Indoor Air Quality Guidelines Research Articles

Impact of Indoor Air Quality on Student Health in Closed Classroom Environments

This research explores the impact of Indoor Air Quality (IAQ) on students' well-being in crowded classrooms, emphasizing the necessity of optimal air quality for a conducive learning environment. It raises concerns about the public health implications of poor IAQ, particularly in densely populated and inadequately ventilated schools. The study examines the effects of various pollutants, such as PM10, PM2.5, SO2, and NO2, on students' respiratory health and cognitive function. Findings indicate that exposure to these pollutants can lead to respiratory diseases, diminished cognitive abilities, and increased absenteeism, ultimately affecting academic performance. The research underscores the importance of accurate air quality monitoring and implementing preventive measures to safeguard students' health. Educational institutions can create safer and healthier learning environments by adhering to IAQ guidelines and integrating advanced sensor technologies and real-time monitoring systems. This study highlights the critical role of maintaining good IAQ in enhancing students' overall quality of life and academic success, advocating for the convergence of science, technology, and policy to optimize indoor air quality in schools.

Numerical analysis on mechanical ventilation impact on indoor air quality in a basement

Indoor air quality (IAQ) in confined spaces like bank vaults and basements is influenced by complex factors such as building layout and HVAC systems. This study examines how mechanical ventilation impacts IAQ in a bank building's occupied basement vault, addressing significant challenges posed by pollutant exposure in these air-tight environments. This study advances safe IAQ in confined spaces, crucial for occupant health and safety, using CFD (ANSYS Fluent Workbench 16.0) and CONTAM 3.2 software for multi-zone ventilation and air quality analysis. It analysed three indoor pollutants: Radon (Rn), Carbon dioxide (CO2), and Particulate Matter (PM2.5), enhancing the reliability and applicability of the findings. The findings indicated that the simulated indoor pollutants concentrations did not exceed the indoor air quality guideline levels. The CFD simulations predicted average steady-state values of 27.2 Bq/m3 for Radon, 574.80 ppm for CO2, and 69.36 µg/m3 for PM2.5 in the basement. For different outdoor air floor rates, an optimal ventilation rate of 4.7 ACH and a cooling load of 17 kW were determined to maintain Radon concentrations below 15 Bq/m3. This provides a practical and actionable solution for maintaining safe IAQ in confined spaces, which is a significant step forward compared to similar studies. These results align with other experimental research, validating the use of numerical techniques in indoor air quality studies. By optimizing HVAC systems to maintain IAQ and minimize energy consumption, the study supports SDG 7 (Affordable and Clean Energy) by enhancing energy efficiency, SDG 3 (Good Health and Well-being) by reducing exposure to indoor pollutants, and SDG 11 (Sustainable Cities and Communities) by improving air quality management in confined spaces. The findings are particularly relevant for Africa, offering practical solutions, informing policy direction, and supporting the African Union's Agenda 2063 and SDGs 3, 7, and 11.

Characterising indoor air quality in private vehicle cabins under unprecedented traffic conditions during COVID-19 lockdown

Air pollution negatively impacts human health, yet it is rarely studied inside vehicles. This study aimed to characterise indoor air quality (IAQ) in vehicle cabins, focusing on the concentrations of key pollutants and the influence of various factors on IAQ including vehicle-specific characteristics (self-pollution), traffic intensity, ventilation type, and enclosed spaces like parking garages. It addressed a significant literature gap by using real-world driving data, a multipollutant approach, real-time monitoring, and a detailed log of influencing factors. Additionally, part of the study was conducted during the COVID-19 lockdown, providing an unprecedented opportunity to gather real-world data with reduced traffic emissions. Forty trips were conducted with four diesel vehicles of different ages and emission standards. Concentrations of VOCs, CO, CO₂, NO₂, SO₂, O₃, and PM₁, PM₂.₅, PM₁₀, and TSP were monitored, alongside detailed logbook entries. This study evidenced the formation of O₃ inside vehicle cabins under conditions of high NO₂ and/or VOC concentrations and direct sunlight, a phenomenon not previously reported. Results also showed that IAQ inside vehicle cabins depended largely on vehicle-specific factors, the surrounding environment, and indoor-outdoor air exchange. CO, NO₂, SO₂, and PM levels varied mainly with the external environment and air exchange, while CO₂ levels were influenced primarily by ventilation settings. The concentrations of certain pollutants exceeded reference levels for indoor environments, potentially posing health risks to occupants. Further research is needed to study the pioneer evidence of O3 formation and to develop a comprehensive health risk assessment, thereby contributing to developing specific IAQ guidelines for vehicles.

Carbon dioxide guidelines for indoor air quality: a review.

The importance of building ventilation to protect health has been more widely recognized since the COVID-19 pandemic. Outdoor air ventilation in buildings dilutes indoor-generated air pollutants (including bioaerosols) and reduces resulting occupant exposures. Many countries and organizations have advisory guidelines or mandatory standards for minimum ventilation rates (VRs) to maintain indoor air quality (IAQ). Because directly measuring VRs is often difficult, many IAQ guidelines instead specify indoor concentration limits for carbon dioxide (CO2), using CO2 exhaled by building occupants as an indicator of VR. Although indoor CO2 guidelines are common, the evidence basis for the various CO2 limits has not been clear. To review current indoor CO2 guidelines worldwide and the supportive evidence provided. We identified worldwide CO2-based guidelines for IAQ or ventilation, along with any supportive evidence provided. We excluded occupational guidelines for CO2 levels ≥5000 ppm. Among 43 guidelines identified, 35 set single CO2 concentration limits and eight set multi-tiered limits; 16 mentioned no specific human effect to be controlled, 19 specified only odor dissatisfaction, five specified non-infectious health effects, and three specified airborne infectious disease transmission. The most common indoor CO2 limit was 1000 ppm. Thirteen guidelines specified maximum CO2 limits as extended time-weighted averages, none with evidence linking averaged limits to occupant effects. Of only 18 guidelines citing evidence to support limits set, we found this evidence persuasive for eight. Among these eight guidelines, seven set limits to control odor perception. One provided 17 scientifically-based CO2 limits, for specific example space uses and occupancies, to control long-range COVID-19 transmission indoors. Many current indoor carbon dioxide (CO2) guidelines for indoor air quality specified no adverse effects intended for control. Odor dissatisfaction was the effect mentioned most frequently, few mentioned health, and three mentioned control of infectious disease. Only one CO2 guideline was developed from scientific models to control airborne transmission of COVID-19. Most guidelines provided no supportive evidence for specified limits; few provided persuasive evidence. No scientific basis is apparent for setting one CO2 limit for IAQ across all buildings, setting a CO2 limit for IAQ as an extended time-weighted average, or using any arbitraryone-time CO2 measurement to verify a desired VR.

Optimizing Indoor Air Quality to mitigate Sick Building Syndrome

- In current scenario, where individuals spend the majority of their time indoors, the quality of the indoor air has become increasingly crucial. This research paper investigates the role of optimizing Indoor Air Quality (IAQ) as a proactive strategy for mitigating Sick Building Syndrome (SBS) within built environments. It examines the relationship between indoor air quality (IAQ) and Sick Building Syndrome (SBS) in workplace settings and explores strategies for enhancing IAQ to mitigate SBS symptoms. Indoor air quality (IAQ) significantly impacts human health and well-being, with implications for productivity, comfort, and overall quality of life. To ensure safe and healthy indoor environments, various organizations, including the World Health Organization (WHO), Environmental Protection Agency (EPA), and Occupational Safety and Health Administration (OSHA), have established IAQ standards and guidelines. This research aims to conduct a comprehensive analysis of these standards. Moreover, the multifaceted nature of IAQ management is explored through the inclusion of parameters like radon (Rn), relative humidity (RH), and temperature. These factors not only contribute to indoor air quality but also affect occupants' comfort and well-being. By considering both chemical and environmental factors. Key Words: Indoor air quality, mitigate, policies, Sick building syndrome

Indoor Air Quality (IAQ) Management in Hong Kong: The Way Forward

There has been an increasing awareness of indoor air quality (IAQ) management in green building designs, driven by the need to mitigate potential health risks and create sustainable and healthy indoor environments. The COVID-19 pandemic has further highlighted the critical role of ventilation and IAQ in reducing the risk of indoor airborne transmission. Governments and organisations worldwide have responded to this growing concern by implementing ventilation requirements and updating IAQ standards and guidelines. In the case of Hong Kong, a developed and densely populated city characterised by high-rise buildings, this study aims to provide a strategic framework for non-governmental agencies to address IAQ issues effectively. A comprehensive review of policies, regulations, and guidelines by international bodies and individual governments, along with an examination of the current IAQ management scheme in Hong Kong, has been conducted. Drawing inspiration from successful IAQ management strategies, the study aims to identify insights and potential pathways for the city’s future development of IAQ management strategies. Overall, this research highlights the importance of proactive IAQ management for buildings and offers a roadmap for Hong Kong’s pursuit of healthier indoor environments.

Impact of indoor air pollution exposure from traditional stoves on lung functions in adult women of a rural Indian district

Introduction: Biomass Fuels (BMF) used for daily cooking in developing countries inside home is the highest exposures to air pollutants. Inhalation of these pollutants causes harmful health effects. This study aims to assess the health effects with the indoor air pollutants generated BMF.
 Materials and methods: A cross-sectional study, conducted in a rural village of India. 450 households were divided into two groups based on the cooking fuel, the BMF group and the Liquefied Petroleum Gas (LPG) clean fuel group. Socioeconomic and respiratory symptoms information was obtained using a standard questionnaire. Indoor air concentration for PM10 and PM2.5 was measured during cooking hours. Pulmonary Function Tests (PFTs) were conducted for the women inhabitants using spirometer.
 Results: Respiratory symptoms like chest pain, breathlessness, eye irritation, and blackout found to be significantly higher in biomass users (P<0.05). Moreover, an increasing trend in the prevalence of symptoms/ morbid conditions observed with an increase in exposure.
 Conclusion: Findings of the study confirms that the traditional use of biomass fuels exposes all family members daily to air pollution levels that well exceed available health guidelines for indoor air quality and highlights the critical gender and age dimensions of the Household Air Pollution (HAP) problem. Women exposed to BMF smoke suffer more from health problems and are at higher risk of respiratory illnesses than other fuel users.

Exposure limits for indoor volatile substances concerning the general population: The role of population-based differences in sensory irritation of the eyes and airways for assessment factors.

Assessment factors (AFs) are essential in the derivation of occupational exposure limits (OELs) and indoor air quality guidelines. The factors shall accommodate differences in sensitivity between subgroups, i.e., workers, healthy and sick people, and occupational exposure versus life-long exposure for the general population. Derivation of AFs itself is based on empirical knowledge from human and animal exposure studies with immanent uncertainty in the empirical evidence due to knowledge gaps and experimental reliability. Sensory irritation in the eyes and airways constitute about 30-40% of OELs and is an abundant symptom in non-industrial buildings characterizing the indoor air quality and general health. Intraspecies differences between subgroups of the general population should be quantified for the proposal of more 'empirical' based AFs. In this review, we focus on sensitivity differences in sensory irritation about gender, age, health status, and vulnerability in people, based solely on human exposure studies. Females are more sensitive to sensory irritation than males for few volatile substances. Older people appear less sensitive than younger ones. However, impaired defense mechanisms may increase vulnerability in the long term. Empirical evidence of sensory irritation in children is rare and limited to children down to the age of six years. Studies of the nervous system in children compared to adults suggest a higher sensitivity in children; however, some defense mechanisms are more efficient in children than in adults. Usually, exposure studies are performed with healthy subjects. Exposure studies with sick people are not representative due to the deselection of subjects with moderate or severe eye or airway diseases, which likely underestimates the sensitivity of the group of people with diseases. Psychological characterization like personality factors shows that concentrations of volatile substances far below their sensory irritation thresholds may influence the sensitivity, in part biased by odor perception. Thus, the protection of people with extreme personality traits is not feasible by an AF and other mitigation strategies are required. The available empirical evidence comprising age, lifestyle, and health supports an AF of not greater than up to 2 for sensory irritation. Further, general AFs are discouraged for derivation, rather substance-specific derivation of AFs is recommended based on the risk assessment of empirical data, deposition in the airways depending on the substance's water solubility and compensating for knowledge and experimental gaps. Modeling of sensory irritation would be a better 'empirical' starting point for derivation of AFs for children, older, and sick people, as human exposure studies are not possible (due to ethical reasons) or not generalizable (due to self-selection). Dedicated AFs may be derived for environments where dry air, high room temperature, and visually demanding tasks aggravate the eyes or airways than for places in which the workload is balanced, while indoor playgrounds might need other AFs due to physical workload and affected groups of the general population.

Simultaneous Analysis of Insecticides and Phthalates in Residential Buildings Based on Japan’s Indoor Air Quality Guidelines

Simultaneous Analysis of Insecticides and Phthalates in Residential Buildings Based on Japan’s Indoor Air Quality Guidelines

Changes in Concentration of Carbon Dioxide and Temperature in University Classrooms

This study aims to observe variations in temperature, relative humidity, and carbon dioxide concentrations in university classrooms without mechanical ventilation throughout the day. Over three days, two classrooms in Riga Stradiņš University, equipped solely with natural ventilation, were evaluated for variations in indoor air quality. Observations were recorded using the Aranet4 sensor during actual study sessions with varying numbers of occupants, and ventilation periods marked by window operations. The recorded parameters were compared with established indoor air quality guidelines. The results showed that the relative humidity remained within the ideal range (40%-60%) throughout the observation period. Indoor temperature varied between 18 °C to 26 °C, with noticeable increases during practical study sessions and decreases during ventilation periods. The carbon dioxide levels consistently exceeded the safe limit of 1000 ppm during all study sessions, with the time taken to exceed this threshold being directly proportional to the number of occupants. The findings underline the need for strategic ventilation interventions and classroom arrangements, considering occupancy and room size to promote healthier learning environments. Further research incorporating occupant surveys and including diverse educational settings is recommended. Keywords: indoor air quality; natural ventilation; classroom environment; carbon dioxide; relative humidity; temperature.

Beyond the outdoors: indoor air quality guidelines and standards- challenges, inequalities, and the path forward.

In the last few decades, indoor air quality (IAQ) has become a major threat to public health. It is the fifth leading cause of premature death globally. It has been estimated that people spend ∼90 % of their time in an indoor environment. Consequently, IAQ has significant health effects. Although IAQ-related standards and guidelines, policies, and monitoring plans have been developed in a few countries, there remain several global inequalities and challenges. This review paper aims to comprehensively synthesize the current status of widely accepted IAQ guidelines and standards. It analyzes their global implementation and effectiveness to offer insights into challenges and disparities in IAQ policies and practices. However, the complexity of domestic environments and the diversity of international standards impede effective implementation. This manuscript evaluates international, national, and regional IAQ guidelines, emphasizing similarities and differences. In addition, it highlights knowledge gaps and challenges, urging the international scientific community, policymakers, and stakeholders to collaborate to advance IAQ standards and guidelines. The analysis evaluates the efficacy of guidelines, identifies deficiencies, and offers recommendations for the future of domestic air quality standards.

Kitchen fine particulate matter (PM2.5) concentrations from biomass fuel use in rural households of Northwest Ethiopia.

Combustion of solid biomass fuels using traditional stoves which is the daily routine for 3 billion people emits various air pollutants including fine particulate matter which is one of the widely recognized risk factors for various cardiorespiratory and other health problems. But, there is only limited evidences of kitchen PM2.5 concentrations in rural Ethiopia. This study is aimed to estimate the 24-h average kitchen area concentrations of PM2.5 and to identify associated factors in rural households of northwest Ethiopia. The average kitchen area PM2.5 concentrations were measured using a low-cost light-scattering Particle and Temperature Sensor Plus (PATS+) for a 24-h sampling period. Data from the PATS+ was downloaded in electronic form for further analysis. Other characteristics were collected using face-to-face interviews. Independent sample t-test and one-way analysis of variance were used to test differences in PM2.5 concentrations between and among various characteristics, respectively. Mixed fuels were the most common cooking biomass fuel. The 24-h average kitchen PM2.5 concentrations was estimated to be 405 μg/m3, ranging from 52 to 965 μg/m3. The average concentrations were 639 vs. 336 μg/m3 (p < 0.001) in the thatched and corrugated iron sheet roof kitchens, respectively. The average concentration was also higher among mixed fuel users at 493 vs. 347 μg/m3 (p = 0.042) compared with firewood users and 493 vs. 233 μg/m3 (p = 0.007) as compared with crop residue fuel users. Statistically significant differences were also observed across starter fuel types 613 vs. 343 μg/m3 (p = 0.016) for kerosene vs. dried leaves and Injera baking events 523 vs. 343 μg/m3 (p < 0.001) for baked vs. not baked events. The average kitchen PM2.5 concentrations in the study area exceeded the world health organization indoor air quality guideline value of 15 μg/m3 which can put pregnant women at greater risk and contribute to poor pregnancy outcomes. Thatched roof kitchen, mixed cooking fuel, kerosene fire starter, and Injera baking events were positively associated with high-level average kitchen PM2.5. concentration. Simple cost-effective interventions like the use of chimney-fitted improved stoves and sensitizing women about factors that aggravate kitchen PM2.5 concentrations could reduce kitchen PM 2.5 levels in the future.

Evaluation of ventilation in Australian school classrooms using long-term indoor CO2 concentration measurements

School classrooms are often reported as having insufficient ventilation with elevated indoor CO2 concentrations. This paper reports on pre-pandemic field measurements of CO2 concentration levels conducted for an academic year in 10 classrooms from four primary and a secondary school in Victoria, Australia. Measured CO2 concentrations across the 10 classrooms which were operated with a mix of intermittent natural ventilation and air-conditioning for cooling or heating, on average ranged between 657 ppm and 2235 ppm during school hours with median over 1000 ppm in 70% of classrooms. All 10 classrooms in the study exceeded the Australian recommended limit of 850 ppm. Using average peak CO2 concentrations from year-long measurements, estimated ventilation rate (VR) of 4.08 Ls-1 per person show under-performing classrooms where 60% had VRs 35–40% lower than the 10-12 Ls−1 per person Australian recommendation. Estimated VR range of 1.24–2.07 Ls-1 per person using peak maximum CO2 levels were 19–30% lower than ASHRAE recommendation of 6.7 Ls-1 per person. These VRs translate to a range of air change rates on average between 0.52 and 0.88 h−1 ± 0.26–0.59, well below the 6.0 h−1 recommendation for good indoor ventilation by the World Health Organisation in the context of COVID-19 pandemic. Characterisation of ventilation and indoor air quality in current Australian classroom stock is critical for the improvement of classroom design, induction on room operating practices, understanding of the school community on the relevance of building ventilation on school performance and health, and development of appropriate ventilation and indoor air quality guidelines for schools.

Measuring the quantity of harmful volatile organic compounds inhaled through masks

An increase in the concentration of environmental particulate matter and the spread of the COVID-19 virus have dramatically increased our time spent wearing masks. If harmful chemicals are released from these masks, there may be harmful effects on human health. In this study, the concentration of volatile organic compounds (VOCs) emitted from some commonly used masks was assessed qualitatively and quantitatively under diverse conditions (including different mask material types, time between opening the product and wearing, and mask temperature). In KF94 masks, 1-methoxy-2-propanol (221 ± 356 µg m–3), N,N-dimethylacetamide (601 ± 450 µg m–3), n-hexane (268 ± 349 µg m–3), and 2-butanone (160 ± 244 µg m–3) were detected at concentrations 22.9–147 times higher than those found in masks made from other materials, such as cotton and other functional fabrics. In addition, in KF94 masks, the total VOC (TVOC) released amounted to 3730 ± 1331 µg m–3, about 14 times more than that released by the cotton masks (267.5 ± 51.6 µg m–3). In some KF94 masks, TVOC concentration reached over 4000 µg m–3, posing a risk to human health (based on indoor air quality guidelines established by the German Environment Agency). Notably, 30 min after KF94 masks were removed from their packaging, TVOC concentrations decreased by about 80% from their initial levels to 724 ± 5.86 µg m–3; furthermore, 6 h after removal, TVOC concentrations were found to be less than 200 µg m–3. When the temperature of the KF94 masks was raised to 40 oC, TVOC concentrations increased by 119–299%. Since the types and concentrations of VOCs that will be inhaled by mask wearers vary depending on the mask use conditions, it is necessary to comply with safe mask wearing conditions.

IAQ in CCU units: an experimental and numerical investigation based on the outlet air height (case study: Namazi Hospital, Shiraz)

Indoor air quality (IAQ) is a significant concern that affects our health. Recent studies show how poor IAQ amplifies the effects of airborne viruses, which endanger the health of the population relative to the COVID-19. This study aims to find the relationship among IAQ, the location of the air outlet valve and the behavior of the IAQ indicators in the cardiac care unit (CCU) at Namazi Hospital, Shiraz, Iran. In this context, the condition of the air outlet valve can play an important part in preparing a better IAQ. To test the hypothesis, articles based on IAQ guidelines have been studied. Also, certain emissions (CO2, CO, PM2.5 and PM10) have been measured, and the relationship between IAQ, the location of the air outlet valve and the behavior of these emissions in the patient’s room at Namazi Hospital. This room has been analyzed using computational fluid dynamics for the prediction of the specification of incoming air flow particles. Also, a Eulerian–Lagrangian model was used. In constant, the turbulence model (realizable k – ԑ) and discrete particle model were employed. The results show that when the outlet valve is placed on the wall at 20 cm, it decreased particle deposition in the room, and as a result, IAQ will be improved and at the same time, the chances of transmitting infectious diseases will be reduced. It is also indicated that a higher amount of particle deposition fraction (ca. 0.71) obtains when the outlet valve is located on the top of the wall.

Indoor Air Quality Guidelines Connection to IAQ Certification and Labelling Process

Abstract The world’s leading indoor air quality guidelines provide for the identification of certain parameters with a specific limit value based on the latest empirical measurements, however, most of them do not have legal coverage and are voluntary. This leads to unequal assessment of indoor air quality, because there is an identifiable difference between the limit values set out in the various guidelines. And these values would be related to the results obtained during the experimental activities of the application of the specific parameters and the interpretation of their effects on human health. The aim of this IAQ guideline and IAQ certification review was to develop IAQ label for Nordic countries and to find gaps the legislation established by the Latvian government. The development of indoor air quality labels provides an opportunity to maintain and promote the optimal functionality of human physiological processes and the sustainability of the building.

Kindergarten physical setting guidelines: A review from indoor air quality perspectives

The kindergarten’s indoor air contained a number of pollutants, including total volatile organic compounds, particulate matter, carbon monoxide and insufficient ventilation with high carbon dioxide levels, which exceeded the indoor air quality (IAQ) guideline. The presence of these pollutants is caused by various factors including inappropriate physical setting. Indisputably, authorities throughout the countries provide guidelines for designing kindergartens' spaces, however it is limited to general explanations and only guided by early education compliance. It is vital to determine which kindergarten regulations may contribute to poor IAQ. This paper explores national kindergarten physical setting guidelines and how it affects IAQ. A document analysis method was used to determine the characteristics and differences between kindergarten guidelines. Firstly, the composition of each kindergarten guideline was itemised. Then, the study was conducted by making comparisons of the identified items. All the criteria were further reviewed from IAQ perspectives. This study was conducted on guidelines in Australia, Canada, the United States, Singapore and Malaysia. There are five physical setting requirements that influence IAQ : minimum indoor space required per child, sleep area, kitchen and food preparation area, ventilation requirements and furniture and finishes. All activities happen in this microenvironment contribute to IAQ, which is also affected by the ventilation system, furniture and finishes selection. It can be concluded that there is still room for improvement in existing guidelines by taking into account the indoor air perspective. Aside from the main function of kindergarten to provide education, the physical setting of kindergarten also plays a significant role in the growth and health of chidren.

Indoor air quality and the resident's health complaints after eruption of Mount Sinabung, Indonesia

The purpose of this study was to measure the concentration of exposure to indoor particulate matter (PM1, PM2.5, PM10), CO2, RH, and temperature and to evaluate public health complaints due to volcanic ash after the eruption of Mount Sinabung. A correlation analytic was assessed with a cross sectional approach at Payung, Gurukinayan and Perbesi villages from April to July 2021. The level of particles (PM1, PM2.5, PM10), CO2, temperature and humidity were measured by the AS-LUNG type 0019 instrument, Academia Sinica, Taiwan. Respondents' health complaints were evaluated by interviewing respondents using questionnaires. The Mann Whitney U test was used to analyze the differences levels of particles in the area zone. Multivariate analysis of covariance (MANCOVA) was used to evaluate the effect between the concentrations of particulate matter exposure on respondents’ health complaints. The results showed that the mean concentration of exposure to PM1, PM2.5, PM10 in Perbesi and Gurukinayan villages was above maximum level required by Indonesia indoor air quality guideline No. 1077 while CO2 was still below the maximum level required. According bivariate test, there was a significant difference in particle concentration between three villages (p-value = 0.00) and in particle concentration between area zone (p-value = 0.00). The MANCOVA test showed that exposure to PM1, PM2.5, PM10, CO2, RH, and temperature has an effect on eye complaints (p-value &lt;0.05), exposure to PM1, PM2.5, PM10, and RH (p-value &lt;0.05) has an effect on respiratory complaints, and exposure to PM10 (p-value &lt;0.05) has an effect on skin diseases.

Optimizing air purification for household particulate matters using sensor-based and time-based intervention strategies

Filtration efficiency of portable air cleaner (PAC) is affected by resident perceptions and adherences to when and how to operate the PAC. Incorporating PAC with smart control and sensor technology holds the promise to effectively reduce indoor air pollutants. This study aims to evaluate the efficiency of a PAC at removing indoor fine particulate matters (PM2.5) exposure under two automated operation settings: (1) a time-based mode in which the operation time is determined based on perceived time periods of indoor pollution by residents; (2) a sensor-based mode in which an air sensor monitor is used to determine the PAC based on the actual PM2.5 level against the indoor air quality guideline. The study was conducted in a residential room for 55 days with a rolling setting on PAC (no filtration, sensor-based, time-based filtrations) and a continuous measurement of PM2.5. We found that the PAC operated with sensor-based mode removed PM2.5 concentrations by 47% and prolonged clean air (<35 μg/m3) period by 23% compared to the purifications with time-based mode which reduced PM2.5 by 29% and increased clean air period by 13%. The sensor-based filtration identified indoor pollution episodes that are hardly detected by personal perceptions. Our study findings support an automated sensor-based approach to optimize the use of PAC for effectively reducing indoor PM2.5 exposure.

A longitudinal study on the effects of hygro-thermal conditions and indoor air pollutants on building-related symptoms in office buildings.

We conducted a longitudinal epidemiological study for over 1year in Tokyo and Osaka, Japan, beginning June 2015, to examine the association between indoor environmental factors and building-related symptoms (BRSs) in office workers. Data were obtained from 483 subjects (225 females and 258 males) in 24 office rooms in 11 office buildings. Environmental monitoring was conducted for hygro-thermal conditions and carbon dioxide and sampling was performed for indoor air pollutants. Questionnaires were concurrently administered to collect information on participants' perceptions of their comfort and health and the conditions of the work environments. Multivariable analyses revealed that upper respiratory symptoms were significantly correlated with a decrease in both relative [odds ratio (OR): 0.77; 95% confidence intervals (CI): 0.62-0.95; p=0.014] and absolute humidity (OR: 0.89; 95% CI: 0.81-0.97; p=0.008). Statistically, significant evidence was found that average relative humidity of <38% (OR: 2.68; 95% CI: 1.36-5.27; p=0.004) showed the most significant association with increased risk of upper respiratory symptoms. Air concentrations of carbon dioxide showed no significant correlation with BRSs at mean concentrations <1000 ppm in most buildings surveyed. Most indoor air pollutant concentrations were relatively low or lower than the values set by indoor air quality guidelines and the values of thresholds for sensory irritation. Air concentrations of indoor air pollutants showed no significant correlation with BRSs. Our data emphasize the importance of appropriate humidity control during low humidity in winter.