What is the relationship between indoor air quality parameters and airborne microorganisms in hospital environments? A systematic review and meta‐analysis

Abstract

Airborne microorganisms in hospitals have been associated with several hospital‐acquired infections (HAIs), and various measures of indoor air quality (IAQ) parameters such as temperature, relative humidity, carbon dioxide (CO2), particle mass concentration, and particle size have been linked to pathogen survival or mitigation of pathogen spread. To investigate whether there are quantitative relationships between the concentration of airborne microorganisms and the IAQ in the hospital environment. Web of Science, Scopus and PubMed databases were searched for studies reporting airborne microbial levels and any IAQ parameter(s) in hospital environments, from database inception to October 2020. Pooled effect estimates were determined via random‐effects models. Seventeen of 654 studies were eligible for the meta‐analysis. The concentration of airborne microbial measured as aerobic colony count (ACC) was significantly correlated with temperature (r = 0.25 [95% CI = 0.06–0.42], p = 0.01), CO2 concentration (r = 0.53 [95% CI = 0.40–0.64], p ˂ 0.001), particle mass concentration (≤5 µg/m3; r = 0.40 [95% CI = 0.04–0.66], p = 0.03), and particle size (≤5 and ˃5 µm), (r = 0.51 [95% CI = 0.12–0.77], p = 0.01 and r = 0.55 [95% CI = 0.20–0.78], p = 0.003), respectively, while not being significantly correlated with relative humidity or particulate matter of size >5 µm. Conversely, airborne total fungi (TF) were not significantly correlated with temperature, relative humidity, or CO2 level. However, there was a significant weak correlation between ACC and TF (r = 0.31 [95% CI = 0.07–0.52], p = 0.013). Although significant correlations exist between ACC and IAQ parameters, the relationship is not definitive; the IAQ parameters may affect the microorganisms but are not responsible for the presence of airborne microorganisms. Environmental parameters could be related to the generating source, survival, dispersion, and deposition rate of microorganisms. Future studies should record IAQ parameters and factors such as healthcare worker presence and the activities carried out such as cleaning, sanitizing, and disinfection protocols. Foot traffic would influence both the generation of microorganisms and their deposition rate onto surfaces in the hospital environment. These data would inform models to improve the understanding of the likely concentration of airborne microorganisms and provide an alternative approach for real‐time monitoring of the healthcare environment.

Photoelectrochemical oxidation assisted air purifiers; perspective as potential tools to control indoor SARS-CoV-2 Exposure

“…The hospital central HVAC system and MERV-rated filters is a generalized approach toreduce bacteria and fungi in the air, but other airborne microbes and toxins can exist in localized indoor environment at very high levels. This may be due to the pathogens or pollutants carried by the patient or hospital workers, those disturbed by movement in the room, or otherwise those that are not effectively filtered by the central HVAC system [ 21 , 22 ]. Patients and hospital workers may be at a higher risk due to pathogenic complications in the air.…”

“…Indoor air quality is always a concern to maintain according to international standards but not well highlighted due to lack of awareness and widespread technology. Recent viral infection outbreaks (COVID-19 pandemic) not only forced health agencies globally to develop better medical infrastructure and new policies to deal with infectious diseases but also made the general population understand the value of clean air [21] , [22] , [23] . As a result, the need for virus-free indoor air to avoid virus exposure raised the demand of investigating new technologies which can clean the air in reduced form factors, i.e., with more advantages, affordability, and acceptability.…”

“…Besides increasing investment and health benefits, the available air purifiers constantly show various shortcomings such as limited filter efficiency, high power consumption, and inefficacy in larger premises [21] . At the same time, most of these systems only trap pollutants, PM (mainly PM 2.5/10.0 ) and VOCs.…”

Inanimate Surfaces and Air Contamination with Multidrug Resistant Species of Staphylococcus in the Neonatal Intensive Care Unit Environment

“…Active air sampling was performed; however, the movements were not recorded. Increased people-traffic and a positive correlation with active air sampling at higher bed occupancy levels is also unsurprising [ 27 ]. These results are worrying, because the air conditioning system at the NICU is central, and there are many invasive procedures, performed in the unit, such as bladder catheterization, CVC insertion, PICC, and umbilical venous catheterization.…”

Preparation, Characterization and Antimicrobial Properties of Nanosized Silver‐Containing Carbon/Silica Composites from Rice Husk Waste

“…780 million people do not have access to clean water on a daily basis (status 2014), [32] while, on the other hand, air pollution and airborne pathogens are extremely problematic, like recently demonstrated by the devastating COVID-19 pandemic, [33] in both private households and indoor working places, [34] as well as in professional healthcare environments. [35] Fortunately, AgNPs can be and are applied against pathogens in water or on surfaces as well as against airborne pathogens. [36] Moreover, since ancient times, the use of silver has not been associated with health risks (when not used in disproportionate amounts).…”