Improve Indoor Air Quality Research Articles

Machine-Learning-Assisted Descriptors Identification for Indoor Formaldehyde Oxidation Catalysts.

The development of highly efficient catalysts for formaldehyde (HCHO) oxidation is of significant interest for the improvement of indoor air quality. Up to 400 works relating to the catalytic oxidation of HCHO have been published to date; however, their analysis for collective inference through conventional literature search is still a challenging task. A machine learning (ML) framework was presented to predict catalyst performance from experimental descriptors based on an HCHO oxidation catalysts database. MnOx, CeO2, Co3O4, TiO2, FeOx, ZrO2, Al2O3, SiO2, and carbon-based catalysts with different promoters were compiled from the literature. Notably, 20 descriptors including reaction catalyst composition, reaction conditions, and catalyst physical properties were collected for data mining (2263 data points). Furthermore, the eXtreme Gradient Boosting algorithm was employed, which successfully predicted the conversion efficiency of HCHO with an R-square value of 0.81. Shapley additive analysis suggested Pt/MnO2 and Ag/Ce-Co3O4 exhibited excellent catalytic performance of HCHO oxidation based on the analysis of the entire database. Validated by experimental tests and theoretical simulations, the key descriptor identified by ML, i.e., the first promoter, was further described as metal-support interactions. This study highlights ML as a useful tool for database establishment and the catalyst rational design strategy based on the importance of analysis between experimental descriptors and the performance of complex catalytic systems.

Planning and design of an architectural energy supply system based on photovoltaic-thermal technology

China’s building energy consumption is growing and the energy consumption of the whole process of buildings accounts for more than 46.5% of the country’s total energy consumption, of which the proportion of energy consumption used for heating, ventilation and air conditioning is as high as 50%. Solar energy has the greatest potential to achieve energy conservation in buildings. Buildings are the best carrier for solar energy utilization because of the advantages of local collection and local application. The combination of solar energy and buildings can meet a variety of energy and health needs in buildings, among which solar photovoltaic and CSP building integration technology is an important way to reduce building energy consumption and improve indoor air quality. This article presents a PV/T-based thermal storage wall system that efficiently utilizes solar energy. It outlines the PV/T technology’s fundamental principles and provides a detailed description of the system’s construction and operation, highlighting critical components like the solid thermal storage medium and heat transfer via a heat pump. The analysis indicates improved energy utilization and favorable economic feasibility. This technology offers a practical solution for the construction industry, promoting sustainable energy practices and environmental conservation.

The effect of indoor air filtration on biomarkers of inflammation and oxidative stress: a review and meta-analysis of randomized controlled trials.

Improvement of indoor air quality is beneficial for human health. However, previous studies have not reached consistent conclusions regarding the effects of indoor air filtration on inflammation and oxidative stress. This study aims to determine the relationship between indoor air filtration and inflammation and oxidative stress biomarkers. We conducted an electronic search that evaluated the association of indoor air filtration with biomarkers of inflammation and oxidative stress in five databases (PubMed, Cochrane Library, EMBASE, Web of Science, and Scopus) from the beginning to April 23, 2023. Outcomes included the following markers: interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), C-reactive protein (CRP), malondialdehyde (MDA), 8-hydroxy-2deoxyguanosine (8-OHdG), and 8-iso-prostaglandinF2α (8-isoPGF2α). We extracted data from the included studies according to the system evaluation and the preferred reporting item for meta-analysis (PRISMA) guidelines and used the Cochraneriskofbiastool to assess bias risk. Our meta-analysis included 15 studies with 678 participants to assess the combined effect size. The meta-analysis demonstrated that indoor air filtration could have a marked reduction in IL-6 (SMD: -0.275, 95% CI: -0.545 to -0.005, p = 0.046) but had no significant effect on other markers of inflammation or oxidative stress. Subgroup analysis results demonstrated a significant reduction in 8-OHdG levels in the subgroup with < 1 day of duration (SMD: -0.916, 95% CI: -1.513 to -0.320; p = 0.003) and using filtrete air filter (SMD: -5.530, 95% CI: -5.962 to -5.099; p < 0.001). Our meta-analysis results depicted that indoor air filtration can significantly reduce levels of inflammation and oxidative stress markers. Considering the adverse effects of air pollution on human health, our study provides powerful evidence for applying indoor air filtration to heavy atmospheric pollution.

Solutions to Detect Air Quality in a Room and Improve It

Abstract: The project focuses on monitoring and improving indoor air quality by implementing an air quality detection system. Poor indoor air quality can have detrimental effects on health and well-being, from breathing difficulties to reduced cognitive function. Therefore, it is necessary to develop methods for effective monitoring and improvement of indoor air quality. In this project, we propose the use of sensors to detect various air pollutants such as particulate matter, volatile organic compounds (VOCs), carbon dioxide (CO2), and humidity levels. Sensor data will be collected and analyzed to assess the current state of air quality. Based on the analysis, appropriate measures will be taken to improve air quality, which may include ventilation modifications, air cleaners or other interventions. The aim of the project is to create a healthier and more comfortable indoor environment for residents by ensuring an optimal level of air quality.

Evaluating the Particulate Matter and Carbon Dioxide Reduction of Four Broad-leaved Evergreen Plants

Background and objective: Since people spend 70-80% of their time indoors, the quality of indoor air has become a crucial factor in overall health. Therefore, poor indoor air quality can have significant adverse effects on our well-being. Common indoor air pollutants are particulate matter (PM) and carbon dioxide (CO2). Plants can remove PM and CO2 through the photosynthesis process and leaf surfaces, and regulate the temperature and humidity of the air. By analyzing the PM and CO2 reduction of four broad-leaved evergreen plants, this study aims to provide data for air purification in indoor spaces.Methods: The four different plant species (Neolitsea sericea (Blume) Koidz., Coffea arabica L., Photinia glabra(Thunb.) Franch. and Sav., and Farfugium japonicum (L.) Kitam.) were selected for this study. Mosquito coils and a CO2 cylinder were the primary sources of PM and CO2. These pollutants were injected into a closed acrylic chamber with plants, and the air quality within the chamber was monitored for a duration of five hours. The plants' effectiveness in reducing carbon dioxide was evaluated through the clean air delivery rate (CADR), while their ability to reduce PM was assessed by analyzing the PM reduction rate. Photosynthetic rates and leaf area were also measured to determine the correlation between air pollution removal and these factors.Results: The ability to remove PM and CO2 varied among plants. Plants with higher rates of photosynthesis were more effective in reducing PM and CO2 than those with lower rates. Among the four plant species, C. arabica and P. glabra were more effective in removing PM and CO2 than the other species. The chamber containing plants exhibited higher humidity and lower temperatures compared to the chamber without plants.Conclusion: These findings suggest that plants can play a significant role in improving indoor air quality. Not only do they effectively reduce levels of PM and CO2, but they also contribute to the regulation of indoor temperature and humidity. The implications of these results highlight the potential of integrating plants into indoor spaces as a natural and multifaceted solution for creating healthier and more comfortable environments.

Review of energy-efficient HVAC technologies for sustainable buildings

This review paper provides a comprehensive examination of energy-efficient Heating, Ventilation, and Air Conditioning (HVAC) technologies for sustainable buildings. The focus is on exploring the latest advancements, benefits, challenges, and future prospects in the realm of HVAC systems designed to enhance energy efficiency and promote sustainability in building operations. The review begins with an overview of the importance of energy-efficient HVAC technologies in the context of sustainable building design and operation. It underscores the critical role of HVAC systems in reducing energy consumption, minimizing environmental impact, and enhancing occupant comfort and well-being. The paper delves into various categories of energy-efficient HVAC technologies, including advanced heating and cooling systems, ventilation strategies, and smart controls. Each category is examined in detail, highlighting key features, performance metrics, and real-world applications. Furthermore, the review evaluates the benefits associated with energy-efficient HVAC technologies, such as significant energy savings, reduced operating costs, improved indoor air quality, and enhanced building resilience. It also discusses the potential challenges and barriers to adoption, such as high upfront costs, complexity of implementation, and retrofitting existing buildings. The paper explores emerging trends and innovations in the field of energy-efficient HVAC technologies, including the integration of renewable energy sources, smart sensors and actuators, and predictive maintenance algorithms. These advancements have the potential to further optimize energy performance, increase system reliability, and enable proactive management of HVAC systems. In conclusion, the review emphasizes the importance of energy-efficient HVAC technologies as a cornerstone of sustainable building practices. It underscores the need for continued research, innovation, and collaboration among stakeholders to overcome existing challenges and unlock the full potential of energy-efficient HVAC systems in contributing to a more sustainable built environment. Overall, this comprehensive review provides valuable insights into the current state of energy-efficient HVAC technologies, their applications, benefits, and challenges, while also highlighting opportunities for future advancements and their crucial role in achieving sustainability goals in the building sector.

Development of an IoT-Integrated Cigarette Smoke Detection System Using MiCS-5524 Sensor

Cigarette smoke is one of the primary causes of indoor air pollution, leading to various adverse health impacts. To address this issue, this research aims to design of a cigarette smoke detection device using the MiCS-5524 sensor integrated with the Internet of Things (IoT). This device can detect the level of cigarette smoke in indoor spaces and provide alerts through an LCD, a buzzer, and the Blynk application. Furthermore, the device can activate an exhaust fan to remove cigarette smoke from the room. The device employs the NodeMCU ESP8266 microcontroller as the central control unit for system operation and internet communication. The MiCS-5524 sensor was chosen for its high sensitivity to carbon monoxide (CO), a major component of cigarette smoke. Test results demonstrate that the device functions effectively and accurately in detecting cigarette smoke and responding to indoor air conditions. It is anticipated that this device will contribute to improving indoor air quality and human health.

Comprehensive performance investigation of a novel thermal catalytic semi-transparent PV double-skin ventilated window integrated with CdTe cells

Human health is adversely impacted by indoor formaldehyde. Given that buildings with conventional PV-DSVs fail to improve indoor air quality in the indoor or outdoor air circulation mode without any air handling devices. To remove indoor formaldehyde, a thermal-catalytic CdTe PV double-skin ventilated window is proposed. A corresponding mathematical model was established and validated against experiment data. Based on the validated model, the thermal, electrical, daylighting, and formaldehyde degradation performances were investigated and compared with a conventional PV-DSV (PV-CDSV). Additionally, parametric analysis was conducted to analyse impacts of four factors, including the area of catalytic coating, the window-to-wall ratio, outdoor solar radiation, and ambient temperature, on the energy performance of the proposed window. Main results are: (1) The proposed window had a higher power output but a bit lower thermal efficiency than PV-CDSV, and it had a higher ηtotal in winter, which reached 35.35 % and was 31.45 % higher than that of the PV-CDSV. (2) The net energy consumption of PV-TCDSV increased by 6.59 % and 6.26 % compared with PV-CDSV in winter and summer, respectively. (3) Among the four influencing factors, the solar radiation and ambient temperature had strong impacts on the effectiveness of formaldehyde degradation.

Experimental study on the effect of adjacent near-wall heat sources on the particle deposition

Adjacent near-wall heat sources are widely used in indoor environments. It is important to investigate the particle deposition under the influence of coupled thermal plumes arising from adjacent near-wall heat sources to improve indoor air quality and control harmful particle deposition. Thus, this study scrutinizes the behavior of thermal plumes emanating from adjacent near-wall heat sources, focusing on the deposition of particles with diameters of 0.3 μm, 0.5 μm, 1.0 μm and 3.0 μm on the wall behind the heat sources. These findings are juxtaposed with the pattern of particles with varying sizes situated above the single near-wall heat source and away from the heat sources. The study delves into the impact of varying surface temperatures and the distance from the wall behind the heat sources, as well as the top surface of the heat source, on particle deposition in 29 distinct cases. The results indicate that the deposition velocity of particles with the same size is highest above the adjacent near-wall heat sources, followed by that of a single near-wall heat source, and finally, locations away from the near-wall heat source. Also, the decay rate loss coefficient of particles with the same size above the adjacent near-wall heat sources increases with a decrease in the distance of the heat sources from the wall behind them, an increase in the temperature of the heat sources, and a reduction in distance from the top surface of heat sources.

Exploring airborne fungal contaminations and air quality pollution in nine ancient stone temples, Surin, Thailand.

This study provided crucial insights into the concentrations of airborne fungi, environmental parameters, and atmospheric pollution in Thailand's ancient stone temples. Airborne fungi were identified based on morphological characteristics. Airborne fungi, meteorological parameters, and atmospheric pollutants concurrently assessed during each sampling event, evaluating indoor/outdoor ratio. Prevalent genera included Penicillium (14.36%), Aspergillus (10.94%), Cladosporium (10.74%), Rhizopus (6.31%), and Fusarium (5.90%), with an average fungi concentration of 4884.46 ± 724.79CFU/m3. Eighteen fungal species out of the 64 airborne fungi identified were well-known serious pathogenic agents, contributing not only to structural deterioration but also to human health. Significant variations were observed between indoor and outdoor environments and across diverse landscapes, particularly for PM10 (ranging from 43.47 to 121.31µg/m3) and PM2.5 (ranging from 29.59 to 89.60µg/m3), with intensive incense burning identified as a prominent source of indoor atmospheric pollution. Historical temples, particularly situated in urban areas, were identified as significant reservoirs of airborne fungi. Correlations between meteorological parameters and pollutants revealed strong associations. Furthermore, principal component analysis (PCA) and cluster analysis elucidated distinct patterns in airborne fungal concentrations and contaminations. This study analyzed environmental factors, pollutants, airborne fungi, and geographical variations from July 2020 to March 2021. Understanding prevalent genera, airborne fungi concentrations, pathogenic species, biodeterioration, and environmental dynamics provided strategies for improving indoor air quality and mitigating airborne fungal contamination in archaeological buildings worldwide.

Technological progression associated with monitoring and management of indoor air pollution and associated health risks: A comprehensive review

AbstractIndoor air pollution (IAP) is a prevalent issue, and in the absence of any concrete and stringent guidelines, particularly in developing countries the concern becomes graver. Technological strategies like the use of the Internet of Things (IoT) and cloud computing have been explored for real‐time monitoring and these interventions may be investigated to improve indoor air quality (IAQ) and human health. This review article explores the prospects of IoT and smart environments for the improvement of indoor living conditions through automation. Some specific interference like sensors, air pollution simulations and modeling, the concept of smart ventilation, and fuzzy logic controllers (FLC) have been elaborated with pieces of evidence taken from previously published studies in leading indexing databases. Furthermore, some automated health risk assessment tools like the Human exposure model (HEM), Integrated Fuzzy‐stochastic modeling (IFSM), and proximity and interpolation models have also been described. The findings suggested that IoT‐based gadgets require ambient intelligence capabilities for ambient assisted living (AAL). The studies showed that innovations in technology like sensors and modeling techniques may yield crucial information on pollution exposure enabling long‐term and sustainable predictions. However, efficient AAL systems may also face challenges in designing interfaces, usability, and accessibility. Although IoT can aid in mimicking real‐world scenarios, nevertheless its‐micro spatial scale application requires thorough investigation for reliable information extraction.

Prioritising Actions for Improving Classroom Air Quality Based on the Analytic Hierarchy Process: Case Studies in China and the UK

The air quality in classrooms significantly impacts school children’s health and learning performance. It has been reported worldwide that classroom air quality does not meet the required standard and actions are pledged for improvement. However, it poses a challenge for decision-making in terms of prioritising taking-up measures. The aim of this study is to propose a method of identifying the action measures for improving classroom air quality and prioritising them. Case studies in the UK and China were conducted, and the key measures were identified through literature studies, open-ended questionnaire surveys, and workshop discussions, which are classified into three categories: B1, policy; B2, technology; and B3, information sharing. The analytical hierarchy process (AHP) is applied in the prioritisation of the action measures. A total of 138 teachers and parents from China and the UK participated in this case study. The genetic algorithm-optimised Hadamard product (GAOHP) method is applied to justify the consistency ratio (CR) within the required threshold value in order to ensure the consistency of the subjective perception and the accuracy of comparative weights. The results show that item B2, technology, is the most desired measure by both Chinese and British parents and teachers, despite the deviation from the optimal choice in China and the UK. Among the proposed action measures, the UK respondents strongly expected air purifiers with natural ventilation as opposed to their Chinese counterparts preferring to share the real-time status of classroom air quality. Our work will provide strong support for the subsequent selection of indoor air quality improvement strategies for schools.

Eco-Friendly Sanitization of Indoor Environments: Effectiveness of Thyme Essential Oil in Controlling Bioaerosol Levels and Disinfecting Surfaces.

Bioaerosols and pathogens in indoor workplaces and residential environments are the primary culprits of several infections. Techniques for sanitizing air and surfaces typically involve the use of UV rays or chemical sanitizers, which may release chemical residues harmful to human health. Essential oils, natural substances derived from plants, which exhibit broad antimicrobial properties, could be a viable alternative for air and surface sanitation. The objective of this study has been to investigate the efficacy of thyme essential oil (TEO) in environmental sanitation processes. In Vitro assays through agar well diffusion, disk volatilization and tube dilution methods revealed significant antimicrobial activity of TEO 100% against foodborne and environmental isolates, with both bacteriostatic/fungistatic and bactericidal/fungicidal effects. Therefore, aqueous solutions of TEO 2.5% and 5% were formulated for air sanitation through nebulization and surface disinfection via direct contact. Bioaerosol samples and surface swabs were analyzed before and after sanitation, demonstrating the efficacy of aqueous solutions of TEO in reducing mesophilic and psychrophilic bacteria and environmental fungi levels in both air and on surfaces. The obtained results prove the antimicrobial potential of aqueous solutions of TEO in improving indoor air quality and surface cleanliness, suggesting thyme essential oil as an effective and safe natural sanitizer with minimal environmental impact compared to dangerous chemical disinfectants.

The Influence of Window-to-Wall Ratio (WWR) on Airflow Profile for Improved Indoor Air Quality (IAQ) in a Naturally-Ventilated Workshop in a Hot-Humid Climate

Indoor air quality (IAQ) has become a major concern worldwide as indoor air pollution rapidly becomes a public health issue. IAQ plays a pivotal role in occupants' health and comfort and influences their productivity and work efficiency. Many studies have been done on IAQ of common building spaces such as offices, residential buildings, and educational institutions, but the availability of IAQ studies on workshops is limited, considering the significant implications for workers' health and performance. Thus, this paper aims to study the effectiveness of natural ventilation in a workshop based on the influence of different window-to-wall ratios (WWR). Electronic databases are utilized to obtain data, and the findings collected are categorized based on research methodology, issues, and findings. The air movement as part of the physical parameters of IAQ is studied through the application of Computational Fluid Dynamic (CFD) simulation to observe and analyse the airflow pattern and the air velocity of the naturally ventilated workshop with different WWRs. The research outcome underscores the ideal WWR for effective natural ventilation in a workshop is 0.30. However, the study observes that the effectiveness decreases as WWR exceeds 0.50. Further research on the openings' location, inlet, and outlet sizes and application of mechanical ventilation can be conducted to improve the measurement of the IAQ effectiveness in a naturally ventilated workshop.

Exploring the filtration performance and usage cost of commercial fiber air filters for capturing moxa smoke aerosols

Traditional moxibustion treatments plays a role in preventing and treating COVID-19 while aggravating indoor air pollution. Therefore, commercial fiber air filters (CFAF) are widely used to improve indoor air quality to reduce the risk of people being exposed to moxa smoke aerosols (MSA). Considering that there were few reports on the performance of CFAF for capturing MSA, we explored in detail the effects of face velocity and MSA particle size on the filtration performance of CFAF to fill this gap. Then, we analyzed the deposition characteristics of MSA on fibers in combination with SEM images. In addition, the long-term stability, cleaning performance and MSA holding capacity of the CFAF were further characterized by tests of continuous operation, clean air delivery rate (CADR) and MSA loading. The results indicated that the CFAF had the potential to efficiently capture MSA in indoor air at an acceptable annual usage cost (AUC). Specifically, the pristine CFAF had high classification counting efficiency (CCE) (99.1 %-100 %), medium pressure drop (150.3 Pa), and low quality factor (0.04 Pa−1) at the face velocity of 0.3 m·s−1. Note that increasing face velocity not only decreased CCE and quality factor but also significantly increased pressure drop. Furthermore, the CFAF maintained excellent CCE (99.5 %-100 %) after 24-h of continuous operation at high concentrations of MSA (100 mg·m−3), while the pressure drop increased to 203.7 Pa. Obviously, the deposited MSA severely clogged the inter-fiber pores, which explained the fact of the rapid increase in the pressure drop of the CFAF. Of course, the high CADR value (66.6 m3·h−1) also demonstrated that the CFAF had the ability to efficiently remove MSA from confined place. Moreover, a total of 216.3 g MSA can be captured by the CFAF when the final pressure drop reached 300 Pa, which meant that further increasing the MSA holding capacity would be the focus of future research by filter media manufacturers. Finally, through the established mathematical model, we successfully predicted the service life (86 days) and the total AUC (276 $·year−1) of using the CFAF to capture MSA. This work is expected to provide a useful reference for routine maintenance and design optimization of existing CFAF.

Development of Particle Filters for Portable Air Purifiers by Combining Melt-Blown and Polytetrafluoroethylene to Improve Durability and Performance

Improving indoor air quality through the use of air purifiers has become a major focus, with emphasis on developing filters with high efficiency, high holding capacity, and low-pressure drop to improve the clean air delivery rate (CADR) for air purifiers. However, although most studies focused on developing media and evaluating their performance, few studies have reached the employment for a pleated filter. In this study, we newly synthesized flat media and pleated filters by combining polytetrafluoroethylene membrane (PT) and melt-blown (MB) materials (PM) and compared its initial performance to that of other air purifier filters (MB, glass fiber, and PT). Additionally, we analyzed how the performance changed after the particles were loaded. The initial efficiency of the PM filter showed a higher quality factor (QF) than the other filters. Furthermore, when more particles were loaded, the penetration of the PM did not change. These results demonstrate the potential of the PM. However, the CADR and submicron-sized (0.02–0.113 μm) CADR (sCADR) were highest for the MB filter due to the initial pressure drop. Therefore, additional improvements are required to apply the PM in air purifiers. However, the results suggest that the PM can be a new alternative for air purifier filters used in medical centers or facilities with vulnerable populations where a high-efficiency particle air (HEPA) filter must be used.

Early life ambient air pollution, household fuel use, and under-5 mortality in Ghana

IntroductionEnvironmental exposures, such as ambient air pollution and household fuel use affect health and under-5 mortality (U5M) but there is a paucity of data in the Global South. This study examined early-life exposure to ambient particulate matter with a diameter of 2.5 µm or less (PM2.5), alongside household characteristics (including self-reported household fuel use), and their relationship with U5M in the Navrongo Health and Demographic Surveillance Site (HDSS) in northern Ghana. MethodsWe employed Satellite-based spatiotemporal models to estimate the annual average PM2.5 concentrations with the Navrongo HDSS area (1998 to 2016). Early-life exposure levels were determined by pollution estimates at birth year. Socio-demographic and household data, including cooking fuel, were gathered during routine surveillance. Cox proportional hazards models were applied to assess the link between early-life PM2.5 exposure and U5M, accounting for child, maternal, and household factors. FindingsWe retrospectively studied 48,352 children born between 2007 and 2017, with 1872 recorded deaths, primarily due to malaria, sepsis, and acute respiratory infection. Mean early-life PM2.5 was 39.3 µg/m3, and no significant association with U5M was observed. However, Children from households using “unclean” cooking fuels (wood, charcoal, dung, and agricultural waste) faced a 73 % higher risk of death compared to those using clean fuels (adjusted HR = 1.73; 95 % CI: 1.29, 2.33). Being born female or to mothers aged 20–34 years were linked to increased survival probabilities. InterpretationThe use of “unclean” cooking fuel in the Navrongo HDSS was associated with under-5 mortality, highlighting the need to improve indoor air quality by introducing cleaner fuels.

Assessment of some air pollutants in the Sanctuary of the Beata Vergine dei Miracoli (Saronno, Italy) and first evaluation of a new axial passive sampler for nitrogen dioxide

In the present study the concentration of some air pollutants (nitrogen dioxide, sulphur dioxide, hydrogen sulphide, ammonia and BTEX, i.e. benzene, toluene, ethylbenzene and xylene) was monitored inside and outside the Sanctuary of the Beata Vergine dei Miracoli (Saronno, Italy) by passive air sampling (using radial samplers), during two sampling periods in 2022 (April 27-May 11 and May 11-May 25). Concurrently, particulate matter (PM10 and PM2.5) concentration was determined by using sensors based on laser scattering technology. Moreover, we took advantage of the location of this sanctuary (proximity to an air monitoring central unit) to evaluate the performance of a new axial-type sampler for nitrogen dioxide. Sulphur dioxide concentration was in the range 0.8–3.1 µg/m3, with outdoor values higher than indoor ones, whereas no detectable concentrations of hydrogen sulphide were found (<0.1 µg/m3). A different trend was observed for ammonia, where indoor concentrations were higher than outdoor ones (3.6–5.5 vs 2.7–3.1 µg/m3). Among BTEX, only for benzene statistical differences (p-value < 0.05) between the indoor and outdoor concentrations were found, suggesting additional indoor sources for this hydrocarbon. Toluene results as the most abundant among these hydrocarbons (1.7–2.3 µg/m3) in outdoor environments, whereas, in indoor environments, benzene has the higher concentration (6–9 µg/m3). The indoor concentrations of NO2 (15.4–22.2 µg/m3 for radial samplers and 48–60 µg/m3 for axial samplers) are not only much higher than the recommended limit values to guarantee proper conservation of artefacts (5 µg/m3), but also close to the values for human health preservation (40 µg/m3), suggesting the need of proper strategy to improve indoor air quality inside the Sanctuary. The preliminary results obtained for the new axial-type sampler for nitrogen dioxide are very encouraging, given the closeness of the obtained concentration data to those measured by monitoring central unit, even though further experiments will have to be carried out to validate this sampler.

Heated tobacco products: Potentials of harm reduction, improvement of indoor air quality and the need for further studies

Air pollution is a major concern in the Philippines, with indoor and outdoor air pollution among the highest causes of mortality in the country. However, the latest regulations deal only with ambient outdoor air pollution. Indoor air pollution is seldom monitored or studied. Most of the official government monitoring data also deal with outdoor air pollution even if Filipinos spend more than 80% of their time indoors. Smoking indoors can be a cause of excess air pollutants in the indoor setting. Heated Tobacco products, newly introduced in the country, have been reported to reduce the harm of exposure to users to air pollutants. We investigated this through the review of 282 studies, research papers, books, and narratives about HTP use and their effects. These studies show reduced release of harmful and potentially harmful compounds (HPHC) in the aerosol and lower concentrations of HPHCs in the indoor environment when using HTPs as compared to tobacco smoke. Short term pre-clinical studies also show a reduction in the biomarkers for potential exposure to these HPHCs and risk calculations have shown a reduction in cancer potencies across populations. While long-term epidemiological studies are still required to determine with finality the risks that HTP use may have, there is already wide agreement in the initial results that the complete switch to HTP use from cigarette smoking presents less risks of harm. The review, however, shows that much has to be studied about the manner by which HTPs can affect indoor air quality in tropical countries such as the Philippines.

Energy-efficient operation of portable air cleaners based on real-time prediction of non-uniform concentrations of indoor air pollutants in open offices

In an open office environment with high occupant density and random occupancy patterns, excessive energy consumption is often observed because mechanical ventilation (MV) is usually designed and operated assuming a full-occupancy-based ventilation rate (VR). Considering the duo challenges of post-pandemic and climate change, this study proposes a real-time monitoring and optimization approach for operating portable air cleaners (PACs) to assist and reduce the energy consumption of the MV while maintaining the minimal VR and improving indoor air quality (IAQ). The approach was as follows. First, by assuming four VRs and 36 different emission sources, numerical simulations were conducted and validated based on an actual open office on non-uniform concentrations of a surrogate for indoor air pollutants (IAPs) throughout the breathing zone. Second, the pre- and post-purified IAP distributions were obtained using a limited number of sensors and trained by two artificial neural networks. Third, the real-time optimization of PACs’ on/off operation and placements was accomplished by the particle swarm optimization algorithm to balance energy output and improve IAQ simultaneously. Results showed that by deploying four sensors, the predictions of post-purifying concentrations were in acceptable accuracy (i.e., CV-RMSE <2.0%) within 30–40s. Using at most three PACs resulted in a significant decline in local IAP concentration levels. Meanwhile, an average reduction of total energy consumption of MV and PACs was 34.6% compared to using MV to reach the same levels. Overall, this study supports the use of PACs to assist MV in achieving energy efficiency and good IAQ.