Improve Indoor Air Quality Research Articles

Emissions of Semi-Volatile Organic Compounds from Architectural Coatings and Polyvinyl Chloride Floorings: Microchamber Method.

Semi-volatile organic compounds (SVOCs) are modern chemical substances that are present in large quantities in indoor environments. Understanding the emission of SVOCs from building materials is essential to identify the main sources of indoor SVOCs and to improve indoor air quality. In this study, a reference method employing custom-designed microchambers (630 mL) was optimized by improving the structure of the gas path and adding polytetrafluoroethylene inner coating to the chamber. After optimization, the recoveries of the microchamber method were significantly improved (75.4-96.7%), and the background in the microchamber was greatly reduced (<0.02 μg/h). By using the microchamber method, 33 SVOCs (including two alkanes, one aromatic, one nitrogen compound, and twenty-nine oxygenated compounds) and 32 SVOCs (including seven alkanes, eight aromatics, and seventeen oxygenated compounds) were detected in the emissions of the architectural coating and the PVC flooring samples, respectively. The area-specific emission rates (SERa) of total SVOCs emitted from architectural coatings and PVC floorings were in the range of 4.09-1309 μg/m2/h) (median: 10.3 μg/m2/h) and 0.508-345 μg/m2/h (median: 11.9 μg/m2/h), respectively. Propanoic acid had the highest SERa (3143 μg/m2/h) in architectural coatings, while methylbenzene (345 μg/m2/h), 2-methylnaphthalene (65.2 μg/m2/h), and naphthalene (60.3 μg/m2/h) were main SVOCs emitted from PVC floorings. Meanwhile, the average second-stage (adsorbed phase) emission mass of the total SVOCs accounts for 66.3% and 47.3% in architectural coatings and PVC floorings, respectively, suggesting that the SVOCs emitted from building materials have a strong tendency to be absorbed on the surface of the room, e.g., the interior wall, the desk or even the skin.

Development of air purifying curtain using activated charcoal embedded multilayer fabric for effective indoor air filtration

Air pollution poses a significant threat to global health, necessitating effective solutions to mitigate its impact. In this study, we propose an innovative approach to combat indoor air pollution through the development of a multilayer fabric-based air purifying curtain. The curtain comprises inner and outer layers of cotton fabric sandwiched around a middle layer of activated charcoal-treated polyester and cotton blend (PC blend) fabric. Fabrication involved a pad-dry-cure process with activated charcoal particles applied to the fabric surface. To test the efficacy of the developed fabric in filtering hazardous substances such as particulate matter 2.5 (PM2.5), particulate matter 10 (PM10), and total volatile organic compounds (TVOCs), filter quality testing equipment is being designed and fabricated. Comparative analysis with a market-available air purifying curtain (MAPC) revealed comparable air permeability and filtration efficiency for PM2.5, PM10, and TVOCs. Notably, the developed air purifying curtain exhibited a lower contact angle (86°) than MAPC (117°), indicating a hydrophilic nature contributing to enhanced filtration. Our findings suggest that the proposed curtain offers a sustainable and effective solution for indoor air quality improvement.

An annual result of outdoor and indoor PM 2.5 analysis in two different building types in Ulaanbaatar, Mongolia.

Air pollution has been a significant environmental and public health concern in Ulaanbaatar, the capital city of Mongolia, for many years. The city experiences severe air pollution, particularly during the winter months. This study investigated the annual trends of outdoor and indoor PM2.5 concentrations at two neighboring sites in Ulaanbaatar: an office and a household, using low-cost sensors. Both locations exhibited similar fluctuations in outdoor PM2.5 concentrations over time, with ambient PM2.5 levels beginning to rise in October and declining in April. During the mid-term of the heating season (November to February), hourly averaged PM2.5 concentrations were exceptionally high, with peak pollution events exceeding ~ 1000µg/m3. Notably, PM2.5 concentrations were elevated during this heating season period. Time-activity patterns showed a decrease in PM2.5 concentrations during the periods of 06:00-08:00 and 14:00-18:00. Furthermore, the study found that the indoor environment could remain safe when windows were well-sealed, even under severe outdoor pollution conditions. Overall, this study provided accurate insights into the annual patterns of PM2.5 concentrations and demonstrated their fluctuations during the heating season when pollution levels were particularly high. The findings offer valuable recommendations for individuals to consider when going outside and for taking actions to improve indoor air quality in Ulaanbaatar.

Environmental monitoring system design based on STM32 platform

This study addresses the current societal demand for environmental monitoring by designing an environmental monitoring system based on the STM32 platform. This system assesses and monitors environmental conditions in real-time by tracking parameters such as CO, PM2.5, temperature, humidity, and light intensity. It holds significant value in preventing air pollution and improving indoor air quality. The system employs four types of sensors: the DHT11 digital temperature and humidity sensor, the BH1750FV light sensor, the GP2Y1010AUOF optical dust sensor, and the MQ-7 CO sensor to collect environmental data, which is then processed by the STM32F103C8T6 controller. This system is characterized by its real-time capabilities, high precision, and low power consumption, making it highly practical and valuable for widespread application. The paper provides a detailed discussion of sensor selection, measurement algorithms, and system design and implementation, offering valuable insights for research and applications in related fields.

Implementation of an IoT architecture for promoting healthy air quality in 84 homes of families with children

IoT systems incorporating low-cost air quality sensors (LCS) have emerged as valuable tools for empowering citizens to take action to improve indoor air quality (IAQ). This work aimed to assess the effectiveness of a newly developed IoT system in promoting behavioural changes and improving IAQ in 84 homes of families with children. To accomplish this aim, a modular IoT architecture using calibrated LCS was developed to collect real-time data on CO2, temperature, relative humidity and particulate matter (PM2.5 and PM10) during a randomised cross-over trial (November 16, 2022–January 24, 2023). The intervention under study consisted of providing access to real-time IAQ data to participants and alerting them via a smartphone app when CO2, PM2.5, and/or PM10 concentrations were higher than the recommended limits. The findings showed that LCS readings were strongly correlated with those obtained from reference equipment. Nevertheless, long-term assessments revealed a signal degradation effect for the readings obtained from the LCS PM sensor. The comparison of IAQ data from control and intervention periods showed a significant alleviation of CO2 concentrations (mean reduction of 10.3 % in 52 out of 84 participant homes). Notably, about 70 % of participants recognized that data presented through the app motivated them to take valuable actions to enhance IAQ. Overall, this study constitutes a step forward to provide valuable field evidence on the strengths and limitations of using IoT systems based on LCS to empower citizens on the factors that may influence exposure to air pollution at home.

How do occupants experience the onset and triggering of building-related symptoms in damp Australian housing? An inductive-deductive content analysis

In recent years, occupants’ time spent in dwellings has increased concurrently with an increase in the duration and intensity of extreme weather events and the worsening of housing conditions. Indoor dampness and or mould (D/M) are risk factors for building-related symptoms (BRS), yet little is known about how symptoms start, thus hindering where to focus indoor air quality measurements and improvements in occupant safety. This study describes perceived symptom initiators, triggers and coinciding factors that explain what and how symptoms occurred from the perspectives of occupants living with indoor D/M. This study uses an inductive/deductive qualitative analysis, with purposive sampling (n = 154) from data collected via an online survey. Deductive content analysis utilises a framework driven by the Determinants of Health (DoH). Themes that emerged from the inductive analysis include: 1) when occupants or others interact with D/M; 2) when indoor D/M conditions change; and 3) a home full of D/M problems. From the deductive analysis, perceived exposure relating to D/M conditions differed between the initial onset of symptoms and the later triggering of symptoms. Additional coinciding factors relating to climate, socioeconomic, policy and individual factors along with a lack of knowledge, attitudes and beliefs, emerged. This study highlights the need to raise occupant awareness, enhance housing and occupancy regulations, and introduce safe work practices to address the lack of health awareness and health significance regarding indoor D/M housing conditions. It also outlines the need for targeted research measuring bioaerosol exposure related to actions, proximity-based exposure, and wet and repeatedly wet conditions.

Investigating the impact of a window air conditioner with H-14 HEPA filter on lessening SARS-COV-2 aerosols

This research breaks new ground by proposing a unique solution to combat SARS-COV-2 aerosols: modifying a readily available window air conditioner’s indoor blower to accommodate a HEPA (high-efficiency particulate air) filter. While traditional public health measures like lockdowns and mask-wearing remain crucial, this study explores an innovative engineering approach to air purification within homes and offices. The widespread impact of COVID-19 across various sectors—agriculture, manufacturing, finance, and more—necessitates exploring diverse solutions. Current efforts to utilize HEPA filters in HVAC systems face limitations. These filters, while highly effective at capturing airborne particles, increasingly impede airflow and require substantial pressure, posing challenges for standard HVAC systems to maintain efficient operation. This study addresses this critical gap by proposing a targeted modification to a specific window air conditioner (AC) model (GJC07AF-K3RNB9D) to incorporate an H-14 HEPA filter. Utilizing cutting-edge design tool (CF-TURBO) and advanced simulation software (STARCCM +), the research will provide a new blower specifically optimized for this application. This virtual testing will meticulously evaluate the modified system’s performance, ensure optimal airflow, predict noise levels, and identify any potential design flaws before implementing the modification in a physical prototype. The success of this study could pave the way for the development of increasingly efficient and accessible HEPA-based air purification solutions for everyday use, particularly in areas with limited resources. Furthermore, this research can be a valuable foundation for future work aimed to increasingly improve indoor air quality (IAQ).

Assessment of Perceived Indoor Air Quality in the Classrooms of Slovenian Primary Schools and Its Association with Indoor Air Quality Factors, for the Design of Public Health Interventions

From a public health perspective, it is necessary to improve indoor air quality (IAQ) in schools. This study aims to assess the state of perceived IAQ in Slovenian school classrooms and its association with the selected IAQ factors to improve the understanding of perceived IAQ for designing public health interventions aimed to improve IAQ in schools. A national cross-sectional study was performed in all 454 Slovenian primary schools in the school year 2019/2020. The questionnaires were filled out by the 3rd-grade teachers with the support of the caretakers. Teachers rated the IAQ in the classroom as the worst in winter. We found that the teachers’ perceived IAQ in the classroom is statistically significantly associated with the micro location of the school and some of the IAQ factors. Poor IAQ is associated with reduced manual airing of classrooms due to the thermal comfort of the occupants. Interventions should be aimed at improving occupants’ adaptive behaviors to increase the frequency of natural ventilation in classrooms.

Ventilation performance of induction displacement units in indoor spaces within cold regions

Efficient ventilation systems play a crucial role in reducing occupants' exposure to indoor contaminants, including particles potentially carrying viruses like SARS-CoV-2. Displacement ventilation systems have demonstrated their effectiveness in improving indoor air quality during cooling modes. However, traditional displacement ventilation systems often struggle to achieve satisfactory distribution of contaminant concentrations during heating modes. To address this issue, this study focused on enhancing the ventilation performance of a dual-coil displacement-induction unit. Through a combination of experimental measurements and computational fluid dynamic (CFD) techniques, the study examined airflow and contaminant concentration distributions in an environmental chamber conditioned by these units. The results demonstrated good agreement between measured and simulated data, validating the CFD model. Further evaluation in a 25-occupant classroom under cold outdoor conditions showed that the dual-coil unit could achieve satisfactory ventilation performance in heating modes with proper design, comparable to traditional displacement ventilation in cooling modes. Additionally, the unit's versatility allows it to accommodate a wide range of air conditioning applications, from heating to cooling, making it a promising solution for displacement ventilation in various environments.

Relative Health Risk Reduction from an Advanced Multi-Modal Air Purification System: Evaluation in a Post-Surgical Healthcare Setting.

Advanced air treatment systems have the potential to reduce airborne infection risk, improve indoor air quality (IAQ) and reduce energy consumption, but few studies reported practical implementation and performance. PlasmaShield®, an advanced multi-modal HVAC-integrated system, was directly compared with a standard MERV-13 system in a post-surgical paediatric healthcare setting. The evaluation entailed monitoring of multi-size airborne particles, bioaerosols and key IAQ parameters. Measurements were taken for outside air, supply air and air in the occupied space for 3 days prior to, and after, the installation of the PlasmaShield system. Compared with the existing arrangement, very significant reductions in particle number concentrations were observed in the occupied space, especially with virus-like submicron particles. Significant reductions in airborne culturable bacteria and fungi were observed in the supply air, with more modest reductions in the occupied space. In the case of virus-like particles, there was an eight-fold improvement in equivalent clean air, suggesting a five-fold infection risk reduction for long-range exposure. The data suggest multiple benefits of airborne particle and bioaerosol reduction, with applications beyond healthcare. Long-term studies are recommended to confirm the combined IAQ, health and energy benefits.

Endophyte-assisted non-host plant Tillandsia brachycaulos enhance indoor formaldehyde removal

This study investigated the use of endophyte-assisted Tillandsia brachycaulos to enhance formaldehyde removal in indoor environments. A formaldehyde-degrading endophyte from the root of Epipremnum aureum, Pseudomonas plecoglossicida, was identified and used for inoculation. Among the inoculation methods, spraying proved to be the most effective, resulting in a significant 35 % increase in formaldehyde removal after 36 hours. The results of the light exposure experiment (3000 Lux) demonstrate that an increase in light intensity reduces the efficiency of the Tillandsia brachycaulos-microbial system in degrading formaldehyde. In a 15-day formaldehyde fumigation experiment at 2 ppm in a normal indoor environment, the inoculated Tillandsia brachycaulos exhibited removal efficiency ranging from 42.53 % to 66.13 %, while the uninoculated declined from 31.62 % to 3.17 %. The Pseudomonas plecoglossicida (referred to as PP-1) became the predominant bacteria within the Tillandsia brachycaulos after fumigation. Moreover, the endophytic inoculation effectively increased the resistance and tolerance of Tillandsia brachycaulos to formaldehyde, as evidenced by lower levels of hydroxyl radical, malondialdehyde (MDA), free protein, and peroxidase activity (POD), as well as higher chlorophyll content compared to uninoculated Tillandsia brachycaulos. These findings indicate that the combination of endophytic bacteria and Tillandsia brachycaulos has significant potential for improving indoor air quality.

Heat recovery analysis of a fixed plate energy recovery ventilator

As building becomes more leak-tight, air refreshment to improve indoor air quality is needed for healthy living standards. In the quest to ensure comfortable indoor climatic conditions, energy recovery ventilators (ERV) are used to provide air refreshment and thermal comfort. In this study, a fixed plate air-to-air ERV was analysed to determine its effectivity in terms of energy recovery during air refreshment. A customized test bench was built and used to acquire the instantaneous surface temperatures of the heat exchanger plates contained in the ERV during air refreshment. Also, a numerical model of the ERV was developed and validated by comparing its output from simulation with experiment results under the same conditions. The model consisted of a single heat exchanger plate and the air across the plate surface. To capture the effect of heat transfer between the air and the heat exchanger plate in 3D, the model was discretized into numerous cells. From the experiment and simulation results, the air-to-air ERVs were more effective in recovering thermal energy at low flow velocity than at high flow velocity. At lower flow velocity, it will take a longer time duration before any significant impact is made on the thermal conditions of the building, comparatively. The prediction of the model was within acceptable margins and could be used to provide insight on the ERVs performance improvement.

Indoor Air Quality Assessments in 10 Long-Term Care Facilities during the COVID-19 Pandemic, California, 2021–2023

ObjectivesThis study aimed to assess indoor air quality (IAQ) in long-term care facilities (LTCFs) in California during the COVID-19 pandemic and evaluate their implementation of IAQ best practices described by public health authorities to control respiratory pathogen transmission via inhalation. DesignThis observational study conducted IAQ assessments in a convenience sample of LTCFs to gather qualitative data on the implementation of IAQ best practices. The design included 5 pilot visits to develop a standardized method of data collection and then systematic data collection at 10 facilities. Setting and ParticipantsThe study focused on 10 LTCFs across California, chosen from facilities that responded to flyers advertising free IAQ assessments. Some of the facilities had previously experienced COVID-19 outbreaks affecting residents and staff. MethodsState health department industrial hygienists performed site visits to collect data on each facility's heating, ventilation, and air-conditioning (HVAC) system operation, outdoor air introduction, recirculated air filtration, use of portable air cleaners, and directional airflow in isolation areas to evaluate implementation of IAQ best practices in each of these areas. Qualitative data were obtained through visual inspections and interviews with maintenance personnel. ResultsFindings indicated suboptimal implementation of IAQ best practices across the assessed facilities: no facility operated HVAC systems continuously, 40% had all outdoor air dampers open, 20% used MERV-13 or higher rated filters, 20% used portable air cleaners, and 20% performed directional airflow assessment and management for isolating COVID-19 cases. Conclusions and ImplicationsMost LTCFs assessed were not adhering to IAQ best practices, highlighting a significant opportunity for improvement. IAQ best practices described in this study are achievable with existing systems and are critical for reducing virus transmission through the air in LTCFs. The findings underscore the need for more systematic assessments and improvements in IAQ within LTCFs to protect staff and residents.

Greening the Gray: Determining Plant Preferences for Indoor Fitness Gyms in the Philippines

Abstract Biophilia is known as the innate connection people have with nature and how green spaces can positively affect basic cognition, mood and health. Mostly applied in urban areas where outdoor green spaces are scarce, designed facilities that incorporate this concept have been observed to be more beneficial to users. Interestingly, one indoor space visited by urban dwellers that have yet to be studied in terms of biophilic design application is fitness gyms. To determine gym members’ preference of planting materials if these were placed in gyms, surveys were distributed online over two weeks. 239 participants composed of actual and potential gym members selected appropriate plants as detailed in the surveys. Site planting considerations or constraints were also identified if these were used indoors. Additionally, their familiarity with biophilia and its advantages were investigated. After the responses were analysed, participants selected Dracaena fragrans, Spathiphyllum wallisii and Epipremnum aureum as top choices of plants for a gym with major considerations on plants’ aesthetic qualities, ecological and psychological benefits, and maintenance. Moreover, more than 50 percent respondents were at least slightly familiar with biophilia. They believed that having plants can improve indoor air quality, make the interiors more aesthetically pleasing and can enhance mood. As per results, it can be said that the respondents supported the idea of designing indoor fitness gyms as biophilic environments although its level of familiarity needs to be increased. This is where professionals come in, by designing facilities such as fitness gyms with plants to optimize biophilia’s benefits.

Multi-objectives occupant-centric control of thermostats and natural ventilation systems in cold climate conditions using real-time occupant-related information

Recently, Occupant-Centric Controls (OCCs) have attracted great attention. Many studies have applied OCCs to mechanical ventilation systems, while natural ventilation systems have gathered much less attention. The natural ventilation effect, driven by opening windows or vents, can be effective in improving indoor air quality, however, result in a leakage of interior heating energy in winter in cold climates. Therefore, the controls of thermostats and natural ventilation systems shall be designed well so that satisfying levels of thermal comfort, air quality and energy conservation can be simultaneously guaranteed. This study proposes an OCC and applies it to thermostats and natural ventilation systems for indoor thermal comfort, air quality and heating energy management. The strategy comprises three controllers: occupancy-based on-off controller, controller of setpoint of indoor air temperature and window openness controller. First, real-time profiles of heat gains from occupants and window openness were collected by employing vision-based detection. Second, a parametric building simulation study was conducted, and then simulation data were generated to develop predictive shallow artificial neural networks for forecasting the indoor conditions and energy performance of the investigated room. Third, the performance of the proposed strategy was examined. Compared to the baselines, the control could offer a decrease in building heating loads by between 43.4% and 63.8 % and an improvement of predicted mean vote levels by 0.36–0.37. The proposed OCC could also maintain indoor CO2 concentrations below 1000 ppm for about 91 % of the studied time, while 84.2 % of the time with several peaks over 3000 ppm in the baseline cases.

Improved Office Air Quality: Boost to Employee Productivity

Indoor air quality (IAQ) in office environments is a critical factor influencing employee health, well-being, and productivity. This paper explores the correlation between improved indoor air quality and enhanced employee productivity. We review various IAQ enhancement strategies, including ventilation, air purification, and the use of green plants. Several case studies are analyzed to demonstrate the practical application and benefits of these strategies. The paper concludes with recommendations for businesses seeking to optimize their indoor environments for better health and productivity outcomes. Keywords Indoor Air Quality, Health and Air quality, employee wellness and indoor air quality, employee productivity and air quality, role of Air quality on productivity of professionals, IAQ, HAVC, Air purification, productivity and air quality

ANALYSIS OF ENGINEERING ECONOMICS OF THE NEW ERA COMPARED WITH THE CONVENTIONAL MATERIALS USED IN HVAC DUCT APPLICATION

Selecting suitable materials for air ductwork is essential to ensure efficient airflow distribution and reduce economic costs, as it directly impacts an air conditioning system’s overall performance and functionality. The PVC-coated polyester canvas and foam materials have revolutionized the construction of air ductwork, offering numerous benefits and advantages over conventional materials. For instance, these materials have been successfully used in the construction of air ducts for large commercial buildings, resulting in significant energy savings and improved indoor air quality. Using these new-era materials has design flexibility, durability, energy efficiency, and cost-effectiveness. This research has provided a comprehensive analysis of the economic cost of the new era of air ductwork compared with conventional air ductwork in Thailand, and the thorough assessment of total service life costs has improved on the financial implications of adopting this new technology. The economic analysis of PID ducts reveals their cost-effective excellence compared to other investment types. The benefit-cost ratio of 4.73 and a payback period of 1.48 years show the financial advantages offered by PID ducts. With their affordability, efficiency, and simplicity, PID ducts emerge as the most attractive option for investors seeking long-term profitability and sustainability in construction projects.

GREEN AND SUSTAINABLE TECHNOLOGY IN THE GHANAIAN CONSTRUCTION INDUSTRY

Green and sustainable technologies pave the way for environmentally friendly and improve the conservation of natural resources. The study examined the application of green and sustainable technology within the school-built environment in Cape Coast Metropolis, Ghana. The qualitative research method was adopted to collect 92 responses from professionals and other stakeholders in the built environment, via a self-administered questionnaire. Data collected was analyzed using both descriptive statistical and relative importance index (RII). Findings show that thermal and photovoltaic solar energy, utilization of construction and demolition waste products were the most common and more familiar green and sustainable technologies in the built environment. The study also revealed the reduction in waste generation, improvement of indoor air quality, and savings of natural resources as positive impacts of applying green and sustainable technologies. Further findings revealed the unavailability of skilled human resources for the installation of the technologies, high research, and development costs, and much time consumption as piercing negative impacts of the green technology application in the built environment. Stakeholders in the built environment should apply and utilize green technologies to reduce the overall usage and consumption of energy and other raw materials to minimize the effects of global warming and improve the quality of air and water, as well as general projects.

A review of antimicrobial implications for improving indoor air quality

A review of antimicrobial implications for improving indoor air quality

Pilot Study on the Production of Negative Oxygen Ions Based on Lower Voltage Ionization Method and Application in Air Purification

In the current highly industrialized living environment, air quality has become an increasing public health concern. Natural environments like forests have excellent air quality due to high concentrations of negative oxygen ions originating from low-voltage ionization, without harmful ozone. Traditional negative oxygen ion generators require high voltage for corona discharge to produce ions. However, high voltage can increase electron collisions and excitations, leading to more dissociation and recombination of oxygen molecules and consequently higher ozone production. To address the challenge of generating negative oxygen ions without accompanying ozone production, this study designed and constructed a low-voltage negative oxygen ion generator based on nanometer-tip carbon fiber electrodes. The advantage of this device lies in the high curvature radius of carbon fibers, which provides high local electric field strength. This allows for efficient production of negative oxygen ions at low operating voltages without generating ozone. Experiments demonstrated that the device can efficiently generate negative oxygen ions at a working voltage as low as 2.16 kV, 28% lower than the lowest voltage reported in similar studies. The purification device manufactured in this study had a total decay constant for PM2.5 purification of 0.8967 min−1 within five minutes, compared to a natural decay constant of only 0.0438 min−1, resulting in a calculated Clean Air Delivery Rate (CADR) of 0.1535 m3/min. Within half an hour, concentrations of PM2.5, PM1, PM10, formaldehyde, and TVOC were reduced by 99.09%, 99.40%, 99.37%, 94.39%, and 99.35%, respectively, demonstrating good decay constants and CADR. These findings confirm its effectiveness in improving indoor air quality, highlighting its significant application value in air purification.