A primary challenge in combatting the ongoing coronavirus disease 2019 (COVID‐19) pandemic is to clarify the definitions and roles of airborne transmission, contact transmission, and droplet transmission of the causative agent, severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2).1 Confusion about these key aspects exists among both the general population, who are interested in evaluating their

In the last two decades, multidisciplinary research teams worked on developing a comprehensive understanding of the transmission mechanisms of airborne diseases. This article reviews the experimental studies on the characterization of the exhaled airflow and the droplets, comparing the measured parameters, the advantages, and the limitations of each technique. To characterize the airflow field, the

Predicted mean vote (PMV) is a prevailing thermal comfort model adopted by thermal comfort standards. To extend its ability in explaining thermal adaptations, the PMV is multiplied by an extension factor. However, the original extended PMV (ePMV) cannot account for thermal adaptations around thermal neutrality, resulting in deviation around thermal neutrality, therefore, is unable to predict thermal

This study is the pioneer assessment of the PCBs in indoor dust particles (from air conditioners) of an urbanized megacity from South Asian. The ∑35 PCB concentration ranged from 0.27 to 152.9 ng/g (mean: 24.84 ± 22.10 ng/g). The tri‐ and tetra‐PCBs were dominant homologues, contributing 57.36% of the total PCB concentrations. The mean levels of Σ8‐dioxin‐like (DL), Σ6‐indicator PCBs and WHO2005‐TEQ

Due to the severe outdoor PM2.5 pollution in China, many people have installed air‐cleaning systems in homes. To make the systems run automatically and intelligently, we developed a recurrent neural network (RNN) that uses historical data to predict the future indoor PM2.5 concentration. The RNN architecture includes an autoencoder and a recurrent part. We used data measured in an apartment over the

To investigate the need of allergic population for indoor environment quality, exposure effects of poor air quality on subjects with respiratory allergies were compared with those on healthy people, including perceptual responses, health symptoms, mental performance, and physiological responses. The experimental intervention was with and without ventilation at thermally neutral rooms, creating two

Air‐change rate is an important parameter influencing residential air quality. This article critically assesses the state of knowledge regarding residential air‐change rates, emphasizing periods of normal occupancy. Cumulatively, about 40 prior studies have measured air‐change rates in approximately 10,000 homes using tracer gases, including metabolic CO2. The central tendency of the air‐change rates

More representative data on source‐specific particle number emission rates and associated exposure in European households are needed. In this study, indoor and outdoor particle number size distributions (10–800 nm) were measured in 40 German households under real‐use conditions in over 500 days. Particle number emission rates were derived for around 800 reported indoor source events. The highest emission

We measured wavelength‐resolved ultraviolet (UV) irradiance in multiple indoor environments and quantified the effects of variables such as light source, solar angles, cloud cover, window type, and electric light color temperature on indoor photon fluxes. The majority of the 77 windows and window samples investigated completely attenuated sunlight at wavelengths shorter than 320 nm; despite variations

The rapid development of automated measurement equipment enables researchers to collect greater quantities of time‐resolved data from indoor and outdoor environments. While significant, the interpretation of the resulting data can be a time‐consuming effort. This paper introduces an automated process of interpreting PM2.5 time‐resolved data and differentiating PM2.5 emissions resulting from indoor

We applied filter forensics, the analysis of dust from the heating, ventilation, and air‐conditioning (HVAC) filters, to measure particle size distribution in 21 residences in Toronto, Canada over a year. Four filters with different nominal efficiencies (Minimum Efficiency Reporting Value (MERV) 8–14 from ASHRAE Standard 52.2) were deployed in each residence each for three months, while the effective

In retail stores, workers are constantly exposed to new manufactured goods. The issue of the exposure of retail workers to volatile organic compounds (VOCs) should clearly be considered. Therefore, this study provides data regarding VOC concentrations in ten French retail stores. The stores were chosen to represent various products: sports goods, shoes and leather, furniture, car equipment, bazaars

This study presents real‐time concentrations of traffic‐related air pollutants during 499 trips conducted by 50 Parisian taxi drivers from PUF‐TAXI project. Ultrafine particles (UFPs), black carbon (BC), and nitrogen dioxide (NO2)/carbon monoxide (CO) were measured inside vehicles by Diffusion Size Classifier Miniature®, microAeth®, and Gas‐Pro®, respectively, for nine hours. Vehicle/trip data characteristics

This work presents an original method to identify priority indoor air pollutants in office buildings. It uses both a chronic risk assessment approach by calculating a hazard quotient, and a hazard classification method based on carcinogenic, mutagenic, reprotoxic, and endocrine disruptive effects. A graphical representation of the results provides a comprehensive and concise visualization of all of

Humans spend approximately 90% of their time indoors, impacting their own air quality through occupancy and activities. Human VOC emissions indoors from exercise are still relatively uncertain, and questions remain about emissions from chlorine‐based cleaners. To investigate these and other issues, the ATHLETic center study of Indoor Chemistry (ATHLETIC) campaign was conducted in the weight room of

Thermal comfort standards are essential to ensure comfortable and enjoyable indoor conditions, and they also help in optimizing energy use. Thermal comfort studies, either climate chamber‐based or field investigation, are conducted across the globe in order to ascertain the comfort limits as per the climatic and other adaptive features. However, very few studies are conducted when the occupants are

This study assessed associations between house characteristics and mold and musty odor, using data from three consecutive (2005, 2010, and 2015) New Zealand House Condition Surveys, involving a total of 1616 timber‐framed houses. Mold, musty odor, and house characteristics were assessed by independent building inspectors. We used multivariate logistic regression analyses mutually adjusted for other

Sleep thermal environments substantially impact sleep quality. To study the sleep thermal environment and thermal comfort in China, this study carried out on‐site monitoring of thermal environmental parameters in peoples’ homes, including 166 households in five climate zones, for one year. A questionnaire survey on sleep thermal comfort and adaptive behavior was also conducted. The results showed that

Chemical filters are the most important devices for removing gas‐phase pollutants in clean rooms. However, the testing concentration of chemical filters is too high for reflecting their performance in a real clean room environment. This study tested the adsorption performance of chemical filters in the two most commonly used shapes at different concentrations. Then, the Langmuir equation and Wheeler‐Jonas

In winter and summer of 2016 and 2017, airborne fungi and house dust were collected in indoors of the village Gunja, which had been flooded, and the control village Gornji Stupnik (Croatia) in order to explore variations of fungal indoor levels, particularly Aspergilli section Nidulantes series Versicolores, as well as fungal metabolites in dust. Levels of airborne Aspergilli (Versicolores) were three

This preliminary investigation highlights the occurrence of organochlorine pesticides (OCPs) in the indoor environment of a megacity, Lahore, Pakistan using the dust ensnared by air‐conditioner filters. The Σ16OCPs concentration ranged from 7.53 to 1272.87 ng/g with the highest percent contribution by ΣDDT (dichlorodiphenyltrichloroethane; 87.21%) and aldrin (6.58%). The spatial variation of OCPs profile

In this study, 30 subjects were exposed to different combinations of air temperature (Ta: 24, 27, and 30°C) and CO2 level (8000, 10 000, and 12 000 ppm) in a high‐humidity (RH: 85%) underground climate chamber. Subjective assessments, physiological responses, and cognitive performance were investigated. The results showed that as compared with exposure to Ta = 24°C, exposure to 30°C at all CO2 levels

The performance of a low‐cost fan filter unit (FFU) in mitigating hazardous particulate matter (PM) levels in a naturally ventilated school classroom is presented. The FFU can be considered as a simplified mechanical ventilation and air‐conditioning system without heating and cooling functions. The FFU improves indoor air quality through introduction of cleaned outdoor air to flush out internally generated

Household humidification is widely practiced to combat dry indoor air. While the benefits of household humidification are widely perceived, its implications to the indoor air have not been critically appraised. In particular, ultrasonic humidifiers are known to generate fine particulate matter (PM). In this study, we first conducted laboratory experiments to investigate the size, quantity, and chemical

It is essential to understand where and how severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is transmitted. Case reports were extracted from the local Municipal Health Commissions of 320 prefectural municipalities in China (not including Hubei Province). We identified all outbreaks involving three or more cases and reviewed the major characteristics of the enclosed spaces in which the

This paper presents pollutant concentrations and performance data for code‐required mechanical ventilation equipment in 23 low‐income apartments at 4 properties constructed or renovated 2013‐2017. All apartments had natural gas cooking burners. Occupants pledged to not use windows for ventilation during the study but several did. Measured airflows of range hoods and bathroom exhaust fans were lower

A new disinfection system utilizing UVC‐LED irradiation was developed. The system was affixed to the toilet seat, and it was challenged by three bacteria strains. Different configurations were tested: 3‐LEDs, 5‐LEDs (two variants), and 8‐LEDs. To determine the arrangement designs of LEDs with the optimum efficacy, two variants of 5‐LEDs configurations were additionally considered—uniform and concentrated

People spend approximately 80% of their time indoor, making the understanding of the indoor chemistry an important task for safety. The high surface‐area‐to‐volume ratio characteristic of indoor environments leads the semi‐volatile organic compounds (sVOCs) to deposit on the surfaces. Using a long path absorption photometer (LOPAP), this work investigates the formation of nitrous acid (HONO) through

There is a worldwide discussion on the role of aerosols in the transmission of SARS‐CoV‐2. The WHO has recently highlighted1 the possible role of aerosols in the transmission of SARS‐CoV‐2. Aerosols containing small respirable particles are increasingly recognized as a potentially important mode of transmission of SARS‐CoV‐2.2-5 We investigate aerosol droplet persistence inside the confined space of

Microbes in buildings have attracted extensive attention from both the research community and the general public due to their close relationship with human health. However, there still lacks comprehensive information on the indoor exposure level of microbes in China. This study systematically reviews exposure levels, the community structures, and the impact factors of airborne bacteria and fungi in

Indoor air pollution (IAP) is a recognized risk factor for various diseases. This paper examines the role of indoor solid fuel exposure in the risk of mycobacterium tuberculosis (TB) in Delhi Metropolitan, India. Using a cross‐sectional design, subjects were screened for a history of active TB and lifelong exposure to IAP sources, such as solid fuel burning and kerosene. The TB prevalence rate in the

Secondary exposure to e‐cigarette aerosol (passive vaping) will soon become a pressing public health issue in the world. Yet, the current knowledge about respiratory depositions of e‐cigarette aerosol through passive vaping in human airways is limited due to critical weaknesses of traditional experimental methods. To fill in this important knowledge gap, this study proposed a special approach involving

The performance of an air cleaner is evaluated by the clean air delivery rate (CADR), which is defined as the measure of the delivery of contaminant‐free air. Herein, we conducted comparative analyses of various particulate air filters with various collection efficiencies. We installed each filter in identical commercial air cleaners to determine the effects of the collection efficiency on the CADR

In this study, we examined the cognitive performance of subtropically acclimatized subjects at an extreme high indoor temperature and the effect of decreased humidity on the cognitive performance at the high temperature. Forty‐eight healthy subjects experienced the three exposure conditions: 26°C/relative humidity (RH) 70%, 39°C/RH50%, and 39°C/RH70% in a climate chamber. During 140‐minute‐long exposures

The determinants of the temporal variability of indoor dust concentrations of semivolatile organic compounds (SVOCs) remain mostly unexplored. We examined temporal variability of dust concentrations and factors affecting dust concentrations for a wide range of SVOCs. We collected dust samples three times from 29 California homes during a period of 22 months and quantified concentrations of 47 SVOCs

Household incense burning is a common ritual behavior in the Asia‐Pacific region but has been associated with inferior developmental outcomes in term infants. We aimed to examine these associations among preterm infants.

We aimed to evaluate the association of the exposure to environmental tobacco smoke (ETS) during pregnancy and infancy with the risk of upper respiratory tract infections (URTI) in infants based on a Chinese birth cohort study. Among 4178 infants who constituted the final study population, 46.8% experienced URTI in their first year of life. The hazard ratios (HR) and 95% confidence intervals (CI) for

This study reports the outcomes of a systematic literature review, which aims to determine the influence of four indoor environmental parameters — indoor air, thermal, acoustic, and lighting conditions —on the quality of teaching and learning and on students' academic achievement in schools for higher education, defined as education at a college or university. By applying the Cochrane Collaboration

During the 2020 COVID‐19 pandemic, an outbreak occurred following attendance of a symptomatic index case at a weekly rehearsal on 10 March of the Skagit Valley Chorale (SVC). After that rehearsal, 53 members of the SVC among 61 in attendance were confirmed or strongly suspected to have contracted COVID‐19 and two died. Transmission by the aerosol route is likely; it appears unlikely that either fomite

This study comprehensively investigated the impact of indoor carbon dioxide (CO2) concentration on sleep quality. Three experimental conditions (800, 1900, 3000 ppm) were created in chambers decorated as bedroom and other environmental parameters that may influence the sleep quality were under strict control. Sleep quality of 12 subjects (6 men and 6 women) was monitored for 54 consecutive days through

The intensity, frequency, duration, and contribution of distinct PM2.5 sources in Asian households have seldom been assessed; these are evaluated in this work with concurrent personal, indoor, and outdoor PM2.5 and PM1 monitoring using novel low‐cost sensing (LCS) devices, AS‐LUNG. GRIMM‐comparable observations were acquired by the corrected AS‐LUNG readings, with R2 up to 0.998. Twenty‐six non‐smoking

Indoor settled dust may result in substantial human exposure to chemicals, especially by ingestion following hand‐to‐mouth or hand‐to‐object‐to‐mouth contact. As with other environmental media related to exposure, dust may thus be subject to regulation. An international scientific workshop was convened in Paris in September 2019 firstly to assess the relevance for public health of setting guidelines

Increased outdoor concentrations of fine particulate matter (PM2.5) and oxides of nitrogen (NO2, NOx) are associated with respiratory and cardiovascular morbidity in adults and children. However, people spend most of their time indoors and this is particularly true for individuals with chronic obstructive pulmonary disease (COPD). Both outdoor and indoor air pollution may accelerate lung function loss

The aim of this study was to explore the association between the building‐related occupants’ reported health symptoms and the indoor pollutant concentrations in a sample of 148 office rooms, within the framework of the European OFFICAIR research project. A large field campaign was performed in 37 office buildings among eight countries, which included (a) 5‐day air sampling of volatile organic compounds

In this study, fifteen participants were exposed to different carbon dioxide (CO2) concentrations in an enclosed environmental chamber to investigate the potential effects of elevated CO2 concentrations on human vigilance and sentiment. The psychomotor vigilance test (PVT), the Karolinska Sleepiness Scale (KSS), and the Positive and Negative Affect Schedule (PANAS) were measured before and after each

With an increasing use of indoor disinfectants such as chlorine (Cl2) and hypochlorous acid, a convenient sampler for estimating exposure to oxidants, such as effective chlorine, is necessary. Here, we developed a personal passive air sampler (PPAS) composed of a redox dye, o‐dianisidine, in a polydimethylsiloxane (PDMS) sheet. o‐Dianisidine readily reacts with gaseous oxidants generated by bleach

Respiratory microbiome is an understudied area of research compared to other microbiomes of the human body. The respiratory tract is exposed to an array of environmental pollutants, including microbes. Yet, we know very little about the relationship between environmental and respiratory microbiome. The primary aim of our study was to compare the mycobiomes and bacteriomes between three sample types

Bioaerosol concentrations in residential buildings located in the Northeastern US have not been widely studied. Here, in 2011‐2015, we studied the presence and seasonal variability of culturable fungi and bacteria in three multi‐family apartment buildings and correlated the bioaerosol concentrations with building ventilation system types and environmental parameters. A total of 409 indoor and 86 outdoor

We conducted a randomized trial of portable HEPA air cleaners with pre‐filters designed to also reduce NH3 in non‐smoking homes of children age 6‐12 with asthma in Yakima Valley (Washington, USA). Participants were recruited through the Yakima Valley Farm Workers Clinic asthma education program. All participants received education on home triggers while intervention families additionally received two

Building ventilation is important for occupants’ health. There are few studies of associations between home ventilation and occupant's health in China. During 2013‐2016, we measured ventilation in 399 homes in Tianjin and Cangzhou, China, and surveyed the health history of children. Ventilation rates were measured using mass balance of occupant generated CO2. The associations of home ventilation with

Heterogeneous surface reactions play a key role in the chemistry of the indoor environment because of the large indoor surface‐to‐volume ratio. The presence of photocatalytic material in indoor paints may allow photochemical reactions to occur at wavelengths of light that are present indoors. One such potential reaction is the heterogeneous photooxidation of NO to HONO. NO(g) is commonly found indoors

Indoor air quality (IAQ) in classrooms has a significant impact on children's academic performance, health, and well‐being; therefore, understanding children's perception of IAQ is vital. This study investigates how children's perception of IAQ is affected by environmental variables and thermal sensation. In total, 29 naturally ventilated classrooms in eight UK primary schools were selected and 805

Harmful emissions including particulates, volatile organic compounds, and aldehydes are generated during three‐dimensional (3D) printing. Ultrafine particles are particularly important due to their ability to penetrate deep into the lung. We modeled inhalation exposure by particle size during 3D printing. A total of six thermoplastic filaments were used for printing under manufacturer's recommended

Recently, studies suggest that the average indoor temperature is typically >30°C and that the maximum temperature can reach 37.5°C in hot‐humid areas. However, the effects caused by increasing the humidity at high indoor temperatures are not clear. In this study, twelve female and twelve male subjects were exposed to different operative temperature (26.6, 30.6, and 37.4°C) and relative humidity (50%

Human activity is known to leave significant effects on indoor airflow patterns. These patterns are carefully designed for many facilities such as cleanrooms, pharmaceutical settings, and healthcare environments, where human‐induced wakes contribute to the transport of contaminants. Therefore, the knowledge about these wakes as it relates to indoor air quality is critical. As a result, a series of

One of the main modes of transmission and propagation of COVID‐19 (SARS‐CoV‐2) is the direct contact with respiratory droplets transmitted among individuals at a certain distance. There are indoor spaces, such as dwellings, in which the transmission risk is high. This research aims to record and analyze risk close contacts in this scope, experimentally assessing the effectiveness of using electronic

Exhaled jets from an infected person are found to be locked at a certain height when thermal stratification exists in rooms, causing a potential high risk of disease transmission. This work is focused on the theoretical analysis of the dynamic characteristics of human speech droplets and the residual droplet nuclei in both thermally uniform and stratified environments. Results show that most droplets

The use of electronic cigarettes (e‐cigarettes), electronic shishas (e‐shishas), and new “smokeless” tobacco products as substitutes for the traditional tobacco cigarette, and as a lifestyle product, has increased significantly in recent years. Several studies showed that the consumption of e‐cigarettes causes the release of undesired substances, which might affect indoor air quality. Therefore, the

Effects of noise on people depend on sound level but also on other sound properties. A systematic comparison of the stress effects of speech and noise with the same frequency content is missing. This study compared stress reactions under sound conditions speech (sound level 65 dB LAeq), noise (65 dB), and silence (35 dB), all having similar relative frequency contents. Fifty‐nine participants were