Dust generation and microbiological air quality with different bedding materials in a horse stable

Introduction
The stable climate is of paramount importance to the respiratory health of horses
Methods
Four bedding materials (deep straw mattress, daily cleaned straw, dedusted soft wood granulate and bio-compost) were compared with respect to the amount of airborne particular matter (PM2,5 and PM10) at two different heights in a horse box (50 cm and 120 cm from the ground) and to the microbiological air quality of the air as colony forming units per cubic meter, (CFU/m3) of total bacteria, mold spores, total actinomycetes and the proportion of thermophilic actinomycetes. The bedding materials were tested for 10 days each. Dust was recorded continuously with two SDS011 sensors and microbiological air sampling was performed on days 1, 5 and 10 using an air sampling system (MBASS30v3, Holbach GmbH, Germany). The air temperature and humidity as well as the work in the barn were considered in the statistical analysis (R Core Team 2019, level of significance p<0.05).
Results & Discussion
The differences between the bedding materials, in terms of dust were considered significant (p<0.001), except for PM10 between soft wood granulate and bio-compost (p>0.05). The soft wood granulate presented the lowest values in terms of total germs (average 3'552 CFU/m3), total actinomycetes (average 528 CFU/m3) and the proportion of thermophilic actinomycetes (average 176 CFU/m3). The lowest values in mold spores were found with the deep layer straw litter (average 1'776 CFU/m3). The highest values were found with bio-compost for all types of germs (average: total germs 21'097 CFU/m3; mold spores 38'860 CFU/m3; total actinomycetes 4'440 CFU/m3, the proportion of thermophilic actinomycetes 777 CFU/m3). Airborne particular matter (PM 2.5 and PM 10) and microbiological air quality were not correlated (r = 0.01).
Clinical Relevance
The type and management of bedding influences microbiological air quality and thus lung health