Pulmonary effects of exposure to pig barn air

Canada is among the top five pork exporters of the world with a total pork export of 970,000 tons in the year 2004, which translates into cash receipts of $4.2 billion in the year 2004 representing a 25% increase over the year 2003. In 2005, Canada had 14.9 million hogs which is an increase of 1.7% over the previous year and the pork export is expected to grow by 2% [1,2]. Currently, pork sector accounts for 30% of total livestock shipments and for 10% of all farm cash receipts in Canadian farm economy. Further, swine farming has provided employment to 10,790 people in Canada [3]. Therefore, swine production is a major component of Canada's agricultural economy. Although the number of pigs has increased but the number of farms has shown a decline to indicate fewer people are working longer shifts on the farms. Now a days, small family operated pig farms are making way for large scale facilities where thousands of pigs are raised in a single facility [4]. Large pig production operations require many full time workers who work 8 hour/day and 5 days/week and thus experience high intensity interrupted exposures to the barn air [5,6]. However, still many workers may work only a few hours every day inside a pig barn. The barn air is very complex and contains organic dust, plant materials (pollen grains, feed grains, hay and silage), animal origin materials (swine dander, hair, urine and pig proteins), microbial components (mite or their parts, bacteria, endotoxin, (1–3) β-D-glucan and fungal spores) and a number of gases such as ammonia, carbon dioxide, hydrogen sulphide and methane [7-9]. Therefore, although modern barns appear cleaner, the air inside these barns still carries toxic molecules which are harmful to the workers [10].Exposure to the toxic molecules in the barn air is a risk factor for the development of chronic respiratory symptoms and lung dysfunction [11]. Respiratory diseases in agricultural farmers are one of the earliest recognized occupational hazards