Size distribution of airborne particles in animal houses

Abstract

The concentration and size distribution of airborne particles were measured inside and outside typical animal houses such as broilers, broiler breeders (both floor housing with litter); layers (floor housing system and aviary housing system); turkeys (floor housing with litter), pigs: fattening pigs (traditional houses, low emission houses with dry feed, and low emission houses with wet feed), piglets, sows (individual and group housing); cattle (cubicle house), and mink (cages).  Using an aerosol spectrometer, particles were counted and classified into 30 size classes (total range: 0.25 – 32 µm).  Particles were measured on for two days, one in spring and the other in summer, in two of each species/housing combination during 30 min inside and outside the animal house.  Outside temperature and relative humidity were also measured.  Particle counts in the different size classes were generally higher in poultry houses than in pig houses, and counts in pig houses were generally higher than those in cattle and mink houses.  The particle counts in animal houses were highest (on average 87%) in the size classes  <1.0 μm, while particle mass was highest in size classes >2.5 μm (on average 97%).  Most particles outside were in the size class <1.0 μm (99% in counts).  Mean count median diameter (CMD) of particles inside the animal houses ranged from 0.32 to 0.59 μm, while mean mass median diameter (MMD) ranged from 3.54 to 12.4 μm.  Particle counts in different size fractions were highly correlated, with correlation coefficients varying from 0.69 to 0.98; higher coefficients were found for the closer size ranges.  Although particle counts in different size ranges varied greatly, for all particle classes, except the particles in the 0.25 – 1.0 µm range, the most variation could be accounted for by species/housing combination and outside temperature and relative humidity.  It should be recognized that the measurements were done during short periods of the day and only during the spring and summer period.

Keywords: particle size distribution, animal houses, CMD, MMD, temperature, relative humidity