Relationship between particulate matter and ammonia concentrations in different types of piggeries: bat vs traditional confinements

Nowadays, the intensive swine husbandry is organized and structured to reduce environmental impact, by the set-up of the so called “Best Available Techniques”, that limit gasses emissions using innovative plants, structures and management, through the ventilation system. The adoption of Best Available Techniques (BAT; ILF BREF; 1,2) was addressed mainly to limit ammonia release into atmosphere, from swine and poultry rearing confinements. Indeed, a good air quality, with low concentrations of gasses and dust, in livestock confinements is the basis to guarantee animal health and welfare (3). The studies about the efficiency of the BAT buildings show the high efficiency of these techniques on ammonia reduction, but there are small information on dust concentration containment and its emission into atmosphere. In the present study the efficiency at limiting ammonia and dust concentration and emission was measured in a BAT farrowing room vs a traditional one, in Northeast Italy. For this purpose, three farrowing rooms equipped with BAT number 4.7.3.3, and three conventional rooms with slatted floor on deep pit, each lodging 14 sows, were studied in three different seasons of the year. In each room, identical for design and management, ventilation was managed by the FRCA control unit system (FANCOM EasyFlow, Panningen, The Netherlands). Dust was measured using a Grimm Portable Laser Aerosol Spectrometer Model Mini-LAS 11-R, to evaluate PM10, PM2.5 and PM1, in mass and count, in the facilities. The instrument was placed in the middle of the pen in a protective shell, at a height of 50 cm, at the respiratory apparatus level of pigs. Ammonia concentration was measured using a Gas Badge Pro analyser in 7 different points every 3 days. Dust and ammonia emission was calculated multiplying the pollutant concentration values (ppm for ammonia, converted to mg m-3) and the ventilation rate (m3 h-1). Data were analysed using the ANOVA procedure of SAS (Cary, NC), keeping the room (BAT vs traditional) as experimental unit. The ammonia emitted by the BAT room was lower than that emitted by the reference room, as it was expected, in line with literature (4). Considering the value of 4.680 kg/ap/yr of ammonia emitted by the reference farrowing room of the study, lower than the one indicated by the ILF BREF for the traditional system (8.3 kg NH3/sow/yr), the value of 3.234 kg NH3/sow/yr of ammonia corresponds to reduction of 31 %, in line with the ammonia reduction efficiency of that solution, PM10 (3.59 g/d/LU for BAT and 4.93 g/d/LU for the reference) and PM2.5 (0.32 g/d/LU for BAT and 0.50 g/d/LU for the reference) concentration and emission showed the same trend of ammonia, while PM1, expression of fine dust, did not show significant differences between traditional and BAT rooms (0.11 g/d/LU for BAT and 0.12 g/d/LU for the reference). These results confirm the good efficiency of BAT solutions in livestock farming to reduce atmospheric environmental impact, following a potential interaction between dust and ammonia concentrations in piggeries, with the formation of secondary particulate matter (5).