ObjectivesExposure to environments rich in microorganisms such as farms has been shown to protect against the development of childhood asthma and allergies. However, it remains unclear where, and how, farm and other rural children are exposed to microbes. Furthermore, the composition of the microbial flora is poorly characterised. We tested the hypothesis that farm children are exposed indoors to substantial levels of viable microbes originating from animal sheds and barns. We also expected that environmental microbial flora on farms and in farm homes would be more complex than in the homes of rural control children.MethodsDust samples were collected using passive samplers in the bedrooms of the following groups of children in rural Bavaria, Germany: (i) those living on farms (n=144), (ii) those regularly exposed to farm environments but not living on farms (n=149) and (iii) those never visiting farms (n=150). For farm children, additional samples were collected in animal sheds and barns. All samples were subjected to fungal and bacterial culturing.ResultsDetectable levels of microorganisms were more often found in samples taken from farm dwellings than from other homes. Farm dwellings also showed higher microbial levels. Microbial counts of farm dwelling samples correlated with the counts in corresponding animal sheds and barns.ConclusionsMicroorganisms are transported from animal sheds and barns into farm dwellings. Therefore, children living in these environments are exposed when indoors and when visiting animal sheds and barns. Indoor exposure may also contribute to the protective effect of the farm environment.
There is an ongoing debate on airborne transmission of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) as a risk factor for infection. In this study, the level of SARS-CoV-2 in air and on surfaces of SARS-CoV-2 infected nursing home residents was assessed to gain insight in potential transmission routes. During outbreaks, air samples were collected using three different active and one passive air sampling technique in rooms of infected patients. Oropharyngeal swabs (OPS) of the residents and dry surface swabs were collected. Additionally, longitudinal passive air samples were collected during a period of 4 months in common areas of the wards. Presence of SARS-CoV-2 RNA was determined using RT-qPCR, targeting the RdRp- and E-genes. OPS, samples of two active air samplers and surface swabs with Ct-value ≤35 were tested for the presence of infectious virus by cell culture. In total, 360 air and 319 surface samples from patient rooms and common areas were collected. In rooms of 10 residents with detected SARS-CoV-2 RNA in OPS, SARS-CoV-2 RNA was detected in 93 of 184 collected environmental samples (50.5%) (lowest Ct 29.5), substantially more than in the rooms of residents with negative OPS on the day of environmental sampling (n = 2) (3.6%). SARS-CoV-2 RNA was most frequently present in the larger particle size fractions [>4 μm 60% (6/10); 1–4 μm 50% (5/10); <1 μm 20% (2/10)] (Fischer exact test P = 0.076). The highest proportion of RNA-positive air samples on room level was found with a filtration-based sampler 80% (8/10) and the cyclone-based sampler 70% (7/10), and impingement-based sampler 50% (5/10). SARS-CoV-2 RNA was detected in 10 out of 12 (83%) passive air samples in patient rooms. Both high-touch and low-touch surfaces contained SARS-CoV-2 genome in rooms of residents with positive OPS [high 38% (21/55); low 50% (22/44)]. In one active air sample, infectious virus in vitro was detected. In conclusion, SARS-CoV-2 is frequently detected in air and on surfaces in the immediate surroundings of room-isolated COVID-19 patients, providing evidence of environmental contamination. The environmental contamination of SARS-CoV-2 and infectious aerosols confirm the potential for transmission via air up to several meters.
Although the workers were exposed to a relatively low mean dust level, the microbial exposure was high. Furthermore, the exposure levels of microbial components varied between workplaces although the dust levels were similar. We therefore recommend that exposure levels at different workplaces should be assessed separately and a task-based assessment should be done for detailed evaluation of efficient dust-reducing measures. The microbial content and knowledge of health effects of the microbial components should be considered in health risk evaluations of these workplaces.
SynopsisIn dit rapport worden twee deelonderzoeken beschreven. In het eerste deel (A) zijn metingen verricht van stof en endotoxinen in het stof bij twee stallen voor leghennen, twee stallen voor vleeskuikens en twee stallen voor vleesvarkens. Op grond van deze meetgegevens is in het tweede deel (B) van dit onderzoek de endotoxineconcentraties in de omgeving van een aantal fictieve stallen berekend. Voor deze specifieke toepassing is een variant van het Nieuw Nationaal Model verder verfijnd. Ook zijn de concentraties van fijn stof en geur berekend voor deze stallen m.b.v. de verspreidingsmodellen die daarvoor in vergunningsverlening worden gebruikt. Voor elk van deze drie componenten en voor elk van de fictieve stallen is de afstand bepaald tot waar overschrijding plaatsvindt van de bijbehorende grenswaarde (de zogenaamde overschrijdingsafstand). Voor endotoxinen is hierbij de door de Gezondheidsraad voorgestelde grenswaarde voor endotoxinen van 30 endotoxine eenheden per kubieke meter gehanteerd. Uit de berekeningen blijkt dat bij pluimveestallen de overschrijdingsafstand voor endotoxinen in het merendeel van de doorgerekende scenario's groter is dan voor fijn stof en geur. Bij deze stallen lift de bescherming tegen te hoge endotoxineconcentraties in de buitenlucht dus niet automatisch mee op de bestaande toetsingskaders voor fijn stof en geur. AbstractThis report describes a study carried out in two parts. In the first part (A), measurements of dust and endotoxins in this dust were carried out at two houses for laying hens, two houses for broilers and two houses for fattening pigs. On the basis of these measurement data, the endotoxin concentrations were calculated in the vicinity of a number of fictitious farms in the second part (B). For this specific application, a variant of the New National Model was refined. The concentrations of dust and odour were also calculated for these farms using dispersion models prescribed for this purpose in environmental permit granting procedures. For each of the three components and for each of the fictitious farms, the distance was determined up to where the corresponding limit value is exceeded (the so-called exceedance distance). For endotoxins, the proposed limit value for endotoxins in the ambient air by the Dutch Health Council of 30 endotoxin units per cubic meter was applied. The calculations show that around poultry farms in the majority of modelled scenarios, the exceedance distance for endotoxins is greater than for dust and odour. Thus, around these farms, the existing assessment frameworks for fine dust and odour are not sufficient to provide the desired level of protection against endotoxins. • hoe hoog zijn de endotoxinegehalten in het uitgestoten stalstof, de endotoxineconcentraties in de geventileerde stallucht en de endotoxine-emissies? OmslagfotoDe stofdeeltjes hebben diameters die variëren van zeer klein tot groot. Daarom is een volgende onderzoeksvraag:• hoe zijn de endotoxinen verdeeld over de stofdeeltjes met verschillende groottes?Voor beantwoording v...
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