Indoor Air Quality In Environments Research Articles

Ozone Chemistry on Greasy Glass Surfaces Affects the Levels of Volatile Organic Compounds in Indoor Environments.

The chemistry of ozone (O3) on indoor surfaces leads to secondary pollution, aggravating the air quality in indoor environments. Here, we assess the heterogeneous chemistry of gaseous O3 with glass plates after being 1 month in two different kitchens where Chinese and Western styles of cooking were applied, respectively. The uptake coefficients of O3 on the authentic glass plates were measured in the dark and under UV light irradiation typical for indoor environments (320 nm < λ < 400 nm) at different relative humidities. The gas-phase product compounds formed upon reactions of O3 with the glass plates were evaluated in real time by a proton-transfer-reaction quadrupole-interface time-of-flight mass spectrometer. We observed typical aldehydes formed by the O3 reactions with the unsaturated fatty acid constituents of cooking oils. The formation of decanal, 6-methyl-5-hepten-2-one (6-MHO), and 4-oxopentanal (4-OPA) was also observed. The employed dynamic mass balance model shows that the estimated mixing ratios of hexanal, octanal, nonanal, decanal, undecanal, 6-MHO, and 4-OPA due to O3 chemistry with authentic grime-coated kitchen glass surfaces are higher in the kitchen where Chinese food was cooked compared to that where Western food was cooked. These results show that O3 chemistry on greasy glass surfaces leads to enhanced VOC levels in indoor environments.

Editorial: Indoor environmental air quality in urban areas

Editorial: Indoor environmental air quality in urban areas

Assessing multi-domain impact of IAQ and noise on productivity with portable air cleaners through physiological signals

The office environment's indoor air quality (IAQ) and noise levels are critical factors that affect productivity and overall health. However, a research gap still exists on multi-domain impact of IAQ and noise on human physiological signals. The research aims to establish a comprehensive understanding of the multi-domain impact by analyzing physiological signals such as Electroencephalogram (EEG), Electrodermal Activity (EDA), eye blinks, jaw clenching, and heart rate. 30 human subjects participated in a series of tests in various indoor environments with portable air cleaner configurations. The study incorporated four scenarios with baseline condition and two noise levels. By comparing the different scenarios, the separate and combined impacts of IAQ and noise on office productivity were assessed. Meanwhile, physiological signals were collected and analyzed alongside productivity tests, which included typing and addition tasks, to determine the relationship between IAQ, noise, and office productivity. We discovered a strong relationship between EEG power and productivity, indicating that EEG power was a valuable indicator for evaluating indoor environmental quality, especially the multi-domain effects of IAQ and noise. When using the air cleaner, the relative power in the Theta, Alpha, and Beta bands indicated increased concentration and activity levels in the brain. Additionally, the increasing number of jaw clenching suggested that participants became more anxious and nervous in noisy environments. We also found that there were no gender differences for the analysis of EEG power, providing insights for future research. These findings have implications for smart control and built environment aimed at enhancing office workers' well-being and productivity.

UVC-Mirror for effective pathogens inactivation in air ducts

Improving the air quality of indoor environments (IAQ) is of utmost importance to safeguard public health as people spend about 80–90% of their time indoor. Efficient Ultraviolet germicidal irradiation (UVGI) system represents a strategic and sustainable solution to protect from recurrent and new airborne pathogens. Here, we present a new approach to design highly efficient UVGI systems, which can be installed in existing Air Treatment Units (ATU) plants with minimal effort. The increased efficiency relies on the concept of an optical cavity, thanks to its shape and source position. The internal volume consists of a highly reflective cavity illuminated with UV-C lamps. Optical simulations permitted the variation of the parameters to maximize the internal irradiance and, thus, the performance. The sanitation efficacy of the system was assessed on a full-scale pilot system. Tests were carried out under normal operating conditions against various microorganisms showed an inactivation rate of &gt; 99%. The benefits of such systems are triple and encompass economic, environmental, and societal aspects. Since the system requires little energy to operate, its application for air disinfection may yield significant energy savings and ensure a balance between energy sustainability and good IAQ.

Mitigating Indoor Air Pollution in University Dormitory: The Need for Better Ventilation and Resident Awareness

Due to the expansion of the education industry in Dubai, universities have built many dormitories. Even though Dubai has a robust indoor air quality (IAQ) stipulation for public and educational buildings, dormitories must be included. IAQ in newly constructed university dormitories can be significantly influenced by emissions from furniture made from materials such as plywood, medium-density fiberboard (MDF), or particle board (PB) that contains formaldehyde (HCHO). This study aimed to investigate and improve the IAQ in a newly constructed university dormitory. As a methodology, the study measured the concentrations of total volatile organic compound (TVOC) and HCHO in three identical rooms on different floors of a newly constructed dormitory. The experiment results showed that TVOC and HCHO were generally high, ranging from 0.23 to 18.4 ppm, up to two months after in the new dormitory, but they tended to decrease over time. The two primary factors contributing to the decrease in these pollutants were increased ventilation and reduced occupancy. Comparing the three rooms provided valuable insights into the factors influencing indoor air quality, such as the amount of infiltration through the window gaps, cooling temperatures, and humidity. The study suggests that the air quality in indoor environments can be improved by increasing ventilation, reducing occupancy, and managing the use of household items that emit pollutants. The findings can inform strategies to enhance building IAQ, promoting occupant health and well-being. From these findings, TVOC concentrations in room 1A decreased from 6.57 ppm at the first measurement to 0.13 ppm at the third measurement, while room 3B showed a decrease from 18.4 ppm to 1.16 ppm, and room 5C showed a decrease from 12.5 ppm to 0.93 ppm. HCHO concentrations also decreased, with room 1A decreasing from 2.56 ppm to 0.22 ppm, room 3B decreasing from 4.50 ppm to 2.82 ppm, and room 5C decreasing from 6.88 ppm to 2.15 ppm over the same period.

Use of Arduino for Monitoring the Air Quality of Indoor Environments

In this work, a prototype was developed to assess indoor air quality using an Arduino system. The system is based on the measurement of the light level, smoke concentration, temperature and air humidity. A thermal comfort index (TCI) was proposed, where a scale from 0 to 1 based on the weighted average of the individual indices was developed. Another approach, based on artificial neural networks, was formulated in which the parameters were used as input arguments of the network and the TCI was used as a target parameter. The response of the two models was compared, where it was possible to observe that the TCI values calculated by the network were considerably close to the values obtained by the deterministic model, with MSE of 1.73?10-5.

Field measurements of indoor and community air quality in rural Beijing before, during, and after the COVID-19 lockdown.

The coronavirus (COVID‐19) lockdown in China is thought to have reduced air pollution emissions due to reduced human mobility and economic activities. Few studies have assessed the impacts of COVID‐19 on community and indoor air quality in environments with diverse socioeconomic and household energy use patterns. The main goal of this study was to evaluate whether indoor and community air pollution differed before, during, and after the COVID‐19 lockdown in homes with different energy use patterns. Using calibrated real‐time PM2.5 sensors, we measured indoor and community air quality in 147 homes from 30 villages in Beijing over 4 months including periods before, during, and after the COVID‐19 lockdown. Community pollution was higher during the lockdown (61 ± 47 μg/m3) compared with before (45 ± 35 μg/m3, p < 0.001) and after (47 ± 37 μg/m3, p < 0.001) the lockdown. However, we did not observe significantly increased indoor PM2.5 during the COVID‐19 lockdown. Indoor‐generated PM2.5 in homes using clean energy for heating without smokers was the lowest compared with those using solid fuel with/without smokers, implying air pollutant emissions are reduced in homes using clean energy. Indoor air quality may not have been impacted by the COVID‐19 lockdown in rural settings in China and appeared to be more impacted by the household energy choice and indoor smoking than the COVID‐19 lockdown. As clean energy transitions occurred in rural households in northern China, our work highlights the importance of understanding multiple possible indoor sources to interpret the impacts of interventions, intended or otherwise.

Can data reliability of low-cost sensor devices for indoor air particulate matter monitoring be improved? – An approach using machine learning

Poor indoor air quality has adverse health impacts. Children are considered a risk group, and they spend a significant time indoors at home and in schools. Air quality monitoring has traditionally been limited due to the cost and size of the monitoring stations. Recent advancements in low-cost sensors technology allow for economical, scalable and real-time monitoring, which is especially helpful in monitoring air quality in indoor environments, as they are prone to sudden peaks in pollutant concentrations. However, data reliability is still a considerable challenge to overcome in low-cost sensors technology. Thus, following a monitoring campaign in a nursery and primary school in Porto urban area, the present study analyzed the performance of three commercially available low-cost IoT devices for indoor air quality monitoring in real-world against a research-grade device used as a reference and developed regression models to improve their reliability. This paper also presents the developed on-field calibration models via machine learning technique using multiple linear regression, support vector regression, and gradient boosting regression algorithms and focuses on particulate matter (PM1, PM2.5, PM10) data collected by the devices. The performance evaluation results showed poor detection of particulates in classrooms by the low-cost devices compared to the reference. The on-field calibration algorithms showed a considerable improvement in all three devices' accuracy (reaching up to R2 > 0.9) for the light scattering technology based particulate matter sensors. The results also show the different performance of low-cost devices in the lunchroom compared to the classrooms of the same school building, indicating the need for calibration in different microenvironments.

Prevention of pathogen microorganisms at indoor air ventilation system using synthesized copper nanoparticles.

This article describes the impregnation of copper nanoparticles (CuNP) in a polyester fibre filter that can be used in solid–gas filtration to retain the spread of pathogen microorganisms in indoor environments. The impregnation of the CuNP was achieved by spraying the suspension on the surface of filter media. An acid pretreatment was also evaluated to increase the adhesion between fibre and nanoparticle. The synthesis of the CuNP was done by chemical reduction. The bacterial effect was measured through the contact method for Escherichia coli and Staphylococcus aureus, and we demonstrate that the presence of CuNP to filter media reduced up to 99.99% of gram‐negative and 99.98% of gram‐positive bacteria. The pretreatment with HCl was a good alternative to filter modification due to the higher adhesion between CuNP and the fibre while the high efficiency against pathogen microorganisms was kept. The modification of filters with CuNP can improve the air quality of indoor environments, vanishing the pathogen microorganisms circulating in the air.

Stereoscopic particle image velocimetry study of the single side entrainment behaviour of multiple air jets with different nozzle cross-sections

Achieving energy savings in the building sector while maintaining high air quality of indoor environments requires efficient ventilation systems. Active chilled beams (ACBs) are a promising solution for the ventilation in non-residential buildings. Their functionality is often based on the single side entrainment of multiple air jets. In order to enhance this entrainment and thus increase the efficiency of ACBs, this study investigates the specific flow situation of a single side entrainment experimentally. Additionally to the reference circular type, three different cross-sections (elliptic, cross-like, lobed) of an orifice nozzle are investigated with different experimental methods. The unique flow situation in ACBs with multiple interacting jets entraining air from one side is extracted to a test bench. First, the general nozzle efficiency and total entrainment is investigated. Then, the detailed understanding of the entrainment process is achieved with stereoscopic particle image velocimetry (stereo-PIV). The results show that a minimum distance between the jets is necessary for the development of individual flow behaviour affecting the entrainment. For a larger nozzle distance we measured an increased overall entrainment for the non-circular nozzle geometries, with the lobed geometry showing the greatest improvement. The PIV results show how the jets from the different nozzle geometries pass through different stages of entrainment behaviour and profile transformation.

A review on reducing indoor particulate matter concentrations from personal-level air filtration intervention under real-world exposure situations.

Improving air quality in indoor environments where people live is of importance to protect human health. In this systematic review, we assessed the effectiveness of personal-level use of air filtration units in reducing indoor particulate matters (PM) concentrations under real-world situations following systematic review guidelines. A total of 54 articles were included in the review, in which 20 randomized controlled/crossover trials that reported the changes in indoor fine PM (PM2.5 ) concentrations were quantitatively assessed in meta-analysis. Standardized mean differences (SMDs) were calculated for changes in indoor PM concentrations following air filtration interventions. Moderate-to-large reductions of 11%-82% in indoor PM2.5 concentrations were observed with SMD of -1.19 (95% CI: -1.50, -0.88). The reductions in indoor PM concentrations varied by geographical locations, filtration technology employed, indoor environmental characteristics, and air pollution sources. Most studies were graded with low-to-moderate risk of bias; however, the overall certainty of evidence for indoor PM concentration reductions was graded at very low level. Considering the effectiveness of indoor air filtration under practical uses, socio-economic disparities across study populations, and costs of air filter replacement over time, our results highlight the importance of reducing air pollution exposure at the sources.

Adoption of Green Building Assessment Systems to Existing Buildings under Kazakhstani Conditions

The construction industry is an enormous economic sector with a profound economic, social, and environmental impact. The building sector is responsible for one-third of total energy consumption and, notably, construction activities account for 39% of the total carbon emissions in the world. Therefore, nowadays, the promotion of green building concepts is essential for all countries. Typically, the sustainability level of a building is evaluated by specified certification systems through rating assessment tools. The development of national assessment tools is necessary for the developing world due to environmental, social, and economic issues; consequently, a national assessment tool adopted under specific local conditions would provide a more precise assessment. This paper analyzes the rating system of BREEAM, LEED, CASBEE, and Green Globes certification systems and discusses their adoption with assessment measures for the existing buildings in Kazakhstan’s reality. The following main criteria were discussed during six roundtable sessions: sustainable site and landscape, energy and carbon footprint reduction, water and wastewater management, indoor environmental quality, sustainable building materials, commissioning, and maintenance. A set of assessment criteria and measures were suggested, and 43 existing buildings were assessed. Only eight buildings reached a high rating level. The “sustainable site and landscape” and “indoor environmental air quality” categories were the categories with the highest scores; otherwise, “energy and carbon footprint reduction” with “water and wastewater management” had the lowest average scores. One of the buildings was evaluated separately by several experts to check the consistency of the suggested assessment measures. This evaluation also provided insight into how the assessors’ knowledge and experience may change the overall rating scores obtained. The most critical issues for the existing buildings in Kazakhstan’s reality were discussed. Despite the widespread adoption of green certification methodology, the application of global certification systems in Kazakhstan remains complicated due to the lack of knowledge and limited awareness.

In-flight particulate matter concentrations in commercial flights are likely lower than other indoor environments.

Air quality in indoor environments can have significant impacts on people's health, comfort, and productivity. Particulate matter (PM; also referred to as aerosols) is an important type of air pollutant, and exposure to outdoor PM has been associated with a variety of diseases. In addition, there is increasing recognition and concern of airborne transmission of viruses, including severe acute respiratory syndrome corona-virus 2 (SARS-CoV-2), especially in indoor environments. Despite its importance, indoor PM data during the COVID-19 pandemic are scarce. In this work, we measured and compared particle number and mass concentrations in aircraft cabins during commercial flights with various indoor environments in Atlanta, GA, during July 2020, including retail stores, grocery stores, restaurants, offices, transportation, and homes. Restaurants had the highest particle number and mass concentrations, dominated by cooking emissions, while in-flight aircraft cabins had the lowest observed concentrations out of all surveyed spaces.

A Novel Insight into the Ozone-Skin Lipid Oxidation Products Observed by Secondary Electrospray Ionization High-Resolution Mass Spectrometry.

Emissions of secondary products through reactions of oxidants, ozone (O3), and hydroxyl radical (·OH) with human skin lipids have become increasingly important in indoor environments. Here, we evaluate the secondary organic compounds formed through heterogeneous reactions of gaseous O3 with hand skin lipids by using a high-resolution quadrupole Orbitrap mass spectrometer coupled to a commercial secondary electrospray ionization (SESI) source. More than 600 ions were detected over a period of less than 40 min real-time measurements, among which 53 ions were characterized with a significant increasing trend in signal intensity at the presence of O3. Based on the detected ions, we suggest detailed reaction pathways initiated by ozone oxidation of squalene that results in primary and secondary ozonides; we noticed for the first time that these products may be further cleaved by direct reaction of nucleophilic ammonia (NH3), emitted from human skin. Finally, we estimate the fate of secondarily formed carbonyl compounds with respect to their gas-phase reactions with ·OH, O3, and NO3 and compared with their removal by air exchange rate (AER) with outdoors. The obtained results suggest that human presence is a source of an important number of organic compounds, which can significantly influence the air quality in indoor environments.

Indoor and outdoor concentrations of benzene, toluene, ethylbenzene and xylene in some Italian schools evaluation of areas with different air pollution

The air quality of indoor environments is an aspect of great importance and of growing interest, particularly considering the length of time that people stay in confined spaces. The objective of this study was to study the indoor and outdoor concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) in 8 Italian schools, many of which are located in some of the most highly polluted areas in Italy. This wanted to provide useful information for understanding the status of air quality in sensitive indoor and outdoor areas (schools) and to support the development of recommendations and indications useful to territorial administrations in the improvement of environmental quality strategies. The sampling campaigns were performed with passive samplers from 2014 to 2015, studying both the hot and cold seasons. A common sampling and analytical protocol was applied in all the study areas. Passive sampler data were also compared with BTEX measurements from fixed-site monitoring stations selected as references for each school. Our findings showed the prevalence of low BTEX concentrations with relatively high values limited to toluene, ethylbenzene and xylene in a few monitoring sites and periods. The mean concentration values of benzene, toluene, ethylbenzene and xylene varied from 0.10 μg/m3 to 10.75 μg/m3, from 0.10 μg/m3 to 28.18 μg/m3, from 0.10 μg/m3 to 11.1 μg/m3 and from 0.10 μg/m3 to 14.45 μg/m3, respectively. In indoor environments, the concentrations were equal to or higher than the values measured outdoors in most cases, frequently reporting I/O ratios greater than 1.

Influence of operating parameters on the single-pass photocatalytic removal efficiency of acrylonitrile

Photocatalytic oxidation (PCO) is an advanced air cleaning technology that is used as a means to improve air quality in indoor environments and could also potentially be used in hospital operating rooms (ORs). However, when it comes to the feasibility of using PCO to remove VOCs, most studies have been on those that are commonly found in indoor environments like homes and schools. There are little or no studies on other indoor environments like hospitals. Therefore in this work, acrylonitrile, one of the hazardous compounds found in surgical smoke (a source of pollution in the OR) was chosen as a representative compound to evaluate the performance of a photocatalytic system in an OR. The experiments were performed in a 420-L multi-pass laboratory reactor. The performance of the system was based on the influence that three operating parameters (air velocity, light intensity and initial concentration) would have on the single-pass removal efficiency (SPRE). A mathematical model was used to enable the calculation of the SPRE from the experimental degradation profile. The influence of the operating parameters on the degradation of acrylonitrile as well as the possible intermediates formed and mineralization rates are discussed.

Integration of a photocatalytic multi-tube reactor for indoor air purification in HVAC systems: a feasibility study.

This work is focused on an in-depth experimental characterization of multi-tube reactors for indoor air purification integrated in ventilation systems. Glass tubes were selected as an excellent photocatalyst substrate to meet the challenging requirements of the operating conditions in a ventilation system in which high flow rates are typical. Glass tubes show a low-pressure drop which reduces the energy demand of the ventilator, and additionally, they provide a large exposed surface area to allow interaction between indoor air contaminants and the photocatalyst. Furthermore, the performance of a range of P25-loaded sol-gel coatings was investigated, based on their adhesion properties and photocatalytic activities. Moreover, the UV light transmission and photocatalytic reactor performance under various operating conditions were studied. These results provide vital insights for the further development and scaling up of multi-tube reactors in ventilation systems which can provide a better comfort, improved air quality in indoor environments, and reduced human exposure to harmful pollutants.

Indoor Air Mycological Survey and Occupational Exposure in Libraries in Mato Grosso-Central Region—Brazil

Background: Indoor air quality in environments where there is great circulation of people, posing risks to the health of its occupants, including allergic problems, infections and contaminations, can be aided by climatic factors, chemicals and biological agents housed in these environments, influencing the location and providing favorable conditions for the degradation of bibliographic collections. The present study investigated the presence of fungi in indoor environments in seven public and private libraries in the central region of Brazil, Mato Grosso, and verified the impact on occupational health. Results: A total of 26,194 fungal specimens were isolated from 342 dust samples collected using three techniques: Andersen’s sampler (12.3%), exposure plate dish (25.1%) and sterile swab (62.6%). A total of 184 fungal species were identified: 156 (84.8%) mycelial fungi and 28 (15.2%) yeast fungi, belonging 54 fungal genera, 43 (79.6%) mycelial fungi and 11 (20.4%) yeast fungi. The genus Aspergillus (40.6%) was one of the main fungi present in indoor air. Aspergillus niger (12.3%) was identified as the most prevalent species in literary environments, followed by Cryptococcus spp. (7.1%) and Cladosporium cladosporioides (7.0%). In relation to seasonal distribution, there was a greater fungal isolation in the dry season (54%); followed by the rainy season (46%). Conclusion: These results suggest the substrates researched in the evaluated environments presented in the form of documents, books and papers associated with dust and air humidity become suitable for microbiological proliferation. These findings highlight the importance of minimizing the risk of exposure to fungal agents, identified in pathogenic and toxigenic microenvironments in library collections.

DALY indicator as an assessment tool for indoor air quality impact on human health

The quality of indoor environment is an extremely important issue, because people spend large parts of the day inside buildings. The quality of the indoor environment is largely dependent on the quality of indoor air. The parameters of the air we breathe affect our health and comfort of room use. Currently, when energy efficiency is a priority, it is difficult to maintain comfort and conditions appropriate for human health. The artificial environment in a room and related inadequate air quality cause many diseases, such as asthma, lung diseases, cardiovascular diseases, as well as poor well-being and reduced productivity. The Disability Adjusted Life Years (DALY) indicator means “loss of life corrected by disability” and is widely used by the World Health Organization to measure a disease burden on the population and identify the causes of a disease. The aim of the article is to present the structure of the DALY indicator and its suitability to assess the impact of indoor air quality on human health. The most frequent diseases caused by low quality of internal air were analysed based on statistical data. In addition, the possibilities of ventilation solutions have been presented, leading to the improvement of air quality in indoor environment.

The concept of thin film bulk acoustic resonators as selective CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; gas sensors

Abstract. Carbon dioxide (CO2) is a gas that well represents air quality in indoor environments as well as being an important greenhouse gas. However, the reliable and affordable sensing of environmental CO2 at room temperature, with techniques other than optical spectroscopy, remains an unsolved problem to this day. One major challenge for solid state sensors is the realisation of adequate selectivity, especially towards changing humidity. The thin film bulk acoustic resonator (FBAR) is a MEMS (Microelectromechanical systems) device that can not only detect gas-induced mass changes but also changes in the acoustic velocity and density of its layers. This multi-sensing provides a suitable platform for selective gas sensing. In this work we present studies done on polyaminosiloxane- and ethyl cellulose-functionalised FBARs regarding CO2 sensitivity, selectivity towards humidity, and stability. We demonstrate how CO2 and humidity signals can be separated and that CO2 can be sensed with a resolution of 50 ppm between 400 and 1000 ppm. Using the Mason model, we show how the acoustic velocity and density of an absorption layer can be determined and how changes in those parameters affect the resonance frequency shift. The understanding of these results ultimately presents a tool to theoretically separate any number of gas analytes.