Indoor Air Quality Analysis Research Articles

How to promote health in indoor living and working spaces: quali-quantitative analysis to evaluate the indoor air quality through users’ perception and low-cost sensors

Abstract It is well-known that humans spend most of their time in indoor spaces: what it is sometimes underestimated; however, is how much the space in which someone is can affect their abilities, feelings and even their mental and physical health. A team developed a methodology to allow the collection of useful data and giving rise to management strategies for guaranteeing healthy spaces, in terms of Indoor Environmental Quality (IEQ). In particular, the methodology is based on a quali-quantitative analysis of Indoor Air Quality (IAQ) supported by a questionnaire on users’ perception and well-being, based on a scoping review, and low-cost sensors for IAQ monitoring air contaminants (carbon dioxide, temperature, relative humidity, volatile organic compounds, etc.). In particular, for the quantitative analysis, the team adopted a method that considers the location of the sensors in different typology of settings with various solar exposures, ventilation systems, human occupancy, type of activity, etc. with the scope of testing the trends in different seasons. As well as the qualitative data collect several information about the users’ perceived comfort and the symptoms (headache, fatigue, etc.) during their stay. The data analysis highlights how the different users’ perceptions affect the conditions of the environmental units, in particular in crowded rooms (4-6 people). Adequate lifestyles, such as door and window-openings, regular air-changes, etc. can highly affect the performances and the productivity, as well as the quality of the spaces. In that sense the use of low-cost sensors with light signals can be helpful as strategy for informing the user of the state of the air and any actions to be implemented. In conclusion, starting from the methodology, the team gives rise to a decalogue of strategies and good habits that permits -through the support of low-cost sensors - to inform the users on how to guarantee healthy living and working spaces.

Computational Simulation and Analysis of Local Thermal Comfort and Indoor Air Quality in Space with Displacement Ventilation

Computational Simulation and Analysis of Local Thermal Comfort and Indoor Air Quality in Space with Displacement Ventilation

An Indoor Air Quality Analysis in Newly Constructed Apartments

This study analyzes the indoor air quality inspections of newly constructed apartments by the Busan Institute of Health and Environment for the last three years (2021-2023). Of the 41 inspections, 33 exceeded the recommended standard, and the average excess rate was 80.5%. When classified by measuring households, 148 out of 332 exceeded the standards, whereas, the average excess rate by household was 44.6%. Benzene was exceeded in two out of the 332 households; therefore, the excess rate was only 0.6%. However, the relative standard deviation was the largest, showing as the highest item in the scattergram. The average concentration of toluene was 1,006.0 µg/m3, which was 100.6% of the recommended standard and was exceeded by 138 households; hence, the excess rate was 41.6%. All six items(Formaldehyde, Benzene, Toluene, Ethylbenzene, Xylene, Styrene) reached the highest concentration in spring or summer when the indoor temperature increased. The average concentration of toluene in July was 1,922 µg/m3, close to 1.9 times the recommended standard; toluene is considered an item of particular concern in summer. In the correlation analysis with indoor temperature, the formaldehyde coefficient of determination was 0.4855, regarded as somewhat significant; it was difficult to confirm the correlation with temperature for the other five items, including benzene. In correlation with relative humidity, formaldehyde showed the same tendency as indoor temperature, with a coefficient of determination of 0.4404, which is believed to be due to its small molecular weight and high solubility. Due to the chimney effect, high concentrations of volatile organic compounds could be confirmed at low atmospheric pressure in the upper floors, and this trend was most evident for formaldehyde. For most items(Formaldehyde, Benzene, Toluene, Ethylbenzene, Styrene), a negative correlation was confirmed in which the emission amount decreased as the number of households increased. For large apartment houses, it is believed that it is due to sufficient bake-out and flush-out according to the adequate construction period and the use of eco-friendly and high-end building materials. Small apartments are classified together with many small houses. The emission concentration of small houses is relatively high because the proportion of the surface area where pollutants are released is high.

Analysis of Indoor Air Quality and Fresh Air Energy Consumption Based on Students’ Learning Efficiency under Different Ventilation Methods by Modelica

This paper aimed to explore a suitable ventilation method at a lower cost of energy to pursue a high learning efficiency based on the characteristics of a Chinese student group and campus building. Firstly, the model was established by Modelica and a good agreement between the numerical simulation and the results by CONTAM 3.4.0.3 was obtained. Secondly, the effects of the fixed window-opening ratio method (FWM), switch control window-opening ratio method (SCM), and automatic control window-opening ratio method (ACM) on CO2 concentration, indoor air temperature, and the heating capacity of air conditioning were investigated. The results showed that, when the FWM with 0% opening or 20% opening was adopted, the indoor CO2 concentration (ICC) was higher than the limit value of the classroom air quality standard, which was 1000 ppm. When the fixed window-opening ratio was greater than 40%, the indoor air temperature could not be controlled at the set value of 18 °C, which presented bad indoor thermal comfort. Meanwhile, when the ACM was adopted, the duration to meet good indoor thermal comfort was 57.17% higher than that of the SCM. However, both of them could maintain the average ICC below the set value in the class. Lastly, the fresh air energy consumption under different ventilation methods was compared. When the design temperature was 13.5 °C, it could be revealed that the fresh air energy consumption under the ACM, SCM, and FWM with 40% opening was 46.58%, 48.38%, and 51.26% lower than those at 18 °C. In summary, it was recommended to set the design temperature of the classroom at 13.5 °C, and the ACM was suggested as a suitable ventilation method to provide fresh air for the classroom.

A study of the impact of entrance space on indoor air quality in vernacular dwellings in desert areas during sandstorms

Alxa League, located in the western part of Inner Mongolia, China, frequently suffers from sandstorms. Such dusty conditions result in sharp increases in respirable particulate matter (PM10) concentration in outdoor and indoor environments, posing a significant health risk to local inhabitants. Vernacular dwellings in this area feature a specific floor plan that includes an entrance space to safeguard indoor air quality during sandstorms while being compatible with the local climate. This study utilises CONTAM, a multizone indoor air quality and ventilation analysis computer program, and field measurements to quantitatively evaluate the effectiveness of the entrance space in protecting indoor air quality against ambient PM10 pollution under both dusty and normal conditions. The simulation results reveal that the entrance space can effectively mitigate PM10 pollution in the middle room, lowering the average concentration from 47.0 μg/m3 to 37.5 μg/m3 during dust periods. However, PM10 pollution may increase in the entrance space, reaching an average concentration of up to 70.0 μg/m3. Experimental outcomes align with the simulated results. Given that construction activities exacerbate desertification and frequent sandstorms, the above findings help identify the optimal design strategies for energy-efficient green vernacular dwellings in the targeted desert area, promoting environmental harmony and addressing climate change challenges.

Air quality of health facilities in Spain

The present study examines indoor air pollution in health facilities, focusing on compounds from various sources, such as industrial products, healthcare activities and building materials. It assesses chemical and microbiological concentrations in two public hospitals, two public healthcare centres, and one public health laboratory in Spain. Measurements included indoor air quality, microbiological contaminants, ambient parameters and non-target analysis across ten different locations. Outdoor air quality was also assessed in the surroundings of the hospitals.The results showed that around 350 substances were tentatively identified at a high confidence level, with over 50 % of compounds classified as of high toxicological risk. Three indoor and 26 outdoor compounds were fully confirmed with standards. These confirmed substances were linked to medical, industrial and agricultural activities. Indoor Air Quality (IAQ) results revealed that CO, CO2, formaldehyde (HCHO), O3 and total volatile organic compounds (TVOCs) showed average values above the recommended guideline levels in at least one of the evaluated locations. Moreover, maximum concentrations detected for CO, HCHO, O3 and TVOCs in hospitals surpassed those previously reported in the literature. SARS-CoV-2 was detected in three air environments, corresponding to COVID-19 patient areas. Fungi and bacteria concentrations were acceptable in all assessed locations, identifying different fungi genera, such as Penicillium, Cladosporium, Aspergillus, Alternaria and Botrytis.

Comparative Analysis of Indoor Air Quality in Coal Mining Communities During Wet and Dry Seasons in the Coal Mining Belt of Kogi East, Nigeria

This study investigates the indoor air quality in coal mining communities during wet and dry seasons in the coal mining belt of Kogi East, Kogi State, Nigeria. The research was conducted at selected coal mining sites, specifically the Ika-Ogboyaga and Okaba mine sites, using a randomized sampling method. Indoor air quality data were collected from fifteen households in Ika and Odele villages within a 500-meter radius of the mining sites. Monitoring was performed using the Gasman autosampler to measure concentrations of nitrogen dioxide (NO₂), sulphur dioxide (SO₂), carbon monoxide (CO), hydrogen sulphide (H₂S), and particulate matter (PM₂.5 and PM₁₀). Data collection spanned 7 days each for the wet season (October 2022) and the dry season (February 2023), with measurements taken thrice daily. Meteorological parameters such as temperature, wind speed, wind direction, and relative humidity were also recorded. The results indicated higher pollutant concentrations during the dry season. For instance, PM₂.5 levels in Ika during the wet season were 45.3±0.25 μg/m³ (morning), 74.6±0.49 μg/m³ (afternoon), and 56.26±0.1 μg/m³ (evening), while dry season values were 48.32±1.74 μg/m³ (morning), 74.12±0.30 μg/m³ (afternoon), and 56.9±0.75 μg/m³ (evening). Similarly, PM₁₀ levels in Ika during the wet season were 73.61±1.44 μg/m³ (morning), 105.53±0.44 μg/m³ (afternoon), and 99.01±0.5 μg/m³ (evening), whereas dry season values were 75.47±0.70 μg/m³ (morning), 102.08±1.48 μg/m³ (afternoon), and 96.98±1.33 μg/m³ (evening). CO concentrations in Ika during the wet season were 4.22±0.22 ppm (morning), 6.13±0.3 ppm (afternoon), and 3.1±0.05 ppm (evening), and during the dry season, they were 5.55±1.74 ppm (morning), 8.11±1.46 ppm (afternoon), and 7.04±1.184 ppm (evening). Meteorological analysis showed that the dry season had higher wind speeds (2-4 m/s) compared to the wet season (0-2 m/s), and lower relative humidity (mean of 51.18%) compared to the wet season (mean of 77.55%). Air Quality Index (AQI) values indicated that PM₂.5 levels in both seasons were unhealthy (155.8-156.4 in the wet season and 151-200 in the dry season), while PM₁₀ levels were moderate (65.5-66.9 in the wet season and 51-100 in the dry season). CO, NO₂, and SO₂ levels generally remained within permissible limits set by the World Health Organization (WHO). Statistical analysis revealed significant seasonal variations in the concentrations of the monitored pollutants, with higher levels typically recorded during the dry season.

Comparative Analysis of Indoor Air Quality and Thermal Comfort Standards in School Buildings across New Zealand with Other OECD Countries

COVID-19 has improved awareness of the importance of appropriate indoor air quality (IAQ) in indoor spaces, particularly in classrooms where children are expected to learn. Research has shown that poor IAQ and temperature levels affect the cognitive performance of children. In this paper, we critically compare IAQ standards for New Zealand’s Designing Quality Learning Spaces (DQLS Document) against international benchmarks from the Organization for Economic Co-operation and Development (OECD) countries, including ASHRAE 62.1, CIBSE TM57, EN-15251, WHO AQGs, and Building Bulletins 99 and 101. The aim was to ascertain the robustness of New Zealand’s DQLS document, identify areas of superiority, and recommend the required improvement for appropriate IAQ and thermal comfort in classrooms. This comparison review focuses on IAQ parameters: CO2 levels, temperature, ventilation rates, room size, occupant density, and occupancy rates. The findings illuminate a slight lag in New Zealand’s DQLS standards compared to her international counterparts. For instance, while New Zealand’s standards align closely with WHO standards for IAQ concerning temperature and ventilation rates, the recommended CO2 range appears slightly inadequate (800 to 2000 ppm) along with occupancy and classroom size for effectively controlling classroom pollutant growth. This paper emphasises the need to align New Zealand’s IAQ and thermal comfort standards with optimal OECD benchmarks. The identified disparities present opportunities for improving learning spaces in terms of CO2 concentration, size of classroom, and occupant density in schools in New Zealand to meet globally recognised standards, ultimately creating a healthier and more conducive learning environment.

A numerical framework for the analysis of indoor air quality in a classroom

This paper presents a framework for applying Computational Fluid Dynamics (CFD) to study indoor air quality in a classroom environment by analysing the transport and extent of human-generated aerosol and carbon dioxide (CO2) accumulation. A methodology is outlined for identifying the appropriate amounts of exhaled aerosol and CO2 needed as boundary conditions for human breathing in CFD simulations, which is validated with in situ measurements obtained within a stale air classroom environment at matched conditions. This is crucial for quantifying the exhaled CO2 and aerosols from occupants, which is essential for designing ventilation settings that promote a healthy indoor environment. Good agreement is observed between the CFD and experiments for CO2 and aerosol concentration within the size range of 0.7-1μm. Further, we explore the impact of individual heat sources and breathing momentum flux on air stratification and aerosol dispersion. The analysis reveals that the thermal plume generated by each occupant and the momentum created from breathing are the characteristics of airflow in a stale air environment. This paper demonstrates the ability of the developed numerical model to reproduce realistic exhaled aerosol and CO2 in indoor ventilation settings, serving as a benchmark for investigating indoor air quality in the built environment.

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.

Multi-Zonal Analysis of Indoor Air Quality in a Higher Educational Building in the UK

This study focuses on the indoor air quality (IAQ) in a higher educational building, the London College in the UK. In this regard, indoor CO2 levels, as well as three contaminants with detrimental effects on human health: NO2, PM2.5, and SARS-CoV-2, are investigated. Various IAQ enhancement strategies are analyzed, including increased ventilation, background ventilation, improved airflow through opened doors, and the use of HEPA air cleaners. Results revealed that background ventilation and open doors during occupied periods reduced CO2 concentrations to around 1000 ppm. However, the effectiveness of background ventilation was influenced by outdoor conditions, such as wind speed and direction. The most effective method for reducing PM2.5 levels was installing an air cleaner alongside a commercial kitchen hood, resulting in a 15% greater reduction compared to background ventilation. To control the SARS-CoV-2 level, combining background ventilation or opening the doors with a 16,000 m3/h ventilation rate or using an air cleaner with baseline ventilation resulted in a basic reproductive number below 1. Overall, the research highlights the importance of background ventilation and open doors in enclosed spaces without operable windows for natural airflow. Additionally, the effectiveness of air purifiers in reducing particle and biological contaminant concentrations is demonstrated, providing valuable insights for improving IAQ in educational buildings.

Comparative analysis of indoor air quality in offices with different ventilation mechanisms and simulation of ventilation process utilizing system dynamics tool

Comparative analysis of indoor air quality in offices with different ventilation mechanisms and simulation of ventilation process utilizing system dynamics tool

Effect of paper filter windows on indoor exposure to particles of outdoor origin

Buildings are often located near ambient air pollution sources such as wildfire or heavy traffic areas. While windows in buildings are intermittently open for free cooling or natural ventilation, increased leakage area can lead to elevated human exposure to air pollutants of outdoor origin. The objective of this study is to investigate the effectiveness of paper filter windows in reducing exposure to outdoor air pollution and improving indoor air quality. The physical properties of paper windows as filtration media were experimentally determined, based on which multi-zone indoor air quality and ventilation analysis (CONTAM) simulations were performed for a full-scale building. The results show that the outdoor-indoor air exchange rate of a building can increase about 100% when conventional windows are replaced with paper filter windows. Even with the increased air exchange rate, the infiltration of outdoor particles into the building was reduced about 57–77% for the particle size range of 7–300 nm. These findings imply that paper windows have potential benefits for controlling both outdoor originated pollutants and indoor-generated pollutants with minimal energy inputs, especially in cities and communities impacted by urban air pollution and wildfires.

Mechanical, natural and hybrid ventilation systems in different building types: Energy and indoor air quality analysis

Ventilation is fundamental for providing good Indoor Air Quality in buildings. Nevertheless, it involves considerable energy consumption. In this paper, a co-simulation approach was applied to two case studies, a residential and an educational building, to evaluate different control strategies for hybrid ventilation systems in terms of annual energy demand and risk mitigation. The simulations were performed using TRNSYS and CONTAM and successively applying the Wells-Riley model to estimate the airborne infection risk. The analysis is performed for three climates, Venice, Rome and Helsinki. Results for the apartment show that different control strategies do not lead to significant variations in the overall heating demand for a given climate. In contrast, increasing natural ventilation hours during the cooling season produces savings in both sensible (up to 31% in Venice) and latent demand (up to 30% in Rome). Fan absorption in the heating season is reduced by 40% and 86% in Rome for the flat and classroom, respectively and by 84% in Venice for the apartment in the cooling season. Moreover, a control strategy enhancing natural ventilation is promising in reducing the infection risk. Therefore, if well-regulated through a suitable control strategy, the hybrid ventilation system seems promising in maintaining healthy indoor environments while reducing energy consumption.

Analysis of Indoor Air Quality in a Kindergarten

Abstract Today in addition to the design of structures, layout solutions, and the design of suitable materials, the modern construction industry also addresses meeting the requirements for the energy performance of a building, with which the topic of the quality of the indoor environment is fully intertwined. Comfort in the use of buildings, and especially the provision of thermal comfort, is a fundamental aspect in the design of technical equipment systems, where a properly selected system regulating the indoor environment can affect b oth t he e nergy p erformance o f t he building and the quality of the indoor environment. One of the important factors is the air quality, where the main factor that af-fects the indoor environment is the concentration of CO2, whose value affects the biological functions of the human organism. The subject of this research is an evaluation of the indoor air quality in a kindergarten because children are more sensitive to environmental influences.

Numerical analysis of indoor air quality in an open room: Effect of the outlet opening

Numerical analysis of indoor air quality in an open room: Effect of the outlet opening

Long-term analysis of indoor air quality and thermal comfort in a public school

The paper is focused on the investigation of the Indoor Air Quality (IAQ) in two classrooms from a thermal renovated school from Bucharest, related to indoor carbon dioxide (CO2), ozone (O3) concentrations or airborne particles (PM2.5), by using experimental data. The experimental campaign has been conducted over a long period (February-June 2022), allowing the study of indoor air quality under different weather data conditions. The results showed that the use of classroom ventilation is mandatory in order to reach a satisfactory degree of thermal comfort and indoor air quality and even the natural ventilation by windows opening remains a simply and useful tool to lower the indoor pollutant concentrations. However, if the target is to ensure permanent good indoor air quality in these learning spaces, a mechanical ventilation system is more adapted than the natural ventilation, due to the fact it is independent of the weather factors variation (outside temperature and wind velocity and direction).

A Comparison of Sedimentation Method and Active Sampler Analysis of Microbiological Indoor Air Quality - Case Study

Abstract The indoor air quality is of great importance for the health of people. Appropriate selection of methods, parameters and conditions for the analysis makes it possible to obtain the results that reliably reflect the actual state of affairs. The aim of this study was to compare the results of microbiological air analysis in selected rooms of the Biotechnology Center obtained using the sedimentation method and the impaction method. During the research, the SMA (for total bacteria number) and Sabouraud media (for total fungi number) were exposed to different times in sedimentation analysis and to different air volumes in the impaction method. In the case of the sedimentation method, significant differences were found in the total number of bacteria and fungi in 3 out of 7 rooms depending on the time of exposure. In the case of the impaction method, it was 4 out of 7 rooms for bacteria and 2 out of 7 for fungi, depending on the analysed volume of air. The comparison of the methods showed that 4 out of 6 rooms had higher number of microorganisms when impactor was used.

Data Analysis of Indoor Air Quality with and without HEPA Filter in Air Purifier (Study Case: East Jakarta Residential Area)

Humans in good health breathe air containing 21% oxygen 12 times per minute at rest. The number of breaths increases as people engage in activities. Humans need clean air to live. Therefore, measuring indoor and outdoor air quality is essential for a better lifestyle. Some circumstances and causes may impact the outcome in fine particulate matter PM2.5. Air purifiers and filtration systems were needed to be tested in East Jakarta, Indonesia, to improve indoor air quality. Different filter types are used to categorize air purifiers. HEPA filters have been created and enhanced as part of continual efforts to preserve clean, breathable air. Air purifiers decrease particulate matter with HEPA filters. This study aimed to determine how an air purifier's HEPA filter impacts air quality in a residential area of East Jakarta, Indonesia. This research contributes to a solution whether to use or not to use air purifiers indoors to have better air quality. The air quality in the East Jakarta residential area during the research period was shown to be directly improved from 8.88 to 10.49 mg/m3 with standard deviations of 9.01 to 10.18 mg/m3 for particulate matters when an indoor air purifier with a HEPA filter turned on in seven days.

Particulate matter in a lockdown home: evaluation, calibration, results and health risk from an IoT enabled low-cost sensor network for residential air quality monitoring

Low-cost sensor analysis of indoor air quality.