Indoor distribution characteristics of airborne bacteria in pig buildings as influenced by season and housing type.

OBJECTIVE: A concentration of airborne bacteria generated from swine houses is recognized to be relatively higher than other work places and it is essential to optimally manage it to prevent farmers' respiratory diseases. This study was conducted to assess the distribution characteristics of airborne bacteria in swine houses located at South Korea. METHODS: A total 27 pig buildings of the enclosed type operated with mechanical ventilation system by a side wall fan and deep-pit manure system with slats were surveyed. Air samples were collected at 1.0 m above the middle floor in pig housing room. A six-stage viable particulate cascade impactor was used to identify the distribution of the sizes of particles in diameter. RESULTS: Seasonal mean levels of airborne bacteria in the housing rooms of gestation/farrowing pigs, nursery pigs and growing/fattening pigs were 3,428(±1,244) colony forming unit (cfu)/m3, 8,325(±3,209) cfu/m, and 13,254(±6,108) cfu/m3 for spring; 9,824(±2,157) cfu/m3, 18,254(±5,166) cfu/m3, and 24,088(±9,274) cfu/m3 for summer; 1,707(±957) cfu/m3, 4,258 (±1,438) cfu/m3, and 8,254(±2,416) cfu/m3 for autumn; and 2,322(±1,352) cfu/m3, 6,124(±1,527) cfu/m3 and 12,470(±4,869) cfu/m3 for winter, respectively. CONCLUSION: Concentrations of airborne bacteria according to pig housing type were highest in growing/fattening housing room followed by nursery housing room and gestation/farrowing housing room. In terms of seasonal aspect, the pig building showed the highest levels of airborne bacteria in summer followed by spring, winter and autumn. The respirable airborne bacteria which are ranged between 0.6 and 4.7 µm accounted for approximately 60% compared to total airborne bacteria regardless of pig housing type.

Assessment of Korean farmer's exposure level to dust in pig buildings.

The purpose of the study was to assess Korean farmer's exposure level to dust in pig buildings and dust emissions by investigating airborne concentrations of total and respirable dust. Five main types of pig buildings operating currently in Korea were selected. For area air sampling, 30 sites per each building type were visited during spring (March-May) and autumn (September-November) seasons. For personal air sampling, concentrations of total and respirable dust were measured for 2-3 hours, during cleaning the pig building before the end of the daily shift, by attaching air sampling equipment near to the farmer's breathing zone. Measurement were taken for 8 hours, e.g. average daily work time (09:00-17:00), at 0.5 m above the floor at three locations on the central alley in the pig building. Emission rates of total and respirable dust were estimated by multiplying the mean concentration of total and respirable dust measured near the air outlet by the mean ventilation rate, and expressed either per area or per pig of live weight. The ranges of farmer's exposure level to total dust and respirable dust in the pig buildings were estimated as 0.6-6.7 mg m(-3) and 0.3-3.5 mg m(-3), respectively. The pig buildings operated with a deep-litter bed system showed the highest dust level while the naturally ventilated pig buildings with slats represented the lowest dust level (p<0.05). Emission rates ranged from 35-400 mg h(-1) m(-2) for total dust and from 4-40 mg h(-1) m(-2) for respirable dust, respectively, indicating a similar pattern for the distribution of exposure level. Korean farmers' exposure level to dust in all the pig buildings investigated was below the exposure limit value equal in Korea equal to 10 mg m(-3), while it exceeded the threshold limit values (TLVs) established in other developed countries. In comparison with previous studies performed in other countries, mean exposure level in the pig buildings of Korea was generally lower for total dust and higher for respirable dust based on the area sampling method.

Odor reduction rate in the confinement pig building by spraying various additives.

The objective of this on-site experiment was to evaluate and compare the effectiveness of currently utilized various additives, i.e. tap water, salt water, digested manure, microbial additive, soybean oil, artificial spice and essential oil, to reduce odor emissions from the confinement pig building. Odor reduction rates were evaluated with respect to sensual odor (odor concentration index, odor intensity and odor offensiveness) and odorous compounds (ammonia and sulfuric odorous compounds). Of the additives investigated in this study, salt water, artificial spice and essential oil had a positive effect on reducing odor generation. The effectiveness of salt water was only observed on ammonia, showing the reduction rates as a function of time (t=immediately, 1h, 3h, 5h, and 24h after spraying) were 0.1%, 20%, 36%, 11% and 0.2% as compared to initial level before spraying. The odor intensity and offensiveness were lessened by spraying artificial spice and essential oil of which maximum reduction rates ranged from 60% to 80%. Additionally, the essential oil had a significant effect on reducing sulfuric odorous compounds for 24h after spraying, which implicates that it functioned as not only a masking agent but also as an antimicrobial agent.

Effect of manual feeding on the level of farmer's exposure to airborne contaminants in the confinement nursery pig house.

The objective of the study is to demonstrate an effect of manual feeding on the level of farmer's exposure to airborne contaminants in the confinement nursery pig house. The levels of all the airborne contaminants besides respirable dust, total airborne fungi and ammonia were significantly higher in the treated nursery pig house with feeding than the control nursery pig house without feeding. Although there is no significant difference in respirable dust and total airborne fungi between the treatment and the control, their concentrations in the treated nursery pig house were also higher than the control nursery pig house. The result that the level of ammonia in the treated nursery pig house is lower than the control nursery pig house would be reasoned by the mechanism of ammonia generation in the pig house and adsorption property of ammonia to dust particles. In conclusion, manual feeding by farmer increased the exposure level of airborne contaminants compared to no feeding activity.

Effect of ventilation rate on gradient of aerial contaminants in the confinement pig building.

The principal aim of this study was to compare the aerial contaminants concentrations between the levels of ventilation rate and determine the variation pattern of aerial contaminants affected by the ventilation rate. As a result, there was not significant difference in total dust and total airborne microorganisms among three levels of ventilation rate (P>0.05) whereas the increased ventilation rate lowered the levels of respirable dust and gaseous compounds (P<0.05). Based on the results, it was concluded that the suspended gases in the confinement pig building generally followed the air streamline formed by the ventilation whereas the ventilation rate had little effect on the gradient of particulates, especially total dust, due to gravity generated by their size and weight. The findings that the concentrations of total airborne microorganisms were not also significantly different among the ventilation rates could be explained in terms of the fact that airborne microorganisms are easily adsorbed on the surface of dust particle.

Influence of extreme seasons on airborne pollutant levels in a pig-confinement building.

Understanding airborne pollutant levels in a pig-confinement building in seasons with extreme weather (ie, summer and winter) is important for managing air quality, which affects the health of farmers and others in the neighboring environment. The authors evaluated airborne pollutants-total dust, total airborne bacteria, and total airborne gram-negative bacteria-which had higher concentrations in summer than in winter, and concentrations of respirable dust, gaseous pollutants, and total airborne fungi, which were lower in summer than in winter. The authors found significant differences between summer and winter measurements for respirable dust and gaseous pollutants (p < .05). Total dust was positively correlated with bioaerosols and ammonia (p < .05), whereas respirable dust was positively correlated with odor concentration index (p < .05) and hydrogen sulfide (p < .01).