Indoor Air Quality Standards Research Articles

Optimal control strategy for a cutting-edge hybrid ventilation system in classrooms: Comparative analysis based on air pollution levels across cities

Natural ventilation has the potential to enhance indoor air quality in classrooms with elevated CO2 levels, although it may introduce outdoor pollutants. This study introduces a novel controller for automatic windows that simultaneously monitors outdoor air pollution and temperature, synchronizing window openings with mechanical ventilation system to create a comfortable, healthy, and energy-efficient indoor environment. The practicality of the proposed controller is assessed for a classroom in Delhi, Warsaw, and Stockholm, each with contrasting climates and outdoor pollution levels, specifically PM2.5 and NO2. The controller parameters are optimized for each city using a non-dominated sorting genetic algorithm (NSGA-II) to find the best trade-off between thermal comfort, CO2 levels, and energy consumption. The results show that the controller successfully met the indoor air quality standards in all cities; however, its operation was significantly influenced by the climate and pollution levels. While natural ventilation was utilized for 44% and 31% of the year in Warsaw and Stockholm, respectively, it was used for only 11% of the year in Delhi, the most polluted city. The optimization process significantly reduced energy use across all cities while also successfully reducing indoor CO2 concentrations. Although thermal comfort decreased slightly, it remained within acceptable thermal comfort conditions.

Comprehensive analysis of classroom microclimate in context to health-related national and international indoor air quality standards.

Indoor air quality (IAQ) and indoor air pollution are critical issues impacting urban environments, significantly affecting the quality of life. Nowadays, poor IAQ is linked to respiratory and cardiovascular diseases, allergic reactions, and cognitive impairments, particularly in settings like classrooms. Thus, this study investigates the impact of indoor environmental quality on student health in a university classroom over a year, using various sensors to measure 19 environmental parameters, including temperature, relative humidity, CO2, CO, volatile organic compounds (VOCs), particulate matter (PM), and other pollutants. Thus, the aim of the study is to analyze the implications of the indoor microclimate for the health of individuals working in the classroom, as well as its implications for educational outcomes. The data revealed frequent exceedances of international standards for formaldehyde (HCHO), VOC, PM2.5, NO, and NO2. HCHO and VOCs levels, often originating from building materials and classroom activities, were notably high. PM2.5 levels exceeded both annual and daily standards, while NO and NO2 levels, possibly influenced by inadequate ventilation, also surpassed recommended limits. Even though there were numerous exceedances of current international standards, the indoor microclimate quality index (IMQI) score indicated a generally good indoor environment, remaining mostly between 0 and 50 for this indicator. Additionally, analyses indicate a high probability that some indicators will exceed the current standards, and their values are expected to trend upwards in the future. The study highlighted the need for better ventilation and pollutant control in classrooms to ensure a healthy learning environment. Frequent exceedances of pollutant standards can suggest a significant impact on student health and academic performance. Thus, the present study underscored the importance of continuous monitoring and proactive measures to maintain optimal indoor air quality.

Comparative Assessment of Insulation Materials for Improving Indoor Air Quality in Building Retrofit

This paper evaluates the impacts of different insulation materials on Indoor Air Quality (IAQ) and occupant health with a focus on the Volatile Organic Compound (VOC) emissions. The main aim is to identify options that minimize exposure rates while improving IAQ and energy in retrofitted buildings. A comprehensive literature review was conducted synthesizing scholarly articles, guidelines from international organizations, and information on pollutants, IAQ standards, and retrofit strategies. The findings show high emission rates for some insulation materials that could negatively affect health. Hemp insulation in contrast was identified as a promising solution exhibiting low VOC emissions compared to other insulation materials. As sustainable construction practices advance, hemp insulation emerges as a viable retrofit strategy for social housing by synergistically addressing performance gaps related to energy conservation, air quality, and thermal comfort. The synthesis of evidence from this paper suggests that, from environmental and public health perspectives, certain insulation materials are preferable for improving IAQ and reducing the risk of exposure to indoor air pollutants in retrofitted buildings.

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.

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.

Cardiorespiratory effects of indoor ozone exposure during sleep and the influencing factors: A prospective study among adults in China

Ambient ozone (O3) is recognized as a significant air pollutant with implications for cardiorespiratory health, yet the effects of indoor O3 exposure have received less consideration. Furthermore, while sleep occupies one-third of life, research on the health consequences of O3 exposure during this crucial period is scarce. This study aimed to investigate associations of indoor O3 during sleep with cardiorespiratory function and potential predisposing factors. A prospective study among 81 adults was conducted in Beijing, China. Repeated measurements of cardiorespiratory indices reflecting lung function, airway inflammation, cardiac autonomic function, blood pressure, systemic inflammation, platelet and glucose were performed on each subject. Real-time concentrations of indoor O3 during sleep were monitored. Associations of O3 with cardiorespiratory indices were evaluated using linear mixed-effect model. Effect modification by baseline lifestyles (diet, physical activity, sleep-related factors) and psychological status (stress and depression) were investigated through interaction analysis. The average indoor O3 concentration during sleep was 20.3 μg/m3, which was well below current Chinese indoor air quality standard of 160 μg/m3. O3 was associated with most respiratory indicators of decreased airway function except airway inflammation; whereas the cardiovascular effects were only manifested in autonomic dysfunction and not in others. An interquartile range increases in O3 at 6-h average was associated with changes of −3.60 % (95 % CI: −6.19 %, −0.93 %) and −9.60 % (95 % CI: −14.53 %, −4.39 %) in FVC and FEF25–75, respectively. Further, stronger effects were noted among participants with specific dietary patterns, poorer sleep and higher level of depression. This study provides the first general population-based evidence that low-level exposure to indoor O3 during sleep has greater effects on the respiratory system than on the cardiovascular system. Our findings identify the respiratory system as an important target for indoor O3 exposure, and particularly highlight the need for greater awareness of indoor air quality, especially during sleep.

Mitigation strategies to reduce particulate matter concentrations in civil engineering laboratories

In the departments of civil engineering, many experiments are conducted in laboratories for educational and research purposes. Varying degrees of respirable dust are generated as the outcome of these experiments, which could cause harm to instructors’ and students’ health. This study is devised to highlight the importance of indoor air quality in university laboratories. As part of the research, four different particulate matter (PM) sizes (PM1.0, PM2.5, PM4.0, and PM10) were measured during specific experiments—sieve analysis, preparation of the concrete mixture, crushing aggregate by jaw crusher, dynamic triaxial compression test, sieve analysis of silt specimen, cleaning sieve by an air compressor, and proctor compaction test—being conducted periodically in the laboratories of civil engineering departments. The measured values are mainly high compared to indoor air quality standards. Mitigation strategies were applied to reduce indoor air PM levels in the three experiments that contained the highest PM levels. The results have shown that mitigation strategies applied as control measures could make a remarkable difference in protecting instructors and civil engineering students.

Health Risk Assessment of Indoor Formaldehyde Exposure in Facilities for Medically Vulnerable People

A health risk assessment was conducted using indoor formaldehyde concentrations measured during a four-year period from 2019 to 2022 for 322 facilities within Busan Metropolitan City. In the facilities, the average concentration of formaldehyde was 26.7 <i>μg</i>/m3 for general hospitals, 27.4 <i>μg</i>/m3 for nursing hospitals, 17.8 <i>μg</i>/m3for daycare centers, 42.9 <i>μg</i>/m3 for postpartum care centers, and 14.1 <i>μg</i>/m3 for elderly care facilities. As for the health risk of formaldehyde, workers in hospitals, daycare centers, postpartum care centers, and elderly care facilities had ECR (excess cancer risk) values of 3.54 × 10-5, 2.84 × 10-5, 6.84 × 10-5, and 1.86 × 10-5 for CTE (central tendency exposure), respectively. Based on the Busan City ordinance seven out of 322 facilities in this study were found to be non-compliant. When the risk was calculated for individual data according to the exposure of workers in each facility, 303 ECR values (94%) exceeded 1.0 × 10-5. If excess cancer risk is calculated by assuming a gradual change in formaldehyde concentration, the current maintenance standard (70 <i>μg</i>/m3) is insufficient to provide appropriate safety for workers, patients and residents. Therefore, higher stringent values than 50 <i>μg</i>/m3 are required to obtain indoor air quality standards for formaldehyde that meet an ECR of 1.0 × 10-4.

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.

Assessing the impact of ventilation systems on indoor air quality: a mock-up experiment in Dubai

Indoor Air Quality (IAQ) has become an important concern in Dubai, driven by public health awareness, environmental regulations, and government initiatives. The Dubai Municipality has introduced guidelines and standards for IAQ in residential and non-residential buildings, emphasizing ventilation, material selection, and testing protocols. IAQ monitoring and testing are encouraged, and public awareness campaigns educate individuals about IAQ and its impact on health. Green building regulations in Dubai also address IAQ considerations. The Dubai Municipality has comprehensively assessed IAQ in public buildings, leading to stringent regulations. However, research on IAQ improvement and challenges associated with apartment ventilation systems is limited. This study aims to evaluate the IAQ improvement and potential issues of a ventilation system in an apartment through a mock-up experiment. Factors such as air volume, ventilation system type, and supply/exhaust duct configuration are analyzed. The results show that installing a ventilation device with a ventilation rate of 0.3–0.8 times/h reduces Formaldehyde (HCHO) and Volatile Organic Compounds (VOCs) concentrations by 30%–50%. The IAQ improvement is not significantly influenced by air volume. Each room supply/exhaust method shows a 10% higher reduction in VOC concentrations than the supply/kitchen exhaust unit method. Preventing backflow and addressing cold drafts are recommended during ventilation system installation. Noise measurements comply with standards in most cases. These findings contribute to developing guidelines for ventilation system design and installation in apartments, promoting healthier indoor environments. Further research with a broader range of ventilation devices and real-world conditions is recommended to validate these findings.

The disease burden related to time-weighted PM2.5 exposure in China and the potential health benefits of the national standards for indoor air quality: A modeling study

PM2.5 pollution is a major environmental risk factor, causing substantial disease burden and economic loss. The Indoor Air Quality Standard (GB/T 18,883–2022) with the targeted daily average indoor PM2.5 concentration (50 μg/m3) has just been issued in China. To determine whether this new guideline can provide sufficient protection, we evaluate the health and economic burden attributable to the time-weighted average PM2.5 exposure under the three scenarios related to this guideline, using the Global Burden of Disease (GBD) and Willingness-to-pay (WTP) method based on the disease mortality rate, exposure-response relationship and socio economic data. The annual mean time-weighted average PM2.5 (TWPM) concentration in 2020 under the Unchanged, Indoor Air Policy (IAP), Indoor and Outdoor Air Policy (IOAP) scenario were 22.4, 21.7 and 17.5 μg/m3 in China, respectively. Compared with the Unchanged scenario, in which the TWPM-related premature deaths and economic burden were estimated to be 1.22 million and 3.35 trillion RMB Yuan, 0.03 million premature deaths and 8.74 billion RMB Yuan were estimated to be avoided in the IAP scenario; 0.18 million premature deaths and 58.58 billion RMB Yuan in the IOAP scenario. The greater TWPM-related mortality occurred in the heavily polluted and densely populated region, such as the Beijing-Tianjin-Hebei, Fenwei Plain and Sichuan and Chongqing region. The TWPM-related disease burden in China remained obvious even if China complies with the new standard. In comparison to simply improving indoor air quality, boosting both indoor and outdoor air quality may achieve more significant health and economic benefits. Therefore, with the goal to improve indoor air quality, it is still necessary to strengthen outdoor ambient air quality improvement actions.

Study on formulation of standard limits for trichloroethylene and tetrachloroethylene in "Standards for indoor air quality（GB/T 18883-2022）" in China

There are clear indoor air pollution sources of trichloroethylene and tetrachloroethylene. A large number of epidemiological evidence has confirmed their carcinogenic toxicity and non-carcinogenic toxicity. Several countries and international organizations have paid attention to indoor air trichloroethylene and tetrachloroethylene. It has been also assessed that there should be certain potential health risk of indoor air trichloroethylene and tetrachloroethylene in China. Based on the latest research results of health risk assessment of indoor air trichloroethylene and tetrachloroethylene, the "Standards for indoor air quality (GB/T 18883-2022)" added trichloroethylene and tetrachloroethylene as indicators. The index limit of trichloroethylene is 6 μg/m3 for an 8-hour average concentration. The index limit of tetrachloroethylene is 120 μg/m3 for an 8-hour average concentration. The technical contents related to the determination of the standard limits of trichloroethylene and tetrachloroethylene in indoor air were analyzed and discussed, including the sources, the exposure, the health effects, the determination of the limit values, and the recommendations for standard implementation. It also proposed recommendations for the implementation of"Standards for indoor air quality (GB/T 18883-2022)".

Study on formulation and revision of detection methods of "Standards for indoor air quality (GB/T 18883-2022)" in China

The formulation and revision of the detection methods of indoor air quality standards is an important, rigorous and delicate endeavor. This paper introduced the formulation and revision of the detection methods of the standards for indoor air quality (GB/T 18883-2022), focusing on the revision process, revision principles, main adjustments and technical points of some key indicators to facilitate users to better understand and apply the detection methods in standards for indoor air quality (GB/T 18883-2022).

Study on revision of standard limits for nitrogen dioxide in "Standards for indoor air quality（GB/T 18883-2022）" in China

Nitrogen dioxide (NO2) is an important indoor air pollutant, with both outdoor and indoor sources contributing to indoor NO2 exposure levels. Considering the association of high NO2 exposure with adverse health effects, the Standards for indoor air quality (GB/T 18883-2022) have been revised to further restrict indoor NO2 limit values. The 1-h average concentration limit value for NO2 has been reduced from 0.24 mg/m3 to 200 μg/m3.This study analyzed the technical contents related to the determination of the limits of indoor NO2 in Standards for Indoor Air Quality (GB/T 18883-2022), including source, exposure level, health effects, and the process and evidence basis for determining the limit value. It also proposed prospects for the direction for the implementation of the indoor NO2 standard.

Study on formulation and revision of standard limit for formaldehyde in the "Standards for indoor air quality（GB/T 18883-2022）" in China

Formaldehyde, as an important pollutant in indoor air, has always been of great concern. In the newly issued "Standards for indoor air quality (GB/T 18883-2022)", the standard limit of formaldehyde has been restricted to 0.08 mg/m3. In order to better promote the implementation and application of this new standard, this study reviewed and interpreted the relevant technical content for determining the standard limit, including the indoor concentration and human exposure levels of formaldehyde, the health effects of formaldehyde, and the derivation of safety reference values. It also proposed prospect for the future development and revision of quality standards for formaldehyde in indoor air.

Revision and prospect of "Standards for indoor air quality（GB/T 18883-2022）" in China

The formulation and revision of the detection methods of indoor air quality standards is an important, rigorous and delicate endeavor. The standards for indoor air quality (GB/T 18883-2022) were issued by the State Administration of Market Regulation and the Standardization Administration on July 11, 2022, and implemented on February 1, 2023 by replacing indoor air quality standards (GB/T 18883-2002). The revised standard specifies hygienic requirements for physical, chemical, biological and radioactive indicators in indoor air and the corresponding test methods. This article interpreted the revision background, drafting principles, main indicators and methods, as well as the revision basis of the standards. Recommendations for the implementation of the standards are also proposed.

Study on formulation and revision of standard limits for inhalable particulate matter (PM10) and fine particulate matter (PM2.5) in "Standards for indoor air quality（GB/T 18883-2022）" in China

The pollution and health effects of indoor inhalable particulate matter (PM10) and fine particulate matter (PM2.5) are increasingly receiving public attention. The"Standards for indoor air quality (GB/T 18883-2022)"has revised the standard limit for PM10 and added the standard limit for PM2.5. This study analyzed and interpreted the relevant technical contents of the revision of the standard limits for two indicators, including the exposure status, health effects, and the basis for the determination of the limit value. It also proposed prospects for the future development and revision of standard limits for indoor particulate matters.

Study on formulation and revision of standard limits for radon in "Standards for indoor air quality (GB/T 18883-2022)" in China

Public exposure to radon has attracted increasing public concern. The newly issued "Standards for indoor air quality (GB/T 18883-2022)" has revised the radiological parameters of radon. This study analyzed and discussed the relevant technical contents about the derivation of radon limit, including the distribution level for indoor radon, exposure pathway, health effects, and the process for establishing the standard limits. Specific implementation and evaluation suggestions are also proposed.

Study on formulation and revision of standard limits for total bacteria count in "Standards for indoor air quality（GB/T 18883-2022）" in China

The total bacteria count has been attracting attention as an important pollutant in indoor air, and its standard limit was tightened to 1500 CFU/m3 in "Standards for indoor air quality (GB/T 18883-2022)".The technical contents related to the determination of the indoor air standard limits for total bacteria count were analyzed and studied, including the environmental existence level, exposure status, the health effects and the derivation of the limit value. It also proposed prospects for the future development and revision of quality standards for total bacteria count in indoor air.