Management Strategies to Reduce Air Emissions: Emphasis Dust and Ammonia

Transcription

1 2005 Poultry Science Association, Inc. Management Strategies to Reduce Air Emissions: Emphasis Dust and Ammonia P. H. Patterson*,1 and Adrizal *Department of Poultry Science, The Pennsylvania State University, University Park, Pennsylvania 16802; and Department of Feed and Animal Nutrition, Faculty of Animal Husbandry, University of Jambi, Jambi, Indonesia Primary Audience: Production Managers, Nutrient Management Specialists, and Environmental Engineers SUMMARY Air emissions generated by poultry production are numerous and can include dust, odors, endotoxins, microorganisms, and numerous gases. Ammonia (NH 3 ) emissions have the potential to contaminate surface waters and are an environmental concern on both a local and global scale. These emissions in and around poultry production facilities can be a health and performance issue for birds and their caretakers. Dietary strategies can aid in the reduction of many airborne emissions, including dust and ammonia. Management techniques to quell, capture, or eliminate these air contaminants are numerous but vary in their cost, effectiveness, and practicality. Endotoxins, microorganisms, and nitrogenous compounds also can adhere to dust particles. Techniques for dust control include simple house cleaning, oil and water fogging, windbreaks, different filters, precipitation, certain housing systems and equipment, and vegetative shelterbelts. Many of the same strategies to reduce dust will also reduce ammonia losses as well. Simple procedures, including good manure management, reducing stress and maintaining bird health, reduce nitrogenous losses. Litter and manure amendments aid in reducing ammonia volatilization, and like those techniques for dust control, poultry housing systems, biofilters, water filters, composting, and vegetative shelterbelts also have potential for ammonia mitigation. Key words: air emission, dust, particulate matter, ammonia, management strategy 2005 J. Appl. Poult. Res. 14: DESCRIPTION OF PROBLEM Air emissions from poultry and livestock production are numerous and may include dust or particulate matter, odors, endotoxins, methane, H 2 S, CO 2, H 2 O, and nitrogenous compounds, including ammonia [1, 2, 3]. Ammonia emissions can be significant. Our own data gathered using mass balance techniques with commercial laying hens, pullets, broilers, and tur- keys (Table 1) indicates that between 18 to 40% of feed N is lost to the atmosphere mostly as ammonia N [4, 5, 6, 7]. Ammonia emissions have the potential for wet and dry deposition and contamination of surface and ground waters [8, 9, 10]. The US Environmental Protection Agency estimates that 64 to 71% of ammonia emissions are from livestock and poultry production [11]. In the Chesapeake Bay airshed, current estimates indicate that poultry and livestock con- 1 To whom correspondence should be addressed: php1@psu.edu.

2 PATTERSON AND ADRIZAL: AIR EMISSIONS AND POULTRY PRODUCTION 639 TABLE 1. Partitioning (%) of feed nitrogen in commercial poultry 1 Manure Poultry Feed N or litter N Carcass N Egg N Atmospheric N Laying hens Pullets Turkeys Broilers Source: [4, 5, 6, 7]. tribute as much as 81% of the annual NH x atmospheric burden [12]. Nitrogen and sulfur oxide compounds (NO x SO x ) can be converted to nitric and sulfuric acid and are factors in acid rain formation [12]. Ammonia is, however, practically the only base in the gas phase of the atmosphere and reacts rapidly with available acids mainly sulfuric, nitric, and sometimes hydrochloric, forming their corresponding salts [13]. If ammonia molecular concentration is less than twice the sulfuric acid level, all available ammonia is transferred to the particulate phase to neutralize sulfuric acid clouds and droplets forming ammonium bisulfate. If ammonia concentration is greater than twice the sulfuric acid level, the excess is available to react with other acid vapors [13]. Nitrate and sulfate compete for available ammonia-forming particulate aerosols that, depending on their concentration, can influence inorganic particulate matter levels in the atmosphere [14]. The NRC National Academy of Science ad hoc committee on air emissions from animal feeding operations [15] recently summarized their concerns listing key air pollutants and their relative importance with respect to air quality in different geospatial scales (Table 2). The primary air pollutant of concern on a global, national, and regional scale is ammonia because of atmospheric deposition and haze. On a local scale, ammonia generated by animal feeding operations is a minor concern because it is rarely perceived at the low concentrations encountered outside confinement poultry housing as a result of dilution and dispersion after exhausting from the building. However, a major concern at the local level is odor because of its implications for quality of life for people in the immediate area. A significant concern is also placed on H 2 S at the local level for health and haze considerations as it is often a component of odor and particulate matter. Particulate matter (PM) 2.5 and PM10 are airborne particulate matter or dust less than 2.5 and 10 µm in size. They can result from combustion processes, but secondarily when ammonia, SO x and NO x react in the atmosphere to form ammonium sulfate and nitrate, they can contribute as much as half of the PM2.5. Although odor and H 2 S can be significant concerns at the local level, they may not be a dominant concern with poultry compared with other livestock species, as they do not have the impact on human health and haze as do dust and PM. In June 2004, the US Environmental Protection Agency sent letters to state authorities with additional counties showing nonattainment of the PM2.5 air quality standard (Figure 1). These were the basis of their final designations in November 2004 [16]. The negative impacts of air contaminants on poultry health and performance have been well documented. Dust with airborne microorganisms, including bacteria, viruses, fungi, and molds are concerns for respiratory disease. Endotoxins in litter are from the lipopolysaccharide membrane fragments of gram-negative bacteria. These inflammatory substances are capable of soliciting neutrophil recruitment, macrophage and complement activation, and histamine release [17]. Ammonia at various concentrations has been reported to result in keratoconjunctivitis [18], greater circulating white blood cells, and lymphocytic infiltration of the eye [19], increased susceptibility to airsacculitis [20] and Newcastle disease [21], poor growth and feed conversion [22, 23], and reduced egg production [24]. A recent report by Wathes et al. [25] suggests ammonia can have implications for animal welfare with potential damage to olfactory cells, affecting the birds sensation of taste, their feeding behavior, and performance. However, other researchers have noted little or no impact of

3 640 JAPR: Symposium TABLE 2. Potential importance of air emissions from animal feeding operations 1 Area and scale of concern Global, national Local property line Emission type and regional or nearest dwelling Primary effects NH 3 Major Minor Atmospheric deposition, haze N 2 O Significant Insignificant Global climate change NO x Significant Minor Haze, atmospheric deposition, smog CH 4 Significant Insignificant Global climate change VOC 2 Insignificant Minor Quality of human life H 2 S Insignificant Significant Quality of human life Particulate matter (PM), PM10 Insignificant Significant Haze PM2.5 Insignificant Significant Health, haze Odor Insignificant Major Quality of human life 1 Source: [15]. 2 Volatile organic compounds. environmental ammonia at 30 and 90 ppm on hen performance and egg quality [19] or on broiler production [26], with the exception of an increased feed:gain ratio at 60 vs. 0 ppm. The health impacts of this same group of airborne contaminants on people working in poultry and livestock confinement settings have also been well documented [18, 27, 28, 29, 30]. Symptoms include coughing, phlegm, eye irritation, dyspnea, congestion and discharge, chest tightness, wheezing, sneezing, and headache resulting in fatigue, behavior changes, lost days at work, and increased health and insurance costs. Reduced pulmonary function in poultry workers, including forced vital capacity, forced expiratory volume, and forced expiratory flow, are primarily from obstructive disorders [29, 30]. Chronic exposure to poultry and livestock airborne contaminants can result in hypersensitive lung disease, bronchial constriction, bronchitis, asthma, and other immunological changes, resulting in damage to epithelial and endothelial cells [30]. Donham et al. [29] concluded that the combined negative health effects of dust and ammonia in poultry housing are greater than their independent additive effects. They also concluded that the Occupational Safety and Health Administration exposure limits for dust (15 mg/m 3 ) and ammonia (50 ppm) are too high, recommending lower exposure limits for these combined substances at levels of 2.5 mg/m 3 and 7 ppm, respectively [29]. There are numerous dietary strategies for poultry aimed at reducing the generation and emission of ammonia in the production setting [31, 32, 33, 34, 35, 36]. For dust and particulates, experience has indicated that adding dietary fat can reduce feed dust for the animals and their caretakers [37, 38, 39, 40]. Although dietary strategies are important first lines of action that can significantly reduce air emissions, they are not the focus of this review. Management techniques aimed at reducing or capturing air contaminants generated in poultry production are numerous but vary in cost, effectiveness, and practicality. For the reasons stated above, we will be addressing management strategies aimed at reducing air emissions with an emphasis on dust and ammonia in this article. MANAGEMENT STRATEGIES FOR REDUCING DUST Reducing airborne contaminants and their release requires several approaches to reduce generation and emission and, finally, to enhance their dispersion. Effective control usually relies on more than 1 strategy beginning in the poultry house, then manure storage, and on to land application. Best management practices begin with reducing generation and emission. However, on a local scale enhancing dispersion can be an effective means of reducing the impact of PM2.5, PM10, H 2 S, and other odors upon neighbors and others negatively affected by their close proximity. Utilizing site planning, weather dispersion, and setback distances are effective means of allowing natural dilution of odor, dust, and gases. These same principles can be applied to ammonia and other airborne contaminants, although their negative impacts are primarily on

4 PATTERSON AND ADRIZAL: AIR EMISSIONS AND POULTRY PRODUCTION 641 FIGURE 1. The US Environmental Protection Agency nonattainment counties for PM2.5 air quality standards (June 2004) [16]. a regional, national, or global scale, requiring preemptive strategies focusing on reducing their generation and emission. House Cleaning A simple technique to reduce dust emissions from poultry buildings is regular house cleaning, including vacuuming and power washing between flocks, thereby reducing the volume and potential for contamination of the air in the house as well as air exhausted from the building [28, 37, 38]. Other potential benefits include reducing the potential of disease transmission, improved weight gain, feed conversion, and a reduction of the number of birds condemned at slaughter [41]. The main steps for house cleaning are remove equipment, remove litter or manure, dry clean, wet wash, disinfect, and thoroughly clean and disinfect the feeding and drinker systems and then allow enough downtime for the building to dry and to make house and equipment repairs and bait for rodents and other pests [42]. With dust and other airborne contaminants a greater issue than ever before, perhaps a new paradigm in house cleaning will be necessary with greater frequency for all bird types and cycles of production. Regular sweeping and vacuuming of poultry houses in locations where dust, feathers, and dander collect would likely improve air quality for birds and farm workers as well. Oil and Water Application Sprinkling oil in swine barns has been successfully used to reduce dust (23 to 80%) and other gases, including ammonia by 30% [43, 44]. Oil can be applied both manually with a handheld sprayer or automatically using a per-

5 642 manently installed sprinkler system [45]. It is important that droplet size is not too large, resulting in poor oil distribution, or too small, which may be a health hazard. According to Takai and Pederson [46], droplet size should be greater than 150 µm to obtain effective liquid application. In housing for laying hens, an ultrasonic sprayer generating 7- to 150-µm diameter particles with a 2% solution of emulsified canola oil significantly reduced dust with a diameter of 0.5 to 2 µm and 10 to 30 µm by 42 and 49%, respectively [47]. The authors went on to measure the dust that settled in petri dishes and found significantly greater amounts in the sprayed house compared with the control. Very high levels of dust at diameters of 0.3 to 5.0 µm were also measured in control and ultrasonic-sprayed housing for floor-reared broilers ( and particles/m 3, respectively). Although the ultrasonic-sprayed house levels represent a significant 47% reduction in dust concentration, the authors cautioned they were still 100 times that measured in the layer house [47]. Wachenfelt [48] compared dust levels in aviary systems for hens in reference periods before and during treatment spraying periods with pure water or oil and water mixtures with 10% oil. The oil and water mixtures reduced dust concentrations approximately 50%, whereas the pure water applications reduced dust to about one-third that of the reference periods. Ellen et al. [49] measured the impact of modifying relative humidity on dust levels in broiler houses. In houses fitted with fogging equipment, inhalable dust levels were reduced 13 and 22.5% during fall and spring flocks, when the buildings were maintained at 75% RH, compared with control buildings [49]. However, no differences were observed for respirable dust between the buildings. Windbreaks One simple strategy of enhancing the dispersion of dust and odor on a local scale are the use of natural and artificial windbreaks [37, 50, 51]. They reduce dust and odor downwind by both dropping particulates and lifting emissions into the upper air stream for greater dispersion and dilution. Natural windbreaks comprised of trees and shrubs take 3 to 10 yr to grow, offer visual protection for the farm, and also trap particulates and odor [50]. Artificial windbreak JAPR: Symposium walls are erected downwind from exhaust fans to reduce dust and odor emissions onto neighboring property [37]. Windbreak walls may not be suited for poultry buildings equipped with multiple fans at nonuniform locations around the building and are better suited for houses with concentrated fans, such as tunnel-ventilated houses. They can be built with various materials covering a wood or steel frame, such as plywood, tarps, or straw framed with wood and held in place with chicken wire. When walls are placed 3.0 to 6.1 m downwind of the fans, they work by reducing the forward momentum of the exhausted air allowing dust and odor to settle out at low air speeds near the building. At higher air speeds, the wall provides a sudden vertical lift for dispersion of exhausted air to mix with fresh outside air [50]. Biomass Filters Biomass filters are a cross between a windbreak wall and biofilter that will be addressed later in the section on Management Strategies for Reducing Ammonia. They are simply vertical barriers in close proximity to building exhaust fans made from inexpensive materials, such as chopped cornstalks, corncobs, loose straw, or other materials. Biomass filters use the principle that if dust is removed from the ventilation exhaust, a large amount of odor will be trapped with the dust. Researchers have tested the filters in swine buildings under cold weather ventilation conditions with significantly reduced dust (52 to 83%) and odor levels (43 to 90%) [37]. However, the performance of the biomass filters under high ventilation rates or with poultry species is not known. Nevertheless, their successful application in reducing dust and odor in swine barns [52] may also be applicable in poultry houses. Water Filters Particulate emissions from poultry houses can be trapped in filters utilizing water as a scrubbing media. These systems have been used in industrial air pollution control and have the potential to scrub dust, ammonia, sulfur compounds, and nitrous oxides from poultry houses. In a tunnel-ventilated swine building, fitted with evaporative cooling pads across the entire end

6 PATTERSON AND ADRIZAL: AIR EMISSIONS AND POULTRY PRODUCTION 643 of the building 1.2 m upwind from the exhaust fans, researchers measured a 20 and 60% reduction in total dust and a 33 and 50% reduction in ammonia levels at high and low ventilation rates, respectively [53]. Other systems have used 2 filter banks made from cellulose elements with water flowing from top to bottom through the first element and acidified water through the second [54]. Preliminary observations reduced dust (PM10) ammonia and odor from 70 to 80% in the exhaust air from a piggery. Reports on these systems in poultry houses are lacking, but their application and impact in poultry houses could be considerable, since the water filters aid in minimizing not only dust and odor but also ammonia, the gas of most concern in poultry operations. Electrostatic Precipitation Electrostatic charging of air in confined spaces has been used to reduce dust levels in both swine and poultry facilities [38, 55, 56]. These devices impart a negative charge to airborne particles, resulting in their precipitation on grounded surfaces. Application of an electrostatic space charge system in a broiler breeder house resulted in a 60% reduction in airborne dust; total bacteria were reduced 76% and ammonia by 56% [57]. Egg samples collected from this study showed less Salmonella contamination as well [57]. Other research with hatching cabinets and caged layers utilizing electrostatic charging have reduced dust from 82.8 to 98.7% and 36.6 to 65.6%, respectively, with particle sizes ranging from 0.3 to 25 µm [38, 58]. These authors have also demonstrated reduced airborne levels of Salmonella enteritidis in rooms with experimentally infected hens [59]. Although technically feasible, the authors cautioned that the economic merits of electrostatic charging in commercial poultry houses still needs to be determined. Poultry Housing Systems and Equipment Takai et al. [2] measured airborne dust concentrations and emission rates in poultry and livestock buildings and in England, Denmark, Germany, and The Netherlands and determined that cage systems for layers had significantly less inhalable and respirable dust than did perch- TABLE 3. Inhalable and respirable dust emission rates (mg/h 500 kg) from poultry buildings 1 Bird and Inhalable Respirable housing type dust dust Layer, cage Layer, perch 1,771 4, Broilers, floor litter 1,856 6, Range of values from England, Denmark, Germany, and The Netherlands [2]. style systems. Also, floor-reared broiler houses had more inhalable dust than either layer system (Table 3). Respirable dust is composed of small particles (<10 µm) that may be pulled deep into the alveoli, whereas nonrespirable or inhalable dust particles (>10 to 50 µm), which enter the nose and throat during normal breathing, may be found in upper airways [27, 60]. The authors went on to report that both inhalable and respirable dust concentrations were higher in winter than summer because of greater seasonal ventilation rates in summer. Inhalable and respirable dust concentrations were greater in poultry housing compared with either pig or cattle buildings [2]. Wathes et al. [1] reported similar differences between poultry housing systems, documenting greater dust levels among floor-reared broilers compared with perch or cage layer systems. In addition, endotoxin levels in both the inhalable and respirable fractions were greater in perch systems for layers compared with either layers in cages or floor-reared broilers [1]. These observations indicate there remain beneficial properties of cage layer systems in terms of air quality for both poultry welfare and farmer health compared with popular perch-type systems or traditional floor-reared broilers. Other nontraditional cage systems for broilers with manure belts that run intermittently (8 cm/s per 3 h) removing manure from the house demonstrated potential benefits, including better air conditions, low levels of breast blisters, and bacterial contamination of skin and feathers [61]. Vegetative Shelter Belts Strategically planting trees, shrubs, and other vegetation around poultry houses offers several potential benefits according to Malone and Van- Wicklen [50]. Trees can foster better neighbor

7 644 JAPR: Symposium FIGURE 2. Merits of using vegetative shelter belts around poultry houses [50]. relations by filtering dust, feathers, odor, and noises from the operation, providing a visual screen from routine activities, and enhancing the publics perception of the industry. Furthermore, there are possible production benefits as a windbreak and a source of shade to reduce seasonal temperature extremes and as a filter for airborne pathogens for improved biosecurity (Figure 2). Malone [62] reported a 3-row planting of bald cypress (4.9 m high), Leyland cypress (4.3 m), and red cedar (2.4 m) 9 m wide and 9 m from 2 tunnel fans on a commercial broiler farm reduced air speed from to 1.5 m/min from the front to the back of the trees. Total dust levels were reduced 53% (0.659 to mg/ m 3 ) and 50% (1.039 to mg/m 3 ) in years 2002 and 2003, respectively. MANAGEMENT STRATEGIES FOR REDUCING AMMONIA The metabolic end product of protein and nitrogen metabolism in the domestic fowl is uric acid. Typical excreta contains 13 to 17 g/kg total N on a DM basis, with 60 to 75% as uric acid N, 0 to 3% urea N, 0 to 3% ammonium N, and 25 to 34% as undigested protein N [63]. The breakdown of uric acid (C 5 H 4 O 3 N O 2 + 4H 2 O 5CO 2 + 4NH 3 ) and protein is mediated by microorganisms. The enzyme uricase is commonly present in microorganisms and specific to this reaction. The first step in the breakdown of uric acid is hydrolysis to allantoin (Figure 3). Most uric acid breakdown is aerobic, although a small fraction is anaerobic as well. Conditions that favor uric acid decomposition by bacteria include temperatures greater than 20 C, ph in the range of 5.5 to 9.0, and litter moisture and water activity of 40 to 60% and <0.625, respectively [63]. Although water activity (A w ), which is the amount of water available for microbes to start decomposition, is considerably important, water potential is more readily measured and indicative of the water interaction within the manure or litter [63]. These same conditions that favor the decomposition of uric acid favor the growth and proliferation of pathogenic microorganisms, such as Salmonella and Escherichia coli [64]. Therefore, a thorough understanding of these principles is paramount to implementing litter and other management strategies for reducing ammonia losses. Reduce Stress and Maintain Bird Health Bird health and status of the gastrointestinal tract are critical for proper nutrient retention. Temperature and humidity stressors are real challenges and can occur with improper brooding conditions or equipment and poor ventilation

8 PATTERSON AND ADRIZAL: AIR EMISSIONS AND POULTRY PRODUCTION 645 Manure and Litter Management Simple management procedures can greatly impact manure moisture and the loss of ammonia. Moisture contamination of litter can come from excessively wet feces, and dietary factors that control wet droppings are important factors. Drinker management, including maintenance for leaks and height adjustment, impacts litter moisture. Research has shown that litter dry matter content is higher and nitrogen losses are reduced with nipple drinkers compared with bell drinkers [31, 32]. Exogenous water contamination of litter must be controlled from rain, surface, and ground water sources. In the case of turkeys that may be on litter for 20 or more weeks, good litter management includes frequent rototilling to reduce litter moisture levels to 30% or less. Lastly, proper ventilation in all seasons will exhaust bird moisture on a daily basis, minimizing moisture accumulation in the litter. This principle of balancing ventilation rate with house temperature within the thermal neutral zone for poultry or pigs was demonstrated by Vranken et al. [65] to reduce potential yearly ammonia emissions 8 to 13%. In their study, higher ventilation rates induced a greater discharge of inside air and caused lower inside temperatures. However, for Belgian weather conditions, the effect of the lower temperature was greater than the effect of the higher ventilation rate and resulted in lower ammonia emissions. FIGURE 3. Aerobic breakdown of uric acid [63]. design, equipment, or practices. Exposure to viral, bacterial, and other agents can stress birds, resulting in watery droppings, diarrhea, and poor feed conversion. Healthy birds maintained in a thermoneutral environment are better able to use dietary nutrients to their fullest potential and minimize flushing of dietary and endogenous nitrogen and moisture. Lastly, bird density and crowding can magnify other stressors, leading to poorer nutrient use. Manure and Litter Amendments An important tool in modern broiler management is the use of litter amendments that can trap and hold litter nitrogen using one of several techniques, including adsorption, acidification, or salts to manipulate microbial populations and enzyme activities. Reece et al. [66], Terzich [67], and Moore et al. [68] demonstrated the ability of several compounds, including sodium bisulfate, ferric chloride, ferrous sulfate, phosphoric acid, superphosphate, and aluminum sulfate to reduce ammonia volatilization from the litter of floorreared broilers. Work by Kim and Patterson [69] demonstrated that ZnSO 4, CuSO 4, MgSO 4, and MnCl 2 can all reduce microbial uricase activity. Zinc sulfate was the most effective in reducing manure ph and the growth of uric acid utilizing bacteria. When added to fresh broiler manure, ZnSO 4 reduced ammonia volatilization and increased manure uric acid N and total N retention in the samples by almost 2-fold. Dietary supplementation of Zn can also reduce ammonia losses [70] and increase manure uric acid N and total N retention [71]. However, these and other litter amendments with trace elements, such as Cu and Zn, may have issues for plant toxicity and environmental contamination. Wilson [72] reported on the application of liquid alum in the pit of a commercial high-rise hen house, utilizing RainBird irrigation nozzles to spray 10 s every h. Ammonia levels at bird

9 646 height were reduced from 70 to 40 ppm within 20 min of the first application, and with additional time ammonia levels continued to fall in a stairstep fashion to approximately 20 ppm by 3 h. Organic acids are another choice to acidify litter and reduce ammonia volatilization. Ivanov [73] treated broiler litter with 5% citric acid, 4% tartaric acid, or 1.5% salicylic acid and reduced litter ph below 5, reduced both litter and air ammonia concentrations, and inhibited the growth of E. coli, Salmonella enteritidis, Proteus, and Pseudomonas spp. ( cfu g 1 of litter). The cost of the organic acid treatments ranged from $0.08 to $0.10 per bird with 15 birds/m 2 and a 2.5 feed conversion. Amendments with nitrifying bacteria have the potential to reduce manure NH 3 and NH 4 + levels as bacteria oxidize them to nitrite and nitrate, NO 2 and NO 3, respectively [37, 74]. Other novel strategies we may see in the future include immunizing birds against the enzymes responsible for ammonia formation. Pimentel and Cook [75] immunized broiler breeder and Leghorn hens with jackbean urease enzyme. The hens developed antibodies to the enzyme and passed them on as maternal antibodies to their chicks. The harmful effects of ammonia in the intestinal tract were reduced by preventing urea hydrolysis to ammonia by intestinal bacteria. Kim and Patterson [76] showed that it was possible to immunize hens with microbial uricase and produce high levels of uricase-specific antibodies in the egg yolk. This is the first enzymatic step in the natural hydrolysis of uric acid. These antibodies (IgY) have the potential as manure amendments or as a dietary supplements to reduce the breakdown of uric acid to urea. Composting Ammonia emissions during litter composting can be significant, increasing environmental pollution and reducing fertilizer value. However, composting at the right moisture, carbon:nitrogen ratio, and temperature with proper aeration can reduce ammonia losses and retain fertilizer value [77, 78, 79]. Among 4 types of carbon-rich amendments for aerobic composting of poultry manure, Mahimaraja et al. [79] found that wheat straw and peat reduced ammonia losses by 33.5 and 25.8%, respectively, compared with untreated control manure and were superior to JAPR: Symposium wood chips or paper waste as carbon amendments. The authors also compared adsorbent amendments and determined that zeolite was a more effective NH 3 (or NH 4 ) adsorbent than soil and reduced NH 3 losses by 60%. Extractable NH + 4 N was almost 1,000 times higher than NO 3 N in all compost mixtures, suggesting little oxidation of NH + 4 to NO 3 (nitrification). Total N levels in the compost at the end of the experiment showed a loss of about 50% during aerobic incubation but only 17% from NH 3 volatilization, indicating N loss through denitrification could be considerably higher than through NH 3 volatilization. Other investigators have shown that composting amendments, including zeolites, calcium and aluminum salts, and acidifiers have improved nitrogen retention and reduced ammonia volatilization compared with nonamended hen manure [80]. Properly done, composting can bring litter to a stable end point for overwinter storage and effectively reduce ammonia losses to the atmosphere. Poultry Housing Systems Wathes et al. [1] reported differences in environmental ammonia levels between poultry housing systems in the UK with greater average concentrations in floor-reared broiler houses compared with cage or perch systems for layers at 24.2, 13.5, and 12.3 ppm, respectively. Similarly ammonia emissions from housing systems for laying hens with litter were about 4 times higher than with battery cages [63]. Focusing on ammonia emissions related to building design in his review of literature, Groot Koerkamp [63] found that battery systems with manure belts underneath the cages would reduce the emission rate of ammonia to 34 g/hen per year compared with deep pit housing systems at 386 g/hen per year. The belted system was even more efficient at reducing ammonia losses if the manure was removed at least twice daily instead of twice weekly [63]. Novel housing systems for broilers in The Netherlands that used a trampoline floor with air circulation through the floor for rapid drying of droppings increased litter DM to almost 80% compared with 56% in conventional housing and reduced ammonia levels in half [81]. The efficiency of managing manure and emissions using a net-belted floor for broilers to eliminate the manure from the house was also

10 PATTERSON AND ADRIZAL: AIR EMISSIONS AND POULTRY PRODUCTION 647 demonstrated by Okumura and Hosoya [61]. These observations indicate there remain beneficial properties of belted-cage or perch systems for layers and novel nonlitter systems for broilers in terms of air quality for both poultry welfare and farmer health compared with traditional floor-rearing facilities. Biofilters Biofilters are a proven technology to filter dust, ammonia, hydrogen sulfide, and odors [37]. They rely on a biological filter material usually organic in nature with a resident microbial film that aids in the degradation of gases and odors in addition to its trapping function. The contaminants are then oxidized to produce biomass, CO 2, H 2 O, and inorganic salts. Straw, compost, and woodchips are good filter materials as long as particle size and porosity is maintained for good airflow without significant pressure drop and added amperage draw on the fans. Passing the exhaust air from a pig-finishing unit through a humidifier and biofilter consisting of a wood chip media (>20 mm) with a moisture content of >63% helped reduce odor and ammonia by 77 to 95% and 54 to 93%, respectively [82]. The pressure drop across the biofilter ranged from 14 to 64 Pa. The authors observed greater odor and ammonia concentrations when the moisture level in the filter medium dropped below 50%. Others have suggested best management practices for the systems include maintaining media moisture levels at approximately 50% [83] and implementing rodent control programs to prevent infestation. In swine facilities fitted with biofilters, Nicolai and Jani [84] measured a 53, 80, and 83% reduction in ammonia, hydrogen sulfide, and odor, respectively. Performance results under cold and mild weather ventilation have been acceptable; however, there were challenges under high airflow situations, resulting in elevated static pressure, as airflow is restricted through the media. Water Filters Emissions can be trapped in filters utilizing water as a scrubbing media. These systems have been used for control of industrial air pollution and have the potential to scrub dust, ammonia, sulfur compounds, and nitrous oxides from poultry houses. In a tunnel-ventilated swine building, fitted with evaporative cooling pads across the entire end of the building 1.2 m upwind from the exhaust fans, researchers measured a 33 and 50% reduction in ammonia levels and a 20 and 60% reduction in total dust at high and low ventilation rates, respectively [53]. Another system reported in the literature used 2 filter banks made from cellulose elements with water flowing from top to bottom through the first element and acidified water through the second [54]. Results indicated ammonia, odor, and dust (PM10) were reduced from 70 to 80% in exhaust air of a swine building. While we are not aware of any poultry examples using water filters, they may have application once their economic and technical practicality is demonstrated. Ozonation Ozone (O 3 ) is a powerful oxidizing agent and a natural germicide. Ozone in the upper atmosphere protects the earth from harmful solar radiation; however, it is also a toxic gas at high levels here on the surface. Researchers have demonstrated its ability to react with other gases reducing odor intensity, ammonia (15 to 58%), and dust (58%) in swine facilities [37]. Although not used in commercial practice, future ozone evaluations and applications with poultry would be useful. Vegetative Shelter Belts As previously stated, trees, shrubs, and other vegetative materials strategically planted around poultry houses have the potential to foster better neighbor relations by filtering dust, feathers, odor, and noises [50]. Potential environmental benefits include reduced atmospheric ammonia losses and surface and groundwater contamination. A demonstration site on the Delmarva Peninsula has shown a 67% reduction in ammonia levels downwind of the vegetative filter belt planted on commercial broiler farms [62]. The ability of plant materials to filter, adsorb, or incorporate airborne ammonia remains to be documented on commercial poultry farms, although there are other data sets of literature that suggest plants differ in their sensitivity and ability to use atmospheric ammonia [85, 86, 87, 88, 89, 90]. Work with vegetative filter belts for

11 648 poultry farms is ongoing in Delaware, Iowa, and Pennsylvania with a USDA research and outreach project. Furthermore, there are other possible production benefits for commercial JAPR: Symposium poultry as a windbreak and a source of shade to reduce seasonal temperature extremes and as a filter for airborne pathogens for improved biosecurity. CONCLUSIONS AND APPLICATIONS 1. The goals of all strategies aimed at reducing air emissions are ultimately the welfare and performance of the birds, the comfort and health of caretakers and neighbors, and the preservation of air and water quality on a local, regional, and global scale. 2. Reducing airborne contaminants requires several approaches to first reduce their generation, emission, and, in some instances, enhance their dispersion to reduce concentrations at bird and worker level. 3. Dust management begins with simple house cleaning, oil, water, and electrostatic precipitation, and various filter techniques, including vegetative shelter belts as a last measure to trap dust and particulates leaving the farm. 4. Management strategies for ammonia are equally numerous and include good bird and manure management, the use of litter amendments, poultry housing systems that impact manure moisture and ammonia emissions, biofilters, water filters, and vegetative shelter belts for adsorption and incorporation of nitrogenous compounds. 5. Although regulations concerning particulates, ammonia, and other gases are already in place, their application and interpretation for animal agriculture remains to be defined. Furthermore, only regulatory pressure will drive the application of dust and ammonia mitigation strategies and only then will the cost-to-benefit ratio of these techniques be realized. REFERENCES AND NOTES 1. Wathes, C. M., M. R. Holden, R. W. Sneath, R. P. White, and V. R. Phillips Concentrations and emissions rates of aerial ammonia, nitrous oxide, methane, carbon dioxide, dust, endotoxin in UK broiler and layer houses. Br. Poult. Sci. 38: Takai, H., S. Pedersen, J. O. Johnsen, J. H. M. Metz, P. W. G. Groot Koerkamp, G. H. Uenk, V. R. Phillips, M. R. Holden, R. W. Sneath, and J. L. Short Concentrations and emissions of airborne dust in livestock buildings in Northern Europe. J. Agric. Eng. Res. 70: Seedorf, J., and J. Hartung Emission of airborne particulates from animal production. Pages 1 16 in 2000 Livestock Farming and the Environ. Workshop Series of Conf. Section of Sustainable Anim. Prod. Accessed Dec Patterson, P. H., and E. S. Lorenz Manure nutrient production from commercial White Leghorn hens. J. Appl. Poult. Res. 5: Patterson, P. H., and E. S. Lorenz Nutrients in manure from commercial White Leghorn pullets. J. Appl. Poult. Res. 6: Patterson, P. H., E. S. Lorenz, and W. D. Weaver, Jr Litter production and nutrients from commercial broiler chickens. J. Appl. Poult. Res. 7: Patterson, P. H., R. M. Hulet, and E. S. Lorenz The Pennsylvania State University, State College, PA. Unpublished data. 8. Paerl, H. W Coastal eutrophication in relation to atmospheric nitrogen deposition: Current perspectives. Ophelia 41: Paerl, H. W Connecting atmospheric nitrogen deposition to coastal eutrophication. Environ. Sci. Technol. 36:323A 326A. 10. Paerl, H. W., R. L. Dennis, and D. R. Whitall Atmospheric deposition of nitrogen: Implication for nutrient over-enrichment of coastal waters. Estuaries 25: US EPA The National Air Pollutant Emission Trends: EPA-454/R (March 2000). chief/trends/trends98/. Accessed Dec Seifert, R. L., J. R. Scudlark, A. G. Potter, K. A. Simonsen, and K. B. Savidge Characterization of atmospheric ammonia emissions from commercial chicken house on the Delmarva Peninsula. Environ. Sci. Technol. 38: Pandis, S. N Ammonia and atmospheric chemistry. Sixth Discover Conference on Food Animal Agriculture: Nitrogen losses to the atmosphere from livestock and poultry operations th.htm. Accessed July Ansari, A. S., J. J. West, and S. N. Pandis Marginal PM2.5-nonlinear response to sulfate reductions. J. Aerosol Sci. 29:S195 S National Research Council Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs. Natl. Acad. Press, Washington, DC. 16. US Environmental Protection Agency EPA response to state recommendations of PM2.5 designations June 29, Accessed July Reynolds, S. J., P. S. Thorne, K. J. Donham, E. A. Croteau, K. M. Kelly, D. Lewis, M. Whitmer, D. J. J. Heederik, J. Douwes,

12 PATTERSON AND ADRIZAL: AIR EMISSIONS AND POULTRY PRODUCTION 649 I. Connaughton, S. Koch, P. Malmberg, B. M. Larsson, and D. K. Milton Comparison of endotoxin assays using agricultural dusts. Am. Ind. Hyg. Assoc. J. 63: Bullis, K. L., G. H. Snoeyenbos, and H. Van Roekel A Keratoconjunctivitis in chickens. Poult. Sci. 29: Patterson, P. H., E. S. Lorenz, G. L. Hendricks, M. A. Kalameh, D. Weinstock, and M. M. Mashaly The effect of environmental ammonia on egg production, egg quality, and immunity of commercial laying hens. CD Paper P15.22 in Proc. XXII World s Poult. Congr., Montreal, Canada. 20. Kling, H. F., and C. L. Quarles Effect of atmospheric ammonia and the stress of infectious bronchitis vaccination on Leghorn males. Poult. Sci. 53: Anderson, D. P., C. W. Beard, and R. P. Hanson The adverse effects of ammonia on chickens including resistance to infection with Newcastle disease virus. Avian Dis. 8: Reece, F. N., B. D. Lott, and J. W. 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Coufal, P. L. Niemeyer, J. B. Carey, R. E. Lacy, R. K. Miller, and R. C. Beiyer Impact of dietary supplemental methionine sources on sensory measurement of odorrelated compounds in broiler excreta. Poult. Sci. 83: Liang, Y., H. Xin, E. F. Wheeler, R. S. Gates, H. Li, J. S. Zajaczkowski, P. Topper, K. D. Casey, B. R. Behrends, D. J. Burnham, and F. J. Zajaczkowski Ammonia emissions from U.S. poultry houses: laying hens. Trans. ASAE. 37. Jacobson, L., J. Lorimor, J. Bicudo, and D. Schmidt Emission control strategies for building sources. Lesson 41 in Livestock and Poultry Environmental Stewardship Curriculum. MidWest Plan Service. Iowa State University, Ames, IA. 38. Mitchell, B. W., P. S. Holt, and K. H. Seo Reducing dust in a caged layer room: an electrostatic space charge system. J. Appl. Poult. Res. 9: Heber, A. J Effects of high-oil corn and soybean oil additives on dustiness of ground corn and feed. Trans. ASAE 45: Takai, H., and S. 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