Indoor Air Quality Monitoring Research Articles

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.

Effects of reaction pH on regular nanorods and hierarchically structured β-Ga2O3 and their isopropanol sensing capabilities

Real-time detection of isopropanol is important for indoor air quality monitoring to improve human health. In this study, regular and hierarchical nanorod-based β−Ga2O3 morphological features were prepared using the microwave-assisted hydrothermal method following the variation of the reaction pH levels. A systematic study on their gas sensing performances was conducted to evaluate their potential as isopropanol gas sensing platforms. The sensor response and response times were directly controlled by morphology of β−Ga2O3. The randomly oriented β−Ga2O3 nanorods presented the highest response of 6.7 towards 90 ppm isopropanol while the β−Ga2O3 nanodandelions showed the fastest response/recovery times of 47/25 s. The observed variation in the gas sensing performances of the different β−Ga2O3 structures can be attributed to changes in morphological, textural, and compositional properties induced by the controlled reaction pH levels.

Reengineering Indoor Air Quality Monitoring Systems to Improve End-User Experience.

This paper presents an indoor air quality (IAQ) monitoring system designed for a better end-user experience. The monitoring system consists of elements, from the monitoring sensor to the monitoring interface, designed and implemented by the research team, especially for the proposed monitoring system. The monitoring solution is intended for users who live in houses without automatic ventilation systems. The air quality sensor is designed at a minimum cost and complexity to allow multi-zone implementation without significant effort. The user interface uses a spatial graphic representation that facilitates understanding areas with different air quality levels. Presentation of the outdoor air quality level supports the user's decision to ventilate a space. An innovative element of the proposed monitoring interface is the real-time forecast of air quality evolution in each monitored space. The paper describes the implementation of an original monitoring solution (monitoring device, Edge/Cloud management system, innovative user monitoring interface) and presents the results of testing this system in a relevant environment. The research conclusions show the proposed solution's benefits in improving the end-user experience, justified both by the technical results obtained and by the opinion of the users who tested the monitoring system.

BTEX Assessment among Informal Charcoal-Burning Food Traders for Cleaner and Sustainable Environment

This study assessed the cleaner and sustainable environment by measuring emission levels of benzene, toluene, ethylbenzene, and xylene (BTEX) from informal food traders using charcoal as the primary source of energy at a flea market in Fordsburg, Johannesburg. Volatile organic compounds (VOCs) were measured using a real-time monitor (MiniRae 3000 photoionization detector); an indoor air quality (IAQ) monitor was used to monitor environmental parameters and passive samplers in the form of Radiello badges, which were used to determine BTEX emissions from charcoal used during food preparation. Measurements were taken at 1.5 m above ground assuming the receptor’s breathing circumference using PID and Radiello. PID data were downloaded and analyzed using Microsoft Excel(Version 2019). Radiellos were sent to the laboratory to determine the BTEX levels from the total VOCs. The total volatile organic compound (TVOC) concentration over the combustion cycle was 306.7 ± 62.8 ppm. The flaming phase had the highest VOC concentration (547 ± 110.46 ppm), followed by the ignition phase (339.44 ± 40.6 ppm) and coking with the lowest concentration (24.64 ± 14.3). The average BTEX concentration was 15.7 ± 5.9 µg/m3 corresponding to the entire combustion cycle. BTEX concentrations were highest at the flaming phase (23.6 µg/m3) followed by the ignition (13.4 µg/m3) and coking phase (9.45 µg/m3). Ignition phase versus the flaming phase, there was a significant difference at 95% at a p-value of 0.09; ignition phase versus the coking phase, there was a significant difference at 95% at a p-value of 0.039; and coking phase versus the flaming phase, there was a significant difference at 95% at a p-value of 0.025. When compared to the occupational exposure limits (OELs), none of the exposure concentrations (BTEX) were above the 8 h exposure limit. The findings of this study suggest that charcoal, as a source of energy, can still be a useful and sustainable fuel for informal food traders. Shortening the ignition and flaming phase duration by using a fan to supply sufficient air can further reduce exposure to VOCs.

The Metrological Qualification of Commercial VOC Multisensor Systems: A Mandatory Step Prior to Indoor Air Quality Monitoring

The Metrological Qualification of Commercial VOC Multisensor Systems: A Mandatory Step Prior to Indoor Air Quality Monitoring

Easy-to-Use MOX-Based VOC Sensors for Efficient Indoor Air Quality Monitoring.

This research paper presents a case study on the application of Metal Oxide Semiconductor (MOX)-based VOC/TVOC sensors for indoor air quality (IAQ) monitoring. This study focuses on the ease of use and the practical benefits of these sensors, drawing insights from measurements conducted in a university laboratory setting. The investigation showcases the straightforward integration of MOX-based sensors into existing IAQ monitoring systems, highlighting their user-friendly features and the ability to provide precise and real-time information on volatile organic compound concentrations. Emphasizing ease of installation, minimal maintenance, and immediate data accessibility, this paper demonstrates the practicality of incorporating MOX-based sensors for efficient IAQ management. The findings contribute to the broader understanding of MOX sensor capabilities, providing valuable insights for those seeking straightforward and effective solutions for indoor air quality monitoring. This case study outlines the feasibility and benefits of utilizing MOX-based sensors in various environments, offering a promising avenue for the widespread adoption of user-friendly technologies in IAQ management.

Synergy in Action: Integrating Environmental Monitoring, Energy Efficiency, and IoT for Safer Shared Buildings

Shared public buildings have become centers of innovation, integrating advanced technologies to meet evolving societal needs. With a heightened emphasis on occupants’ health and well-being, these buildings serve as hubs for technological convergence, facilitating seamless connectivity and intelligent data analysis and management. Within this context, environmental monitoring emerges as a foundational element, pivotal to all aspects of building management. This article provides findings from the nationally funded RE-START project, which focuses on shared public buildings, with special regard to educational and medical facilities. The project explores enhanced indoor air quality monitoring, focusing on CO2 concentration that is directly correlated with occupancy, as a fundamental element for developing health and safety protocols, energy efficiency strategies, the integration of smart building technologies, and data-driven energy management. The intersection of environmental monitoring, energy efficiency, security, and IoT technologies in in indoor spaces is relevant. The outcomes of the study reveal the delicate nature of all the involved components, which need to be carefully developed in an integrated manner.

Air Quality Assessment Based on a Smart Locally CO2 Monitoring System with Validation by a Reference Instrument

This article deals with the development and implementation of a low-cost smart air quality monitoring device. The study aims to develop a simple, efficient, and cheap device for real-time monitoring of Carbon dioxide (CO2) concentration and atmospheric parameters such as temperature (T) and relative humidity (RH). The realized device consists of sensors, a data storage system, a programmable card, and wireless modules for Internet of Things (IoT). It is designed for indoor and outdoor air quality monitoring. Wireless communication between the device and the control PC is ensured by the ZigBee protocol. The MH-Z14A sensor was calibrated according to the manufacturer’s recommendations and then experimentally in the laboratory. A calculation of the CO2 regression line for the devices using the least squares method gave R2 = 0.6889. The slope test using the Student method at a significant coefficient of 1% threshold and 19 degrees of freedom gave t(1%; 19) = 2.539. This illustrates that the result obtained by the realized device has less than a 1% chance of being obtained at random. An investigation was carried out to assess air quality because following the proliferation of pollutants, the normal concentration of atmospheric CO2 (400 ppm) has considerably changed. Thus, the data processed are outdoor concentrations collected in November 2022 in some localities of the Adamawa Region, Cameroon. The average values of CO2 concentration measured in four subdivisions are 497.30 ± 11.32 ppm in Ngaoundéré 1, 481.83 ± 14.90 ppm in Ngaoundéré 2, 568.63 ± 25.03 ppm in Martap and, 624.14 ± 3.96 ppm in Minim. Martap and Minim are among the most important bauxite deposits in the world. These CO2 values higher than the normal atmospheric concentration indicate a moderate Air Quality Index (AQI) in these cities during the measurement period. The designed device is inexpensive, reliable, and appropriate for air quality monitoring.

Impact of cotton dust, endotoxin exposure, and other occupational health risk due to indoor pollutants on textile industry workers in low and middle- income countries

The textile industry consists of several units that engage different processes namely ginning, spinning, weaving, dyeing, printing, and several other processes which required for converting raw cotton fiber into finished fabrics. Exposure to cotton dust, endotoxin, chemicals, noise, and musculoskeletal disorders causes several health-related hazards to textile workers. This review article aims to study the health issues due to various risk factors associated with the working environment in detail and its impacts on workers' health. This review article also reports dust and endotoxin concentrations in indoor environments of textile industries, as well as discusses the association between workplace exposure to cotton dust, endotoxin, and the prevalence of respiratory disorders. In this review, the focus is also given to the prevalence of indoor pollutants like Particulate Matter (PM), Carbon dioxide (CO2), Carbon monoxide (CO), and Volatile Organic Compounds (VOCs), Formaldehyde (HCHO) in the workplace and its effects on human health. The study expands to other aspects that influence human comfort and health during working hours like occupational noise, musculoskeletal disorders, and eyesight problems. In addition, the advanced technologies for monitoring indoor air quality for control and reduction of pollutants indoor environment the current regulatory limits of cotton dust and indoor pollutants, and suggestions to enhance the occupational safety and health conditions in textile sectors are also pointed out. In conclusion, the current study stresses the need to regulate and apply international standards in the textile sector to prevent short- and long-term occupational illness.

Indoor Air Quality Monitoring and Automatic Ventilation System

Indoor Air Quality Monitoring and Automatic Ventilation System

IoT Based Air Quality Monitoring and Controlling System for Hospital

This project introduces an IoT based Air Quality Monitoring and Controlling System tailored for hospital environments. Utilizing a variety of sensors, including those for particulate matter, carbon dioxide, and volatile organic compounds, the system ensures continuous real-time monitoring of indoor air quality. NodeMCU facilitates wireless communication, enabling the transmission of data to a central server or cloud platform. Hospital staff can remotely monitor air quality conditions, receiving threshold alerts in the event of pollutant levels surpassing predefined limits. The system integrates a controlling mechanism, allowing for the activation of ventilation systems or air purifiers based on the collected data. Energy efficiency is prioritized through intelligent control of air quality devices. Historical data analysis enables administrators to identify patterns and improve overall air quality management. The system seamlessly integrates with existing hospital infrastructure and is designed for scalability, ensuring adaptability to evolving needs. Overall, this IoT-based solution offers a smart and automated approach to maintaining a healthy indoor environment in hospital settings.

Long-Term Characterization of Indoor Air Quality at a Research Area Building: Comparing Reference Instruments and Low-Cost Sensors

Indoor particle number size distribution (0.3-10 μm), equivalent black carbon (eBC), and Ångström absorption exponent (AAE) data were collected in real conditions, over a ten-month period at a research area building, in a semirural site, to characterize indoor aerosol loading. Additionally, during the campaign, emissions from four indoor sources commonly used at the site (incense, traditional cigarettes, electronic cigarettes, and heat-not-burn products) were studied during short-term experiments with the support of ultrafine particle (UFP) monitoring. Two particle low-cost sensors (PM LCS), Sensirion SPS30 (0.3-10 μm), were evaluated in the long-term campaign and during fast emission processes, to assess their accuracy and reliability. Penetration and infiltration of both fine and coarse particles from outdoor traffic, domestic heating, and dust resuspension were inferred as the main sources of indoor aerosols on a long-term basis. Moreover, long-range transported dust aerosols were found to influence indoor coarse number concentration. Among the source events, heat-not-burn (HNB) product resulted in the lowest effect on indoor air quality, whereas the highest AAE values from incense and traditional cigarettes suggest the brown carbon (BrC) production. The highest emission of UFP was caused by electronic cigarettes (e-cig), which spanned particles from the ultrafine to the coarse fractions. This was likely due to the release of metal and silicate from the coil. Analysis of number size distributions of the four experiments revealed the emission of fine particles (0.3-1 μm) and super micron particles. SPS30s performance was satisfactory in terms of accuracy, precision, and durability, indicating that these devices are suitable for monitoring indoor air quality. Additionally, the two PM LCS were able to detect all simulated fast emission sources.

Experimental assessment of impact of different ventilation modes on cognitive and academic performance: A study based on classrooms in Türkiye

In closed spaces, such as classrooms, poor ventilation, indoor exposure to CO2, and non-optimal humidity and temperature conditions are global concerns associated with health and performance. This study experimentally assesses the effects of different ventilation modes on the air quality parameters and cognitive and academic performances of 120 s-grade primary school children in two buildings with different characteristics during heating and non-heating seasons. Based on a retrospective analysis of 455 primary schools in Türkiye during 2017–2018, the study was conducted in six classrooms of the two representative school buildings. Indoor air quality monitoring and performance (of the students) assessment was carried out from December 9, 2019, to September 28, 2020. The non-heating season measurements were conducted during the COVID-19 pandemic. According to our findings, the traditionally constructed school without energy efficiency regulations exhibited the worse scenario. The success percentages of arithmetic attention in both traditional and natural ventilation modes were significantly lower in the non-heating season than in the heating season, which indicates the impact of using a facemask inside a classroom during cognitive tasks. This study demonstrated that the heating season is more critical than the non-heating season in terms of ventilation of closed spaces.

A BIM-enabled digital twin framework for real-time indoor environment monitoring and visualization by integrating autonomous robotics, LiDAR-based 3D mobile mapping, IoT sensing, and indoor positioning technologies

Existing indoor environment monitoring methods often fall short due to the lack of using standardized evaluation methods, missing spatial information, or the absence of user-friendly visualization interfaces. To address these limitations, this paper proposes a novel digital twin framework for real-time indoor environment monitoring and visualization by integrating Building Information Modeling (BIM), Internet of Things, autonomous robot-based mobile mapping and sensing, and indoor positioning technologies. The goal is to autonomously monitor indoor environmental conditions and provide real-time visualization using a standardized assessment index with estimated spatial information in BIM software. The proposed framework was demonstrated and validated in two indoor scenarios for air quality monitoring and visualization-related applications. Implementation results revealed that: the framework effectively captured spatial characteristics of air quality in small and medium-sized indoor spaces and intuitively visualized it using a BIM digital twin model; and, the ultra-wideband-based indoor positioning system achieved a nearly centimeter-level positioning precision. Practical interpretations of the results demonstrated that the proposed framework can not only detect and localize the potential sources of air pollutants but can also identify the possible causes of low indoor air quality. This study ultimately contributes to the body of knowledge by offering a novel and generic digital twin framework that seamlessly bridges various popular yet previously isolated technologies for better informing building facility management-related decisions. This paper is the first research work that integrates several emerging technologies (i.e., BIM, digital twins, IoT sensing, indoor localization/positioning/tracking, and robotics) for advancing real-time monitoring and visualization of indoor environmental conditions. While the proposed framework was applied for indoor air quality monitoring, it could be extended and used for various indoor environmental assessment and visualization-related applications.

Low-cost IoT-enabled indoor air quality monitoring systems: A systematic review

Indoor air quality (IAQ) is a critical challenge much less controlled in comparison with outdoor air quality. Bad IAQ is related to significant health complications such as respiratory problems, heart disease, and cancer. Many people spend most of their days inside buildings and don’t have air quality monitoring systems. Therefore, the occupants don’t know when the space has a higher quantity of pollutants than recommended, saturating the environment, and compromising people’s health. This is a problem that can be addressed by using Internet of Things (IoT) technologies to develop monitoring systems that allow a greater number of possibilities regarding the storage and processing of data and access to information by the end user, assisting the decision-making process regarding the indoor air pollution problem. Real-time data can be compared to default values, alerting the user of that situation, and suggesting an action to decrease the air pollutants concentration. There already are multiple solutions involving IoT-based technologies, many of them using low-cost sensors. Those are analyzed in this systematic review. Furthermore, the COVID-19 pandemic pointed out the importance of IAQ monitoring to evaluate the risk of contamination. The microcontrollers, IAQ parameters, sensors, data storage and visualization methods used in monitoring systems have been analyzed. The results show that most of the studies store data in Cloud systems and use Web platforms for data consulting. However, sensor calibration and efficient energy consumption are challenges that still exist.

CORRELATION BETWEEN CARBON DIOXIDE (CO2) AND RESPIRATORY ISSUES: A LITERATURE REVIEW

ABSTRACT The increasing levels of carbon dioxide (CO2) in the atmosphere due to human activities have raised concerns regarding potential health impacts, particularly on respiratory health. This literature review aims to examine the correlation between CO2 and respiratory issues by synthesizing the findings of relevant studies. A comprehensive search was conducted across academic databases, and studies were selected based on their relevance and methodological rigor. The review reveals that elevated CO2 levels are associated with respiratory symptoms, including coughing, wheezing, and shortness of breath, as well as the exacerbation of existing respiratory conditions. Additionally, exposure to increased CO2 concentrations can lead to respiratory acidosis, reduced lung function, and impaired gas exchange. Poorly ventilated indoor environments have been identified as potential hotspots for elevated CO2 levels, emphasizing the importance of monitoring indoor air quality. This review underscores the need for further research to elucidate the mechanisms underlying CO2-induced respiratory issues and to develop effective mitigation strategies. Understanding the correlation between CO2 and respiratory issues is crucial for public health interventions and policies aimed at minimizing the adverse impacts of elevated CO2 levels on respiratory health.

Adjusting surface coverage of Pt nanocatalyst decoration for selectivity control in CMOS-integrated SnO2 thin film gas sensors.

Smart gas-sensor devices are of crucial importance for emerging consumer electronics and Internet-of-Things (IoT) applications, in particular for indoor and outdoor air quality monitoring (e.g., CO2 levels) or for detecting pollutants harmful for human health. Chemoresistive nanosensors based on metal-oxide semiconductors are among the most promising technologies due to their high sensitivity and suitability for scalable low-cost fabrication of miniaturised devices. However, poor selectivity between different target analytes restrains this technology from broader applicability. This is commonly addressed by chemical functionalisation of the sensor surface via catalytic nanoparticles. Yet, while the latter led to significant advances in gas selectivity, nanocatalyst decoration with precise size and coverage control remains challenging. Here, we present CMOS-integrated gas sensors based on tin oxide (SnO2) films deposited by spray pyrolysis technology, which were functionalised with platinum (Pt) nanocatalysts. We deposited size-selected Pt nanoparticles (narrow size distribution around 3 nm) by magnetron-sputtering inert-gas condensation, a technique which enables straightforward surface coverage control. The resulting impact on SnO2 sensor properties for CO and volatile organic compound (VOC) detection via functionalisation was investigated. We identified an upper threshold for nanoparticle deposition time above which increased surface coverage did not result in further CO or VOC sensitivity enhancement. Most importantly, we demonstrate a method to adjust the selectivity between these target gases by simply adjusting the Pt nanoparticle deposition time. Using a simple computational model for nanocatalyst coverage resulting from random gas-phase deposition, we support our findings and discuss the effects of nanoparticle coalescence as well as inter-particle distances on sensor functionalisation.

Research Review Inquisitive on Indoor Air Quality Monitoring System Facilitate with Internet of Things

In recent days, Indoor Air Quality (IAQ) has become a matter of interest for researchers from both scientific and industrial community. During pandemic situation public settle more time at indoor in place of outdoor environment. With rapid growth in science and technology people have progressive necessity for active facility parameters with respect to indoor temperature, humidity and wind movement etc. Asthma, lung cancer, hypertension, cardiovascular issues, and respiratory illnesses are just a few of the chronic health issues that have been linked to frequent exposure to hazardous material in enclosed spaces. However, real-time monitoring technologies are being adopted in smart city projects to identify and remedy such unfavourable conditions, ultimately improving the general quality of life. This paper surveyed the current proposed IAQ monitoring systems in terms of Internet of Things (IoT). In addition, the research work highlights composition of diverse monitoring systems, research summary, challenges together implying future directions for the researchers. The current level of knowledge on the close relationship between IoT and IAQ is presented in this research.

Indoor air quality analysis and sustainable practices

A constant supply of fresh air is vital for eliminating harmful bacteria and supporting the body's immune system against viruses and infections. Poor indoor air quality poses significant health risks, affecting human well-being and productivity. To address this issue, indoor air quality analysis is essential for enclosed spaces like homes, offices, and schools. According to the United States Environmental Protection Agency, indoor air can be up to 1000 times more polluted than outdoor air, with modern lifestyles leading to people spending 80-90% of their time indoors. Air pollution, as reported by the World Health Organization, causes 7 million deaths annually, primarily affecting the lungs and increasing the risk of cardiovascular diseases. Monitoring indoor air quality parameters such as CO2 and humidity levels is crucial for a healthy lifestyle. By utilizing sensors like MQ135 and DHT11, we can measure indoor pollutants and evaluate ventilation systems' effectiveness. Automation, such as using servo motors for ventilation, helps maintain safe indoor air quality levels. This approach can be implemented across various sectors, including schools, malls, and offices, to create healthier environments. Ultimately, indoor air quality analysis plays a vital role in enhancing indoor air quality and promoting occupant well-being.

Design And Development of a Compact Carbon Gas Emission Monitoring Device for Private Vehicles

Poor air quality is a major concern in urban areas, with a large percentage of the population exposed to high levels of pollutants. Using sensor and monitoring technology, devices can automatically and periodically monitor indoor air quality. Containment measures should be taken when dangerous airborne chemicals are detected. Air pollution, both indoors and outdoors, causes health problems. The Philippines faces challenges in air quality reporting due to the high cost of monitoring equipment. A project is underway to collect real-time data using sensors and an Arduino Uno-based monitoring system. The power management design's PCB layouts were completed using two software applications: Eagle CAD for the nano power boost charger circuit and Ultiboard for the boost converter circuit. The layout design adhered to the IPC2221A standards, ensuring accurate component footprints and copper trace width, which were determined based on the current flow through the trace in the PCB design. The circuit boards were carefully sized to be smaller than 4“x4” to enable smooth integration into an air quality monitoring device. The integrated design functioned as a wireless sensing application, effectively monitoring air quality. The carbon gas monitoring system had the capability to detect and collect various gases, including Carbon Dioxide, Nitrogen Monoxide, Carbon Monoxide, and Dust Density. Additionally, it was equipped to measure temperature and humidity. Achieving this required using the Arduino Uno application for programming and incorporating an additional sensor, resulting in a cost-effective design solution. The prototype successfully integrated air quality sensors, microcontrollers, and communication modules. The system's performance was evaluated against existing testing centers, and the results were presented.