Assessing Indoor Air Quality and Ventilation to Limit Aerosol Dispersion—Literature Review

Abstract

The COVID-19 pandemic highlighted the importance of indoor air quality (IAQ) and ventilation, which researchers have been warning about for years. During the pandemic, researchers studied several indicators using different approaches to assess IAQ and diverse ventilation systems in indoor spaces. To provide an overview of these indicators and approaches in the case of airborne transmission through aerosols, we conducted a literature review, which covered studies both from before and during the COVID-19 pandemic. We searched online databases for six concepts: aerosol dispersion, ventilation, air quality, schools or offices, indicators, and assessment approaches. The indicators found in the literature can be divided into three categories: dose-, building-, and occupant-related indicators. These indicators can be measured in real physical spaces, in a controlled laboratory, or modeled and analyzed using numerical approaches. Rather than organizing this paper according to these approaches, the assessment methods used are grouped according to the following themes they cover: aerosol dispersion, ventilation, infection risk, design parameters, and human behavior. The first finding of the review is that dose-related indicators are the predominant indicators used in the selected studies, whereas building- and occupant-related indicators are only used in specific studies. Moreover, for a better understanding of airborne transmission, there is a need for a more holistic definition of IAQ indicators. The second finding is that although different design assessment tools and setups are presented in the literature, an optimization tool for a room’s design parameters seems to be missing. Finally, to efficiently limit aerosol dispersion in indoor spaces, better coordination between different fields is needed.

Enhanced Indoor Air Quality Dashboard Framework and Index for Higher Educational Institutions

“…On the other hand, indoor air quality indices lack the standardization seen in ambient air quality measures. Efforts are frequently tailored to specific building types, occupancy rates, and local pathogens [57][58][59][60]. Parameter selection for these indices is often contingent upon pollutant concentrations relevant to the building's activities or specific local pollutants.…”

“…Parameter selection for these indices is often contingent upon pollutant concentrations relevant to the building's activities or specific local pollutants. Moreover, such IAQ indices are not restricted to IAQ parameters alone [59]. A recent example from the literature presents an Indoor Environmental Quality index, which includes thermal comfort, acoustic comfort, and illumination levels [58].…”

Indoor Climate Monitoring in Office Buildings—Comparative Analysis of Two Office Buildings without Air Conditioning

“…The worldwide pandemic has raised the interested in CO 2 traffic lights to stimulated window ventilation. Increased ventilation reduces the aerosol content in the room air [25]. Aerosol contamination was found to be the major path of infection in rooms occupied by multiple persons.…”

UVC-Mirror for effective pathogens inactivation in air ducts

“…The recent SARS-CoV-2 (COVID-19) has drawn much attention to this issue due to its devastating health, social, and economic impacts worldwide. Before the COVID-19 pandemic, several studies showed the relationship between airborne transmission and indoor ventilation [17]. The emergence of Severe Acute Respiratory Syndrome (SARS) outbreak in 2002-03, the H1N1 influenza epidemic in 2011 and the threat of a different influenza pandemic, the Middle East Respiratory Syndrome (MERS) outbreak in 2012, the global prevalence of tuberculosis serve as timely reminders of the substantial risk posed to human health by airborne infectious diseases [17], [18], [19].…”

“…In indoor spaces, there are many potential sites for spreading pathogens, including sick/infected persons, contaminated indoor air, and the threat of recirculated contaminated air through the heating, ventilation, and air conditioning (HVAC) systems. Different studies indicate HVAC, fans, humidifiers, etc., as the major sources of propagation and spread of microorganisms in indoor buildings [5], [11], [17], [22].…”