Analysis of airborne dust concentration in a naturally-ventilated broiler house

Abstract

The enhancement in the productivity of the Korean poultry industry has had a positive effect on its competitiveness in exports. However, the expansion and overproduction for providing the needed amount of supply increase the rearing density and create an inferior environment within the broiler houses. Especially, a crowded rearing environment generates a vulnerable dust environment within the broiler houses, which acts as a factor for inducing respiratory diseases in the broilers and workers, such as bronchitis and occupational asthma and so on. Despite such harms, however, not only is the periodic monitoring and study of the dust environment within broiler houses unsatisfactory but also the legal regulations for the permissible standards within them yet to be established. Thus, this study has conducted a periodic monitoring of TSP, PM10 and inhalable and respirable dust in a naturally-ventilated broiler house according to the season and the age and activity of the broilers, while assessing the air quality within the broiler house according to the threshold limit as proposed by Donham et al. (2000) and CIGR (1994). When the TSP and PM10 were measured at different points of time, different concentrations were found across the seasons: the average dust concentration was found to be highest in the winter, followed by autumn and summer. The difference between the concentration of PM10 and that of TSP was relatively small, and the ratio of PM10 to TSP increased with the age of birds, implying that the rate of production of PM10 increases with the age of birds. Also, it is thought that most of the dust at the height of the respiratory system of the workers has the size that is either same as or smaller than that of PM10. When the concentrations of inhalable and respirable dust were measured across the seasons, different schematic amounts of ventilation were found to contribute to a considerable level of difference in the dust concentration in different seasons. When the activity of the broilers increased by the entry and exit of the workers to manage in the broiler house, inhalable dust increased by up to 769.6% (28-day old, summer) and respirable dust by up to 882.4% (28-day old, summer) compared to when the broilers activity were stable. Such differences significantly increased with the age of broilers (p < .05). Also, the dust concentrations were higher than the threshold limit for human lung function as proposed by Donham et al. (2000) and the threshold limit for the lung function of broilers as proposed by CIGR (1994) when the entry and exit of the workers induced the activity of the broilers. Especially, the concentration of respirable dust was over the threshold limits even when the broilers were stable, indicating that a dust environment that is harmful for the workers and the broilers had already been created within the broiler house. Thus, protective devices such as masks should be recommended when working within broiler houses. A physicochemical analysis of the dust collected from the air confirmed N, K, F, S, Mg, Cl and Na as its components. Particularly, it seems that airborne dust within a broiler house is largely affected by the feathers of broilers and the bedding material. A correlational analysis between the dust concentrations and the internal and external environmental parameters found a strong negative correlation when the broilers were young. As they grew older, however, the correlation with the external environment mostly disappeared, while there was a strong negative correlation with the internal temperature. This implies that the appropriate rearing temperature decreases as the broilers grow older, and that the amount of dust produced by the older broilers, including feathers and skin fragments, may have an effect on the dust concentration. This study provides preliminary data for the assessment of air quality within a naturally-ventilated broiler house based on its dust concentration and investigate the sources of the dust. The results of this study is hoped to help with further studies for dust reduction within broiler houses by aiding in the estimation of the main sources of dust and the control of dust production from the sources.