Introduction
The 2021 WHO Air Quality Guidelines[1] included four good practice statements to help guide actions to decrease concentrations of ultrafine particles (UFP) and ultimately reduce population exposure to UFP. The good practice statements included recommendations to expand common air quality monitoring to include size-segregated and real-time measurements of UFP along with...
Background
Exhaled SARS-CoV-2-containing aerosols contributed significantly to the rapid and vast spread of covid-19. However, quantitative experimental data on the infectivity of such aerosols is missing. Knowing the emission rates of infectious viruses from normal respiratory activities enables more accurate modelling of disease transmission in indoor environments.
Method
We collected the...
Objective: As an indoor environment, public transport is subject to special conditions with many passengers in a comparatively small space. Therefore, both an efficient control of the climatic parameters and a good air exchange are necessary to avoid transmission and spread of respiratory diseases. However, in such a dynamic system it is practically impossible to determine pathogenic...
Objective: Urbanization and rising energy demand in buildings challenge public health by increasing airborne disease transmission risks in crowded indoor spaces. While improved ventilation has been recommended during the COVID-19 pandemic to lower infection risks, it also raises energy consumption, creating a trade-off between energy use and health protection. Current strategies like...
Objective
Poor indoor air quality (IAQ) can impact health, a concern emphasized during the COVID-19 pandemic. Belgium’s Federal Public Services (FPS) of Health launched the Indoor Air Quality Platform to address this. This platform unites public agencies, academics, and industry representatives to enhance IAQ in public enclosed spaces (e.g., restaurants, hotels, cultural and sports venues)...
Introduction
Children in Europe spend a substantial amount of their time in classrooms, where indoor air quality (IAQ) guidelines are often not met. Poor IAQ — shaped by factors such as bioaerosols (including bacteria, viruses), particulate matter (PM), and volatile organic compounds — has been associated with respiratory morbidity and infectious disease transmission. While ventilation...
Background/Objective
The growing concern about the rapid spread of respiratory diseases has reinforced the importance of environmental monitoring of infectious diseases as an indispensable tool for public health. In particular, monitoring respiratory viruses in air samples is essential for early detection, prevention, and control of epidemic outbreaks, providing a more comprehensive...
Objective: Contemporary outdoor PM2.5 levels are generally low in Western cities, which may make indoor contributions to personal exposure more significant. We aim to compare acute effects of PM2.5 measured as outdoor concentration versus personal exposure on respiratory pathophysiologic indicators in adults with or without asthma.
Methods: From 2021-2023, we conducted a panel study in 42...
High CO₂ levels in indoor spaces not only have direct adverse affects on human wellbeing but are also, in most cases, a reliable indicator of the amount of rebreathed air and thus for the risk of spread of airborne diseases. Despite its importance, large-scale datasets on indoor CO₂ levels across diverse, publicly accessible spaces remain scarce.
Existing research on indoor CO₂ levels so...
Introduction:
The concentration of carbon dioxide (CO2) is commonly used as a proxy for indoor air quality, particularly for assessing ventilation in indoor environments and estimating the risk of airborne transmission. Ventilation rates are commonly estimated using the mass balance equation under the assumption of a well-mixed environment. To estimate transmission risk, the Wells-Riley...
The COVID-19 pandemic underscored the vital role of indoor air quality (IAQ) in reducing airborne disease transmission indoors. Far-Ultraviolet (FAR-UV) technology, emitting light between 200-235 nm, emerges as a promising alternative to traditional wavelengths of Germicidal Ultraviolet (GUV), promoting airborne disinfection without many of the safety concerns related to improperly installed...
As airborne transmission of expiratory droplets is one of the important pathways for viral respiratory diseases including the recent pandemic COVID-19 to infect healthy people, it is extremely important to explore and understand the detailed mechanisms of virus spread through airborne expiratory droplets. To reduce the risk of exposure to viral respiratory diseases, the World Health...
Background: While the areas of study of indoor air and infectious disease epidemiology both emphasize the use of modeling for understanding disease transmission systems, siloing of disciplines, different model assumptions, and different vocabulary have limited the emergence of transdisciplinary science around airborne infectious diseases. Here we show that integration of simple air and...
The COVID-19 pandemic significantly contributed to deepen our understanding of respiratory virus transmission, emphasizing the critical role of indoor environments and the necessity of effective ventilation. Historically, public health guidelines primarily addressed large droplet as transmission routes. It was not until the spring of 2021, due to the increasing scientific evidence, that major...
Introduction:
Application of mobile air cleaning devices (MACs) in schools has been put forward as a potential control measure to limit and/or prevent respiratory virus outbreaks through reduction of viral concentrations in air. However, evidence on the effectiveness of air cleaning technologies on viral levels in general, and in schools specifically is lacking. Exploring airborne viral...
Exposure to bacteria and fungi in enclosed spaces for long periods of time has been associated with adverse health effects. Airborne fungi can cause lung disease and irritation of the mucous membrane and airborne bacteria are possible catalysts for conditions such as asthma, rhinitis and bronchitis. The issue of healthy educational buildings is a global concern because children are...
Luca Fontana
Improving indoor air quality (IAQ) can result in a range of measurable health benefits, including reduction of infectious disease risks, and cognitive performance improvements. Using engineering controls to minimize the indoor transmission of airborne pathogens saves lives and improves health cost-effectively. Despite a strong evidence base, gaps remain in understanding disease transmission....
Objective: Protecting indoor air from infectious aerosols is both a significant challenge and a remarkable opportunity for improving public health. Recent standards, such as ASHRAE 241, set equivalent clean air delivery rate targets to reduce airborne transmission risk. While increased ventilation and added filtration can meet these targets in some settings, many environments—such as...
Introduction:
In office spaces, users spend around 1/3 of their daily time, thus maintaining good air quality is an important aspect of keeping a healthy and efficient working environment. As office occupants usually have a regular daily and weekly schedule, machine learning can be a useful method to find the air quality pattern. Its result can benefit the indoor activities to improve the...
Nowadays, the use of technically upgraded, cost-efficient, real-time, monitoring sensors has led to increased efficiency in indoor air quality (IAQ) data collection. Combined with the means of citizen science (i.e. collection of occupants activity data), the large amount of air quality data comprises a challenging opportunity to investigate further the factors influencing the quality of the...
Objective
The idea of creating a computational tool that, with a high degree of interactivity, allows demonstrating both the temporal evolution of the concentrations of a biological contaminant and carbon dioxide (CO2) within an indoor compartment arose during the preparation phase of the modules that the first author taught on a course organised by REHVA about the Safe Operation of Buildings...
Introduction/Objective:
Air pollution significantly harms human health, contributing to respiratory and cardiovascular diseases as well as overall declines in well-being. There is a growing need for more effective and comprehensive methods to assess the toxicity of air pollutants. Typically, the evaluation of particle toxicity has relied on in vitro methods, using cell cultures exposed to...
Introduction: Respiratory infections are a leading cause of morbidity in pediatric populations, with airborne transmission playing a significant role. The COVID-19 pandemic has underscored the impact of indoor air quality on human health, particularly in school environments, where children spend a substantial amount of time. Addressing this issue, an interdisciplinary group—the "Indoor Air...
Exposure characterization (1) during the production phases (freeze-drying of graphene ink obtained by liquid phase exfoliation of graphite layered crystals (2)) of few layers graphene (FLG) was carried out in a Research and Development (R&D) laboratory, following a multiparametric tired approach based on the Organization for Economic Cooperation and Development (OECD) harmonized guidelines...
Large passenger ships are characterised as enclosed/crowded spaces with frequent interactions, providing conditions that facilitate disease transmission. Moreover, super-spreading events (Abe et al., 2022; Althouse et al., 2020) have been reported to have occurred in these environments. The COVID-19 pandemic demonstrated a profound inability of existing passenger ship policies to...
Background
In order to improve infection control guidelines for healthcare workers, we investigated SARS-CoV-2 in aerosols and risk factors for airborne transmission in healthcare settings during the covid-19 pandemic.
Methods
Briefly, a liquid cyclone was used for air sample collection close to patients at several wards, and an 8-stage NGI impactor (ranging from 0.1 to >8.1µm)...
Objective: To investigate the performance of bioaerosol inactivation/capture in non-thermal plasma (NTP), UV-C photolysis, bipolar ionization (BI), and electrostatic precipitation (ESP) stages of multistage air cleaner, across varying airflow rates of individual and combined stages.
Methods: The prototype air cleaning device operated sequentially through NTP, UV-C, BI, and ESP stages....
The exhaled aerosol plays a crucial role in the transmission of respiratory viruses. It has been found that the inactivation of viruses (influenza A virus and SARS-CoV-2) depends crucially on the pH value and on the salt concentration in the exhaled aerosol particles (Luo et al. 2023, Haddrell et al. 2024, Schaub et al. 2024). During exhalation, particles shrink by losing water and CO$_2$,...
Transport microenvironments are critical indoor settings where exposure to environmental pollutants and respiratory particles poses significant health risks. Commuters in cars, buses and other means of transportation are particularly vulnerable due to the high concentration of pollutants on roads and highways, combined with inefficient filtration systems in vehicle. These factors result in...
The CAVE (Controlled Active Ventilation Environment) laboratory is a purpose-built, climate- and ventilation-controlled indoor laboratory. With a plan area of 206 m² and a height of 10 m, CAVE has been designed to support full-scale "living labs," ranging from small buildings to vehicles and double-decker buses. With a fully furnished, two-story building inside, our laboratory HVAC systems can...
Cleaners are frequently exposed to a wide range of airborne agents, including respiratory sensitizers and irritants. Notably, exposure to bleach and other chlorine-based disinfectants have been associated with an increased risk of respiratory conditions. However, much of the available evidence relies on self-reported exposure data, which may introduce bias toward cleaning agents with more...
Objective: New in-vitro models are currently being developed to predict in vivo adverse outcomes, including using advanced microscopy and spectroscopy techniques to track key events in vitro. The in vitro data will be used to develop in-silico models for quantitative prediction of adverse outcomes in vivo. In order to calibrate and validate the in-silico models, different types of industrial...
Objectives
Transmissibility has increased during the evolution of SARS-CoV-2, possibly by improved airborne transmission. An increased transmission was noted also in many hospitals. We analyzed SARS-CoV-2 in room air of hospitalized Omicron infected patients and compared results with previous findings with pre-Delta variants to study if SARS-CoV-2 was more prevalent in patient rooms after the...
Objective: Higher ventilation rates of work spaces are generally associated with reduced presence of airborne pathogens and improved health outcomes. The spread of respiratory pathogens such as SARS-CoV-2 and tuberculosis, as well as building-related illness are associated with poor air quality in specific work spaces. The clothing and textile industry is a large employer and important...
Real-time infection risk monitoring is essential for public health, enabling early detection interventions to mitigate airborne disease spread in indoor spaces. Current infection risk models, such as the Wells-Riley model, rely on a well-mixed assumption and a constant aerosol exhalation rate, leading to inaccuracies in predicting spatial variations in airborne transmission. Similarly,...
Objective: Little is known on the impact of national COVID-19 preventive measures and ventilation regimes on potential SARS-CoV-2 or other infectious exposure in school environments. Since quantitative SARS-CoV-2 exposure information is not available, 16S rRNA total bacterial load (16S) was considered as a generic microbial indoor air quality marker. We explored whether 16S levels in airborne...
Objective: Human rhinovirus is the most common cause of the common cold worldwide (1). It has been shown that a substantial part of the airborne viruses is found in aerosol particles in the range of 1-4 µm (2). Studying the infectivity of aerosol particles in this range is, however, challenging; therefore, not many studies have been conducted on their infectivity. The aim of this work is to...
Exposure to airborne particles in indoor environments is a significant concern for human health, as the presence of indoor particle sources leads to considerably higher concentrations of particles. The principal sources of particles in indoor environments include cooking activities, burning incense, candles, and mosquito coils, as well as resuspension from movement or cleaning activities and...
COVID-19 pandemic has reignited the discussion on required ventilation rates for indoor spaces. More specifically, the discussion has revolved around the required ventilation rate to efficiently mitigate airborne transmissions in different types of indoor environments with various type of activities. The topic has been studied extensively, and the research has resulted in guidelines and...
Workplaces with exceptional indoor environmental quality (IEQ) significantly influence employees' health, well-being, and safety, ultimately enhancing productivity. The investment in maintaining high IEQ is quickly recouped, with ongoing financial benefits. By fostering an environment that prioritizes employee satisfaction, businesses can achieve greater efficiency and a stronger return on...
AbdulKareem N. AlKahtani1, Mingyu Wang2, Cameron Zielke1, Mohammad Heidarinejad2, Brent Stephens2, Natsumi Nemoto3, Anna Pinsoneault4, Charles H. Williams3, Yuan Shao1, Margaret Sietsema1, Mehdi Amouei Torkmahalleh1.
1Department of Environmental and Occupational Health Sciences, School of Public Health, University of Illinois Chicago (UIC), Chicago, Illinois, United States.
2Department...
Introduction:
The Wells-Riley (W-R) models are commonly used to estimate the risk of airborne transmission in indoor environments, balancing model fidelity and computational efficiency. These models rely, to varying degrees, on the well-mixed hypothesis. Based on this assumption, a mass balance equation for pathogen or quanta concentration can be formulated and solved, incorporating...
Introduction:
Indoor air quality has public health implications because people spend approximately 90% of their time in these environments. This project aims to gather an interdisciplinary team focused on indoor air quality, involving health, microbiology, architecture, and environmental, mechanical, and electrical engineering researchers. In this case, the indoor environments being...
M. LILJENBERG, J TRUYOLS VIVES, C. J. FRAENKEL, P. MEDSTRAND, M. ALSVED, J. LÖNDAHL.
Introduction
Respiratory infection of viruses affects many persons every year, having a large economic and societal impact. Droplets and droplet nuclei from speaking, coughing, and sneezing has been investigated at least since in 1946 (Duguid, 1946), up until present day where the Covid-19 pandemic...
Indoor ultrafine particles (UFPs) represent a growing concern, as people spend approximately 90% of their time indoors (Klepeis et al., 2001). UFPs, which are particularly prevalent in indoor environments, are produced by a variety of sources, including combustion processes like cooking (Lachowicz et al., 2022, Massey et al., 2012). Given the importance of cooking as a daily activity, it is...
In the wood processing industry, exposure to dust is one of the major potential health threats for workers. During sawing, high concentrations of particles of different sizes are generated. They are potentially harmful for human health and exposed workers can report occupational diseases such as allergic rhinitis, chronic bronchitis, lung fibrosis, asthma, nasal and sinonasal cancers. The...
Background: Occupational exposure to soluble chlorinated platinum (Pt) salts, commonly called chloroplatinates, is a known cause of Pt salt sensitization (PSS) and occupational asthma. When PSS has been established, sensitized workers are usually redeployed to jobs with low chloroplatinate exposure levels or environments without exposure to prevent development of occupational allergy and...
Background/Objective
People generally spend more time indoors than outdoors, yet there is still a lack of regulations addressing particulate matter concentrations in indoor environments. Indoor air quality plays a crucial role in human health, especially in enclosed spaces where individuals, particularly children, are exposed to airborne pollutants for extended periods and are especially...
Indoor environmental quality (IEQ) can directly impact the comfort, productivity, and health of occupants. Given that individuals spend approximately 90% of their time indoors, the quality of the indoor environment directly impacts human well-being. For university students, dormitories are not just places of rest but serve as essential restorative environments that support their academic...
Objectives: This paper introduces the "Human-Centric Indoor Climate for Healthcare Facilities" (HumanIC) project, granted in the EU Marie Curie Program framework. It aims to advance the understanding of the human-centric indoor climate (HCC) within hospital environments, focusing on its impact on patient safety, infection control, thermal comfort, and energy efficiency. The objective aligns...
Astatine-211 ($^{211}$At), with a half-life of 7.216 hours, which is produced via the $^{209}$Bi(α,2n)$^{211}$At reaction using accelerator is one of the promising radionuclides for targeted alpha therapy. At the accelerator facilities, measurements of airborne radioactivity are required using an ionizing chamber or radioactive aerosol monitor to manage the risk of radiation exposure to...
Particulate matter (PM) has been recognized as leading health risk factors worldwide, contributing to adverse effects for exposed people in life and work environments. During the Covid-19 pandemic period, it has been shown how environmental factors, including ultrafine particles (UFPs) and PM concentrations, may play an important role in SARS-CoV-2 differential distribution and transmission....
Background/Objective
Gas cooking emits NO2, a gas contributing to poor indoor air pollution, and leading to indoor concentrations often exceeding outdoor levels and air quality guidelines. Electric hobs, on the contrary, do not involve combustion and thus do not contribute to increasing indoor NO2 levels. Gas cooking was prevalent in 33% of European households in 2022, although usage...
Objective: For the ecotoxicological assessment of a chemical substance in indoor spaces, it is important to know its partitioning behavior between gas phase, particle phase and settled house dust. Due to the complex interaction of molecules with the different compartments, the dynamics is usually modeled. However, this requires precise knowledge of the physical and chemical properties of the...
Background/Objective
The transmission of SARS-CoV-2 through aerosols has been recognized as a critical pathway for infection, especially in indoor settings with limited ventilation, where people share spaces over extended periods. Despite its importance, during the COVID-19 pandemic period there was a notable scarcity of studies assessing the presence of SARS-CoV-2 genetic material in...
Objectives. Indoor transmission of pathogens between hosts primarily occurs through exhaled respiratory droplets. Transmission mechanisms include direct or indirect contact with contaminated surfaces, and direct or indirect inhalation of droplet nuclei. Droplet trajectory depends primarily on their size among other factors such as ambient thermohygrometric conditions and transport...
Introduction:
In recent years, the scientific community has shown growing concern regarding the effects of indoor air quality on health. The COVID-19 pandemic has also highlighted the importance and necessity of addressing these issues through interdisciplinary approaches. In this context, we formed a team of engineers, architects, microbiologists, and physicians to study air quality in...
Infrared thermography (IR) combined with deep learning offers a promising approach for accurately detecting and localizing leaks in N95 masks, a critical concern in respiratory protection research. This study aims to develop and validate a real-time system that not only identifies leak occurrences but also pinpoints their exact location on the mask perimeter. By leveraging a novel workflow...
Introduction
Bioaerosols represent a relevant component of both indoor and outdoor environments with the potential to cause serious adverse effects on human health [1,2]. Therefore, bioaerosols monitoring becomes a key element in risk evaluation and assessment. To date, new real-time instruments based on the induced fluorescence have been developed, allowing continuous monitoring as...
In the workplace, air quality measurements have revealed a growing presence of ultrafine particles in ambient air. These are mainly due to the growing use of nanoparticles in industry and to dust emissions during manufacturing processes. These ultrafine particles have a very high specific surface area, and numerous studies have shown that some have, for the same mass, increased biological...
Reactive oxygen species (ROS) are considered to be an indicator of particle-induced toxicity. ROS can be either present on the surface of particles or generated through chemical reactions between particles and cells after inhalation. Therefore, measuring particle-bound ROS may be used to assess the harmful effects of inhaling particles. The purpose of this study was to determine ROS in...
Objective: Respirable Crystalline Silica (RCS), classified as a Group 1 carcinogen by the International Agency for Research on Cancer, poses significant health risks when inhaled, including silicosis and lung cancer. Exposure to RCS can occur especially in occupational settings, including in the glass, ceramic, brick and tile industries, where materials are mechanically processed through...
Objectives: Many infection control governmental bodies and international societies have issued recommendations for minimum ventilation in patient rooms in hospitals in the context of covid-19 and before. The recommendations can be summarized to 4-6 air changes per hour (ACH) or 40-60 liters per second and patient. These recommendations may in part be risk-based and in part be issued to reach a...
Objectives
(i) Objective #1: Development and application of IoT-based sensors for a monitoring network of multiple air pollutants at representative semi-enclosed public transport interchanges (PTIs);
(ii) Objective#2: Elucidation of spatial variability of multiple air pollutant concentrations in PTIs using a geographic information system (GIS) to determine of pollution hotspots at PTIs...
The COVID-19 pandemic has led to the proliferation of air purifiers employing various methods to remove volatile organic compounds (VOCs). However, the French Research and Safety Institute for the Prevention of Occupational Accidents and Diseases (INRS) has observed that some purifiers emit high concentrations of ozone (O3), ranging from 100 to over 1,000 ppbv. O3 triggers the oxidation of...
Background: Cleaning activities commonly conducted in educational buildings are intended to promote hygiene and comfortable learning environments. However, using cleaning products can result in exposure to both primary and secondary indoor air pollutants. This exposure arises from the emission of various substances and their interactions with other compounds present in indoor environments, for...
Background and Objective:
The transmission of respiratory pathogens via exhaled droplets and aerosols is a key mechanism in the spread of infectious diseases such as influenza and COVID-19. The physicochemical properties of exhaled respiratory droplets, which vary under different environmental conditions, directly influence the survival and transport of airborne pathogens. Factors such as...
Indoor aerosols typically receive far less attention than outdoor aerosols, which are being permanently monitored in measurement networks. Air quality guidelines are also made for outdoor air quality, even though most people spend most of their time indoors, and although indoor air quality can be much worse than outdoor air quality in some circumstances. Therefore, even though a large part of...
Using thermodynamic and kinetic data for respiratory fluids as input to the biophysical respiratory aerosol model ResAM (Luo et al., 2023; 2025), we show that exhaled particles rapidly desorb H$_2$O and CO$_2$, becoming alkaline, and then absorb gaseous nitric acid (HNO$_3$) and other acidic substances from the ambient air, becoming acidic. The rate of these processes depends primarily on...
