Poultry-emitted air pollutants, including particulate matter (PM) and ammonia, have raised concerns due to potential negative effects on human health and the environment. However, developing and optimizing remediation technologies requires a better understanding of air pollutant concentrations, the emission plumes, and the relationships between the pollutants. Therefore, we conducted ten field experiments to characterize PM (total suspended particulate [TSP], particulate matter less than 10 μm in aerodynamic diameter [PM10], and particulate matter less than 2.5 μm in aerodynamic diameter [PM2.5]) and ammonia emission-concentration profiles from a typical commercial poultry house. The emission factors of the poultry house, which were calculated using the concentrations and fan speed, were 0.66 (0.29–0.99) g NH3-N bird−1d−1 for ammonia, 52 (44–168) g d−1AU−1 (AU = animal unit = 500 kg) for TSP, 3.48 (1.16–9.03) g d−1AU−1 for PM10, and 0.07 (0.00–0.36) g d−1AU−1 for PM2.5. PM and ammonia emission concentrations decreased as distance from the fan increased. Although emission concentrations were similar in the daytime and nighttime, diurnal and nocturnal plume shapes were different due to the increased stability of the atmosphere at night. Particle size distribution analysis revealed that, at a given height, the percentage of PM10 and PM2.5 was consistent throughout the plume, indicating that the larger particles were not settling out of the airstream faster than the smaller particles. Overall, the direction of the measured air pollutant emission plumes was dominated by the tunnel fan ventilation airflow rate and direction instead of the ambient wind speed and direction. This is important because currently-available air dispersion models use ambient or modeled wind speed and direction as input parameters. Thus, results will be useful in evaluating dispersion models for ground-level, horizontally-released, point sources and in developing effective pollutant remediation strategies for emissions.

Particulate matter (PM) released from the processes of livestock production has a negative impact on the health of animals and workers. Herein, the concentration, major chemical components, morphology and microbiological compositions of particulate matter 2.5 (PM2.5, particles with aerodynamic diameter less than 2.5 μm) in a broiler breeding house were investigated. The results showed that the PM2.5 distribution in the chicken house was affected by the illumination, draught fans, chicken frame structure and activity of the chickens in the broiler breeding house. Component analysis showed that organic carbon (OC) accounted for the largest proportion, and followed by element carbon (EC), SO42−, NO3−, NH4+, Na+, K+ and Ca2+. Ultrastructural observations revealed that the shape of PM2.5 had a round, rectangular, chain-like and irregular shape. The concentration of endotoxin was approximately 0.3 EU/m3. Microbiological analysis showed that at the genus level, the pathogenic bacteria included Staphylococcus, Corynebacterium, Enterococcus, Parabacteroides, Escherichia and Megamonas. The abundant harmful fungi were Aspergillus, Scopulariopsis, Wallemia, and Fusarium. Through redundancy analysis (RDA) analysis, we determined that OC, EC, Na+, K+, and NH4+ had strong correlations with Brachybacterium, Brevibacterium, Corynebacterium, Escherichia, Scopulariopsis and Microascus. SO42− was closely related to Scopulariopsis and Salinicoccus. Salinicoccus was also strongly correlated with NO3−. Our results indicated that feed, faeces, and outside soot are contributed to the increase in PM2.5 concentration in the chicken house, while the sources of the dominant bacterial and fungi might be feed, faeces, suspended outside soil and cereal crops.

Concentrated animal-feeding operations (CAFOs) are considered a source of airborne human pathogens and antibiotic resistance genes. Although bacterial abundance and diversity have been well studied, limited information on the size distribution of bioaerosols has prevented a clear understanding of the health effects of exposure to bioaerosols from CAFOs. Here, different sizes of particles were sampled from the inside and outside of atmospheric environments of layer and broiler feeding operations using 8-stage Andersen samplers. The quantitative real-time polymerase chain reaction (qPCR) and 16S rDNA-based sequencing were used to analyze the characteristics of biological abundance and diversity, respectively, according to size. The results indicated that size-related differences occurred in terms of airborne bacterial richness, diversity, and concentration at poultry-feeding operations. The richness of biological genera in the urban atmospheric environment was lower than in concentrated poultry-feeding operations. The biological diversity of airborne bacterial genera, including genera associated with potential pathogens, varied according to size. The bacterial lineages of bioaerosols present in the 7 size stages for layers clustered apart from those for broilers, suggesting that the type of poultry house is a more important factor than the particle size in shaping the microbial communities. In most cases, the concentrations of the 16S rDNA, Escherichia coli, tetW, and tetL genes increased as the particle size increased, with the geometric mean diameters varying from 4.7 to 5.8 μm. These results regarding the size-related differences in the diversity and abundance of bioaerosols will facilitate a better understanding of the potential health impact on both poultry and humans working in such environments.

The adverse effects of air emissions from animal feeding operations (AFOs) on public health, environment, and quality-of-life have been well-documented. Regulations or lawsuits may force AFOs to reduce their air emissions. Since livestock barn particulate matter (PM) has relatively high particle density and diameter and many gasses adsorb onto PM, its filtration might reduce air emissions. A porous windbreak wall that imposes acceptable backpressure (< 12.5 Pa) and covers the fan could be a promising option. Seventy-two different porous windbreak wall scenarios were modeled to compare their backpressure on the fan as well as average airspeed over the ground. These scenarios were combinations of shape (box, chamfered, curved), size (lengths of 2, 2.5, and 3 fan diameters), presence or absence of an opening (opened and closed), screen porosity (mosquito screen or clean screen, SunBlocker 70% or clogged screen), and fan angle and height. Backpressure and airspeed decreased with increasing windbreak wall length. Generally, the box-shaped windbreak wall had lower backpressure and airspeeds than the other shapes. The increased backpressure with clogged screen even at two fan diameters (2d) was acceptable. The tilted fan commonly used in poultry houses had higher backpressure and airspeed over the ground than the non-tilted fan used in swine houses due to the former’s lower surface area and tilt towards the ground. Overall, taking into account cost considerations and footprint size (for retrofittability), despite its higher airspeed over the ground (vs. larger footprints) and modest reduction in airflow rate, the 2d, open box model seems the most promising option.

Poultry houses emit large amounts of pollutants, e.g., ammonia and particulate matter (PM), that can affect public health, environment, and quality-of-life, due to odor. Poultry producers need low-cost and low-pressure treatments that can be compatible with existing ventilation systems. The porous windbreak wall coupled with a vegetative strip seems promising as it dissipates exhaust gases and traps PM (as well as adsorbed gases) on the screen, soil surface, as well as in the vegetation. Different windbreak wall-vegetative strip system designs were evaluated to treat the exhaust from 0.9-m fans in two types of layer house, for their abilities to reduce pollutant and odor emissions. The porous chamfered-shape windbreak wall with a footprint length of 3 fan diameters proved the most effective in reducing emissions. Even with a low system pressure of ~ 5 Pa, it greatly reduced odor, by 79% at 10 m and 59% at 5 m. It reduced TSP emissions moderately, by an average of 41%, while ammonia emissions were reduced slightly (by 21%). The chamfered screen was more readily cleaned by rainfall given the sticky nature of poultry house exhaust than the vertical screen. Overall, this low-cost, retrofittable, and modular system with a small footprint could be used by layer producers and, probably, by other poultry producers to reduce their emissions, alone or in combination with other mitigation methods to obtain greater reduction in emissions.

Limited data are available on ammonia (NH₃), nitrous oxide (N₂O), carbon dioxide (CO₂) and methane (CH₄) emissions from poultry housing in Mediterranean countries. The aim of the present study was to assess the NH₃, N₂O, CO₂ and CH₄ emission rates from commercial breeding hen and broiler houses under Mediterranean climate conditions. Research was conducted at one commercial breeding hen house and in two commercial broiler houses located in central Portugal. The environmental conditions, gas concentrations and ventilation rates were measured in the cold (8.0 ± 2.1 °C) and hot (20.7 ± 1.9 °C) season for the breeding hen house, whereas for the two broiler houses, measurements were made during one fattening cycle in the fall (17.3 ± 1.7 °C) season. Results showed that the annual average emission rates for breeding hen and broiler houses were 0.52 ± 0.27 and 0.06 ± 0.01 for NH₃, 0.030 ± 0.042 and 0.006 ± 0.001 for N₂O, 169.6 ± 56.2 and 58.0 ± 15.1 for CO₂ and 0.092 ± 0.131 and 0.0113 ± 0.0002 g day⁻¹ bird⁻¹ for CH₄, respectively. The N₂O emission rates observed in breeding hen houses may have been overestimated, being higher than previously reported for Mediterranean countries.

Mojave yucca (Yucca schidigera) is widely grown in the deserts. This herb is commercially used because it is rich in saponins and phenolic compounds with antioxidant effect. Y. schidigera or its derivatives are included as nontoxic food supplements, in cosmetics, and in the pharmaceutical industry. Saponins originated from Y. schidigera have anti-inflammatory, antioxidant, immunostimulatory, growth promoter, hypocholesterolemic, and hypoglycemic effects. To date, the key role of Y. schidigera or its products in animal nutrition is to reduce the ammonia content in the atmosphere and fecal odor in poultry excreta. Mitigating ammonia by using this plant could be achieved by the modification of gut microbiota, enhancement in digestion, and absorption of nutrients, leading to a better growth and production performance of animals and poultry. Various methods were applied to mitigate the emission of odor from the litter by different strategies including biofilters, litter treatments, air scrubbers, neutralizing agents, windbreak walls, etc., but these techniques are expensive. This article provides a new insight to scientists and poultry breeders to use Y. schidigera plant or its products as inexpensive and safe sources of a feed supplement to overcome the ammonia and fecal odor problems, as well as reduce environmental pollution in poultry houses.

Due to greater consumption of poultry products and an increase in exports, more poultry houses will be needed. Therefore, it is important to investigate ways that poultry facilities can coexist in close proximity to residential areas without odors and environmental challenges. Ammonia (NH₃) is the greatest concern for environmental pollution from poultry production. When birds consume protein, they produce uric acid, ultimately converted to NH₃ under favorable conditions. Factors that increase production include pH, temperature, moisture content, litter type, bird age, manure age, relative humidity, and ventilation rate (VR). NH₃ concentration and emissions in poultry houses depend on VR; seasons also have effects on NH₃ production. Modern ventilation systems can minimize NH₃ in enclosed production spaces quickly but increase its emissions to the environment. NH₃ adversely affects the ecosystem, environment, and health of birds and people. Less than 10 ppm is the ideal limit for exposure, but up to 25 ppm is also not harmful. NH₃ can be minimized by housing type, aerobic and anaerobic conditions, manure handling practices, litter amendment, and diet manipulation without affecting performance and production. Antibiotics can minimize NH₃, but consumers have concerns about health effects. Administration of probiotics seems to be a useful replacement for antibiotics. More studies have been conducted on broilers, necessitating the need to evaluate the effect of probiotics on NH₃ production in conjunction with laying hen performance and egg quality. This comprehensive review focuses on research from 1950 to 2018.

The high amount of particulate matter from poultry houses in the exhaust air, especially at different types of laying hen barns, is the main challenge farmers are faced with concerning emissions. As a possibility for the mitigation of particulate matter in the outgoing air, a dry filter based on the principle of centrifugal force was investigated under laboratory and field conditions. Aerosol spectrometers were used for continuous measurements in raw and clean gas. Field experiments took place under summer and winter conditions, so that filter efficiency under different climate conditions could be compared and measurement values at the barn were continuously collected over 24-h periods. Data collected under laboratory conditions showed a high efficiency of the dry filter, whereas results of the field experiments differed in each size fraction of the particulate matter. These differences may be explained by the fact that under laboratory conditions, better circumstances for correct measuring were created, e.g., laminar flow of the air.