Health-related aerosol particle studies, respiratory tract deposition and indoor source identification

Aerosol particles have, since Classical Antiquity, been linked to adverse effects on human health. It is estimated that the particles in urban air pollution causes 100 000 deaths in Europe each year, whereof 5 000 in Sweden. These figures do not include the outcomes of indoor sources or smoking, which shortens the lives of millions of people worldwide. Many studies indicate that fine particles (<2.5 μm) are to be more toxic than larger ones. Especially the ultrafine particles (<0.1 μm), typically originating from combustion sources, have been of much concern. Part of the reason could be their high probability to deposit deep into the lung once inhaled. A novel method has been developed for determination of fine and ultrafine particle deposition in the respiratory tract. It is designed to be used on larger groups of human subjects in exposure studies and in typical ambient and indoor environments. The method is demonstrated to have a precision in the determined deposition fraction (DF) of 0.02–0.08 and to be sensitive enough to quantify differences between breathing patterns and between hygroscopic and hydrophobic aerosols. The results for hydrophobic particles are in agreement with the well-established ICRP 66 model. The developed instrument was used to investigate the influence of hygroscopicity (the ability to grow by uptake of water), exercise level, gender and intersubject variability on size-dependent deposition of fine and ultrafine particles (12-320 nm) during spontaneous breathing. DF was measured for 29 healthy adults (20 men, 9 women) in four exposure situations; rest and light exercise with both hydrophobic (Di-Ethyl-Hexyl-Sebacate) and hygroscopic (NaCl) particles. DF was 2-4 times higher for the hydrophobic ultrafine particles than for the hygroscopic. DF of hygroscopic ultrafine particles could be estimated by calculating their equilibrium size at 99.5% relative humidity. The differences in average DF due to exercise level and gender were essentially insignificant, but the minute ventilation was 4-fold higher during exercise and 18%-46% higher for the males. Consequently the deposited dose of particles was 4-fold higher during exercise and considerably increased for the male subjects. Some individuals generally had a high DF in all four sessions. To assist the work for healthy indoor environments, a methodology for identifying sources to particles larger than 0.5 μm was designed and applied in a study of three houses in southern Sweden. The methodology includes (1) visual inspection in order to identify deposited particles and potential sources, (2) measurement of airborne particles at different positions in a building with simultaneous logging of activities and (3) isolation of potential sources in a test chamber for controlled characterizations of the generated particles. The results show that source identification is facilitated by knowledge of concentration variations between different rooms, real-time measurements together with activity reports and information on particle characteristics that are comparable with results from laboratory simulations. Major particle emissions from textile handling, likely due to detergent zeolite residues, were found in the studied houses

Characteristics of SARS-CoV-2-containing aerosols in hospital corridors

The aim of this work is to investigate the presence of airborne SARS-CoV-2 in corridors of infection wards, and gain more detailed size information of SARS-CoV-2-containing aerosols. Associations between SARS-CoV-2 presence and relative humidity and/or temperature in the facilities is also explored

Airborne SARS-CoV-2 RNA collected during childbirth and autopsy

Airborne SARS-CoV-2 is considered to play a major role in covid-19 transmission, and several studies have reported its presence in hospital environments, including corridors, patient rooms, cohort rooms and ICUs (Dinoi et al., 2022). The risk of airborne virus have been associated with a number of factors, such as low ventilation, high patient viral load and in some cases, certain medical procedures.However, specific medical situations still deserve further investigation. One such situation of interest is childbirth, as respiratory emissions, which could contain virus, are increased due to heavy breathing during labor. Another situation with potential risk for airborne SARS-CoV-2 is autopsy.The aim of the current study was to further explore the presence of airborne SARS-CoV-2 RNA during childbirth and autopsy.The results in this study can increase our understanding about the risk of covid-19 transmission by aerosols at delivery wards and during autopsy, even though the sample material is small. Reports of airborne SARS-CoV-2 in hospital environments contribute to improving guidelines for protective equipment for healthcare personnel working with such patients

SARS-CoV-2 in size-fractionated aerosols from hospital corridors and relations to the indoor environment

The aim of the current study was to evaluate the presence of airborne virus, specifically SARS-CoV-2, in infection ward corridors, and the size distribution of the virus-containing aerosols. Associations between virus presence and relative humidity and/or temperature in the facilities was also investigated

Airborne SARS-CoV-2 during childbirth

Airborne SARS CoV 2 is considered to play a major role in covid 19 transmission, and has been found in several hospital environments. There is a need to investigate the presence of airborne SARS CoV 2 in other hospital areas than traditional infectious disease wards. The results from the present study can contribute to a better understanding of the risk of covid 19 transmission by aerosols at delivery wards