AIR QUALITY Bioaerosol Sampling in Animal Environments Measuring: Bioaerosols AIR QUALITY EDUCATION IN ANIMAL AGRICULTURE March 2012 Lingjuan Wang Li, Associate Professor Department of Biological and Agricultural Bioaerosols in General Engineering, North Carolina State ioaerosols are particles of biological origin suspended in the air. In outdoor air, University B 1 Otto D. Simmons III, Research Assistant 30 percent of all particles larger than 0.2 µm appear to be of biological origin. Particle sizes and natural background concentrations of bioaerosols have been reported as Professor, Department of Biological and following: Agricultural Engineering, North Carolina State University Table 1. Bioaerosol sizes and concentrations in natural background2. Eileen Fabian Wheeler, Professor, Agricultural Engineering Type of Bioaerosols Size (µm) Concentration (#/m3) The Pennsylvania State University Viruses 0.02-0.3 --- Bacteria 0.3-10 0.5 – 1,000 Fungal Spores 0.5-30 0 – 10,000 This publication discusses Pollen 10-100 1 – 1,000 different samplers that can be As shown in Table 1, bioaerosols cover a wide size range, of which viruses are used for collecting bioaerosols the smallest. Viruses, bacteria, and fungal spores that are capable of causing disease from environmental air and are referred to as pathogens. Some pathogens are specific for certain hosts, like hu- considerations for choosing a mans or animals, while others can infect a wide host range that may include humans as well as animals. Those pathogens capable of infecting both humans as well as suitable sampler. other animals are called zoonotic pathogens. Contents Bioaerosol Classification Bioaerosol Sampling ...............4 Depending upon their biological characteristics, bioaerosols can be classified into Bioaerosol Samplers ...............6 the following types: Biological Analysis ................12 Summary ..............................14 Viruses References ...........................15 Viruses can infect and reproduce only inside a susceptible host cell. As intracel- lular parasites, viruses never replicate on nonliving substrates in the environment. Several facts about viruses include2: eXtension • Naked viruses range in size from 0.02 – 0.3 µm. • Most airborne viruses are part of droplet nuclei or attached to other particles with Air Quality in Animal Agriculture a wide range of sizes. http://www.extension.org/pages/ • Airborne viruses are transmitted by direct contact, or by inhalation of aerosolized 15538/air-quality-in-animal-agriculture viruses. • Aerosolization of viruses may occur by coughing, sneezing, or talking. • Under favorable ambient conditions (temperature, humidity, etc.), most viruses can survive for weeks. Mitigation FS-1 AIR QUALITY EDUCATION IN ANIMAL AGRICULTURE 31 Bacteria Bacteria are single-celled organisms that range in size from 0.3 to10 µm. Several facts about bacteria include2: • Bacteria are generally spherical or rod-shaped. • Bacteria often occur as clusters or chains. Bioaerosols • Under ambient conditions, bacteria colonize water or soil and will be released as aerosols when the water or soil is disturbed. are particles of • In indoor environments, bacteria can survive and colonize in moist environments, biological origin that such as ventilation systems, and are aerosolized by air currents or vibration. are suspended in In addition, bacteria can be classified into two groups based upon their ability to retain crystal violet dye1: environmental air. • Gram-positive bacteria (retain the dye) have cell walls that consist mainly of peptidoglycan, which can cause adverse health effects. • Gram-negative bacteria (don’t retain the dye) have cell walls that contain an outer membrane composed of lipopolysaccharides (endotoxin), lipoprotein, and other complex macromolecules that can cause adverse health effects. Specifically,endotoxins in the outer membrane of Gram-negative bacteria are chemically stable and heat resistant. Endotoxins are released when the bacterial cells are lysed and will maintain their biological activity (i.e., adverse health effects), even after the bacterial cells are no longer viable. Moreover, they are abundant in agricultural environ- ments, with the highest reported airborne endotoxin levels of 2 to 7 µg/m3 in cotton mills and are associated with fecal material in agriculture or wastewater treatment. For comparison, ambient background levels of endotoxins in most outdoor environments are in the subnanogram range. The adverse health effects associated with exposure to endotoxins include fever, malaise, changes in white blood cell counts, and respiratory distress. Fungi Fungi are a unique group of organisms that can occur as single-celled organisms (e.g., yeasts) or as multicellular branching structures. To date, 70,000 of 1.5 million known fungi have been identified and classified2. They are grouped based upon their methods of spore production. Most adverse health effects associated with fungi include allergic reactions and respiratory diseases. Pollen Pollen grains, produced by plants to transmit genetic material, are near spheri- cal particles that range in size from 10 to 100 µm, with most between 25 and 50 µm. Although pollen grains are not in the respirable size fraction (can deposit in the lungs), they may contain allergens that lead to adverse health effects in the upper airways (hay fever). In addition, airborne pollen grains are resistant to environmental stresses (e.g., desiccation [drying out], etc.) and may be transported by insects or wind over a wide geographical range. Bioaerosol Viability and Infectivity Once released, bioaerosols may travel considerable distances due to atmospheric dispersion. The ability of bioaerosols to cause adverse health effects or to initiate disease depends upon their ability to survive and remain infectious in the environment, as well as their exposure to a susceptible host. The survival or viability of bioaerosols is referred to as their ability to replicate, whereas the infectivity of bioaerosols is referred to as their ability to cause infection. Factors that influence bioaerosol viability and infectivity include: 2 AIR QUALITY EDUCATION IN ANIMAL AGRICULTURE Measuring: Bioaerosols Relative Humidity and Temperature Many bioaerosols are hygroscopic (can readily take up and retain water from the environment). After their generation, the viability of bioaerosols are impacted by the Bioaerosols can be rate of water transfer (dehydration or rehydration), which is dependent upon relative humidity (RH) and temperature in their environment. Most bioaerosols tend to lose made up of many 3 viability due to desiccation (drying out). different types of Oxygen Oxygen can be toxic for some species of microorganisms. Anaerobic airborne particles, including bacteria may lose viability due to oxygen toxicity, with their survival dependent upon storage time, oxygen concentration, and RH3. However, most bacterial species in bacteria, viruses, animal building aerosols are facultative anaerobes, which means that they thrive under parasites, fungi, low oxygen conditions but can survive and remain viable over long periods of time when exposed to ambient levels of oxygen in the environment. and other particles, Other Pollutants such as pollen, that It has been reported that pollutants such as sulfur oxides and nitrogen oxides have less effect on bioaerosols than ozone. Outdoor bioaerosol survival of many species may lead to adverse is much poorer than those indoors due to the presence of ozone in outdoor environ- ments. Because of this, the spread of airborne diseases is more likely indoors than health effects in an outdoors3. exposed population. Radiation Energetic radiation (e.g., UV) induces free-radical mediated reactions causing dam- age of nucleic acid, protein, sugar, lipid, and membranes within microbes. Long wave radiation (e.g., microwave) has much lower energy, and is considered to have limited impact on bioaerosol viability3. Bioaerosols in Animal Environments In intensive livestock production systems, bioaerosols are often rich in both variety and number3. The major sources of bioaerosols are animals, animal wastes, feed, and bedding materials. The nature and concentration of bioaerosols in animal environments may be essential in the etiology of animal diseases. It has been reported that patho- gens of livestock transmitted through the air may cause infectious diseases in farm animals, as well as in human farm workers and residents living in close proximity to farms. Table 2 lists some of the diseases that have been linked with airborne patho- gens in animal houses. The common pathogenic bioaerosols identified in poultry and pig houses are listed in Table 3. Table 2. Common infectious disease of farm animals and pathogens3 Host Diseases Factors implicated in causation pathogens environment Atrophic rhinitis Bordetella bronchiseptica Crowding pigs Pasteurella multocida Poor ventilation Enzootic pneumonia Mycoplasma suipneumoniae Poor drainage, high relative humidity Diarrhea Pneumonia Rotavirus, E. Coli, etc. Weaning, hygiene, cold Mycoplasma bovis, dispar Crowding, poor feeding cattle Shipping fever P. haemolytica, etc. High relative humidity, stress Environmental E. Coli, strep. uberis Contaminated bedding, stage of lactation mastitis horses Obstructive Mycropolyspora faeni Dusty feed and bedding, poor ventilation pulmonary disease Aspergillus fumigatus Measuring: Bioaerosols Measuring: Bioaerosols AIR QUALITY EDUCATION IN ANIMAL AGRICULTURE 3 Table 3. Common pathogenic bioaerosols