8 flats in London to uncover if during a lockdown, (a) IAQ in the monitored flats deteriorated, (b) the patterns of window operation by occupants changed, and (c) more effective ventilation patterns could enhance IAQ without significant increases in heating energy demand. To this end, one-year’s worth of monitored data on indoor and outdoor environment along with occupant use of windows has been used to analyse the impact of lockdown on IAQ and infer probabilistic models of window operation behaviour. Moreover, using on-site CO2data, monitored occupancy and operation of windows, the team has calibrated a thermal performance model of one of the flats to investigate the implications of alternative ventilation strategies. The results suggest that despite the extended occupancy during lockdown, occupants relied less on natural ventilation, which led to an increase of median CO2concentration by up to 300 ppm. However, simple natural ventilation patterns or use of mechanical ventilation with heat recovery proves to be very effective to maintain acceptable IAQ.Practical application: This study provides evidence on the deterioration of indoor air quality resulting from homeworking during imposed lockdowns. It also tests and recommends specific ventilation strategies to maintain acceptable indoor air quality at home despite the extended occupancy hours.

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.

Chemistry of Indoor Pollutants and Their Impacts on Human Health

Indoor air pollution refers to the deterioration of indoor air quality by harmful chemicals and other products, which can be up to 10 times worse than the outdoor air pollution. Almost 90% of the modern human time is spent indoors. In India, out of 0.2 billion people using fuel for cooking; 49% use firewood; 8.9% cow dung cake; 1.5% coal, lignite, or charcoal; 2.9% kerosene; 28.6% liquefied petroleum gas (LPG); 0.1% electricity; 0.4% biogas; and 0.5% any other means. The negative consequences of indoor air pollution result in around 2 million premature deaths every year, with 44% are due to pneumonia, 54% from chronic obstructive pulmonary disease (COPD), and 2% from lung cancer. The so-called "natural" or "ecologic" goods are not inherently free of adverse health effects. Certain other constituents such as terpenoids and linseed oil may be chemically reactive than those from non-ecologic products. Secondary emissions from these products may present a greater risk to human health than those compounds which are substitutes for their precursors.

A numerical investigation of the potential effects of e-cigarette smoking on local tissue dosimetry and the deterioration of indoor air quality.

Electronic (e)-cigarette smoking is considered to be less harmful than traditional tobacco smoking because of the lack of a combustion process. However, e-cigarettes have the potential to release harmful chemicals depending on the constituents of the vapor. To date, there has been significant evidence on the adverse health effects of e-cigarette usage. However, what is less known are the impacts of the chemicals contained in exhaled air from an e-cigarette smoker on indoor air quality, the second-hand passive smoking of residents, and the toxicity of the exhaled air. In this study, we develop a comprehensive numerical model and computer-simulated person to investigate the potential effects of e-cigarette smoking on local tissue dosimetry and the deterioration of indoor air quality. We also conducted demonstrative numerical analyses for first-hand and second-hand e-cigarette smoking in an indoor environment. To investigate local tissue dosimetry, we used newly developed physiologically based pharmacokinetic/toxicokinetic models that reproduce inhalation exposure by way of the respiratory tract and dermal exposure through the human skin surface. These models were integrated into the computer-simulated person. Our numerical simulation results quantitatively demonstrated the potential impacts of e-cigarette smoking in enclosed spaces on indoor air quality.

Problem of radon exposure in energy-efficient buildings: a review

The paper presents an overview of the international scientific and technical publications on a problem of radon accumulation in new energy efficient buildings and in houses reconstructed according to requirements of energy saving. Energy efficiency is an important requirement of the environmentally sustainable development. Housing and communal services have significant potential for energy saving. In Russia, the construction of highest energy efficiency classes buildings occurs at an accelerated rate and reached 75% of all multiapartment houses built in 2017. The applying of modern technologies that reduce heat loss is accompanied by a decrease in the air exchange rate, which leads to deterioration of indoor air quality, in particular, the accumulation of radon. In the international literature, there are examples of the several times growth of radon concentration after the reconstruction of the building, the average radon concentration in retrofitted buildings increased by 22–120%. In new houses built to meet energy saving requirements, there can also be a significant increase in radon concentration compared to low-energy efficiency classes houses. Excess of sanitary and hygienic norms was found in some countries, including Russia. Radon exposure of dwellers of energy-efficient buildings is largely determined by the living habits. Based on the review data, it can be assumed that the average level of Russian population exposure to radon can increase under conditions of intensive construction of energy-efficient buildings.

Real-Time Sensor Response Characteristics of 3 Commercial Metal Oxide Sensors for Detection of BTEX and Chlorinated Aliphatic Hydrocarbon Organic Vapors

The objective of this study was to examine the sensor response characteristics of three commercial Internet of Things (IoT) compatible metal oxide (MOx) sensors in preparation for the development of field-scale sensor networks for the real-time monitoring of volatile organic compounds (VOCs) in indoor environments located in proximity to brownfield sites. Currently, there is limited examination of such sensor responses to relevant mixtures of target VOCs, such as the common petrochemicals benzene, toluene, ethylbenzene, and xylene (BTEX), as well as chlorinated aliphatic hydrocarbon (CAH) contaminants such as tetrachloroethylene (PCE) and trichloroethylene (TCE) which are frequently associated with deterioration of indoor air quality. To address this, a study of three commercial metal oxide (MOx) sensors (SGP30, BME680, and CCS811) was undertaken to examine the sensor response characteristics of individual components as well as mixtures of each of the target BTEX and CAH chemicals over relevant indoor air concentrations within the operating range of the MOx sensors (0–6000 ppb). Our investigation revealed similar response patterns to those previously reported for the thick film MOx sensor to most individual target VOCs, however, response trends for mixtures were more difficult to discern. In general, the MOx sensors we examined demonstrated similar magnitude responses to the CAHs as BTEX compounds indicating reliable detection of CAHs.

Heavy metal characteristics and health risk assessment of PM2.5 in three residential homes during winter in Nanjing, China

Both indoor PM2.5 concentrations and its chemical compositions are of great concern to human health. This study was conducted to characterize PM2.5 in three residential homes with different HVAC-filter (HVAC: Heating, Ventilating and Air-Conditioning) scenarios and one outdoor environment in terms of mass concentration, heavy metal composition (Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, Hg and Pb), enrichment factors (EFs) and health risk assessment. The results verified that the utilization of HVAC-filter system helped to improve indoor air quality significantly with the mean reductions of mass concentration, heavy metal contents and related health risks of indoor PM2.5–22.1%, 29.1%, and 48.0% of the atmospheric PM2.5 respectively. However, the EFs in the home with HVAC-filter system were the highest among the tested indoor and outdoor air PM2.5 which reminded the potential pollution related to stainless ventilation ducts and particle characteristics (smaller than 2.5 μm). No evident contributions of the independent household floor heating facility were found to the improvement or the deterioration of indoor air quality from the comparative analysis (p > 0.05). Fe, Zn, Ni, and Mn were the main constituents of the metal elements and accounted for more than 80% of the total elements while Cd was the most enriched metal. Smelting furnaces and coal combustion were the main sources of Cr, Ni and As. Health risk assessment indicated that carcinogenic risks of selected metals in all tested homes (1.22 × 10−6 ∼ 3.32 × 10−4) were unacceptable while non-carcinogenic risks were within the safe range.

Governance in Occupational Safety and Health in the Aspect of Indoor Air Quality in Malaysia

Occupational safety and health are a field that is often attracted by various parties and organizations and is a modern social movement. The issue of the deterioration of indoor air quality in the work environment is one of the environmental issues. However, when discussing the issue of indoor air quality in terms of occupational safety and health in Malaysia, most of the studies conducted were more focused on the aftermath of indoor air quality and steps its escort to ensure internal air quality problems in the work environment are more temporary. The implementation of governance in occupational safety and health in the aspects of indoor air quality in Malaysia is divided into two, through legal and non-legal methods. Based on the basic beliefs of sustainability governance there are two main approaches namely holistic approach and reductionism. Thus, this study discusses whether the implementation of governance in occupational safety and health governance in the aspects of indoor air quality is influenced by one or a combination of holistic approaches and reductionism based on the analysis of relevant documents. The findings show that each approach has its own payoff and importance in ensuring the implementation of governance occupational safety and health with the involvement of various and structured stakeholders.

Fundamental Study of Hexadecane Removal by Atmospheric Microplasma

In recent years, the deterioration of indoor air quality (IAQ) became a big concern. Because indoors is the place where we spend most of our life, an IAQ is an important factor to be considered for comfortable and healthy living. In this study, we evaluated the products and decomposition process of hexadecane in small and large capacity spaces by using microplasma electrode. In the case of hexadecane removal, both small and large capacity microplasma process could reduce hexadecane by 83% and 89%, respectively. In the process, we found various hydrocarbons such as 1-hexene (C6H12), 1-heptene (C7H14), and 1-octene (C8H 16) as intermediate products. CO2 and N2O were also confirmed as final products of the microplasma treatment process.

Indoor air quality and its effects on humans—A review of challenges and developments in the last 30 years

A reflective approach is adopted in analyzing the reviews on the impact of indoor air quality on humans over the last 30 years (1986–2016). The major findings reiterate the concerns of indoor air pollution (IAP) and provide a deeper understanding of how contaminants contribute to, and interact to accentuate the adverse effects on humans. Issues which have emerged and increased in importance are indoor chemistry, airborne infection, and the impact on performance. Societal trends of rising affluence of the middle class, increased population density in cities, introduction of new synthetic materials, reliance on childcare facilities have led to greater intensity of exposure to IAP. Responses to climate change, energy conservation and singular strategies to manage the complex challenge of IAP have not been effective in alleviating the deterioration of indoor air quality. Innovations in air distribution, air cleaning, modularization of indoor environmental devices/systems, and leveraging on smart technologies and sensing systems which incorporate algorithms that optimizes indoor air quality with conventional performance indicators are important advancements towards a holistic solution. User engagement, both as a sensor and indicator of preferences, when integrated with such innovations, may usher in the next important paradigm towards achieving acceptable indoor environmental quality beyond the current definitions of acceptability from population-based criteria to one that embraces the individual on an as-needed, when-needed and as-preferred basis.

Use of the Buffering Capacity of the Building Envelope for the Reduction of the Rate of Air Exchange

This work addresses the use of humidity controlled ventilation with high buffering capacity building envelope. The humidity controlled ventilation rate is associated to the level of moisture in rooms. This paper fits into the idea of reducing the building energy consumption by reducing the duration of air ventilation rate which is usually quite high. This solution is not without consequences on building because it presents a risk of deterioration of indoor air quality (e.g. non evacuation of VOC) and apparition of mold. This paper aims to enhance water inertia of building walls in order to reduce the ventilation rate and study the risk associated with moisture excess. It is achieved for different scenarios of in-house production of vapor which can be met in reality and for different cases.