In the United States, animal production industry produces almost $100 billion per year in farm revenue. While contributing to the vitality of rural communities and insuring the sustainability of America’s food supply, intensive production of poultry and livestock has raised serious environmental concerns with the public. In fact, industrialized animal feeding operations (AFOs) are often perceived to be significant emitters of air pollutants that may pose threats to the health and welfare of surrounding communities. Future compliance with increasingly stringent local, state, and federal air pollution regulations is likely to occur. Sustainability and growth of the AFO industry to meet increasing demand for affordable meat, milk, poultry, and eggs will likely depend upon addressing health and environmental concerns. Science-based air emission data, effective and affordable solutions to emission mitigation are urgently needed.
The “air quality engineering & science” research team in BAE at NC State has been working on various aspects of air emissions problems associated with AFOs, specifically poultry operations. Research topics and interests include, but not limit to the following:

• Monitoring emissions of air pollutants from commercial scale AFO facilities. Baseline emissions of particulate matter (TSP, PM10 and PM2.5), ammonia, hydrogen sulfide, carbon dioxide, and volatile organic compounds (VOCs) from high-rise egg production systems have been established through the National Air Emission Monitoring Study, overseen by the US EPA.
• Characterizing the spatial and temporal variations in the physical, chemical, and biological properties of aerosols emitted from AFO facilities, leading to improved understanding of the mechanisms of generation, fate and transport of those aerosols.
• Developing interactive simulation models to predict the fate and transport of aerosol and bioaerosols (airborne microorganisms) emitted from AFO facilities.
• Modeling generation and volatilization of ammonia from broiler litter, leading to establishment of mechanistic emission models for estimation of ammonia emission fluxes from broiler litter under different growing conditions.
• Development and evaluation of various technologies for mitigating air emissions form AFO facilities.

Measurement and Modeling Plume-Rise of Air Emissions from Animal Housing Systems
Project funding agency: NSF CAREER Award No. CBET-0954673

Emissions of air pollutants from animal housing systems are of increasing interest due to the magnitude of the emissions and their adverse health effect to local communities. Many models have been developed to simulate dispersions of air emissions under certain conditions. Among these models, Gaussian dispersion models have been commonly used to evaluate fate and transport of PM emitted from animal housing and to link animal house PM emissions and local public exposure. Most of these models, however, focus on the emissions and dispersions of the air from industrial stacks. In application of these models, e.g. Gaussian dispersion models, for downwind concentration predictions of animal housing emissions, unknown plume rise (Dh) and plume shape (s_y and s_z) have been vital weak points challenging the accuracy of the model predictions.

The plume rise of animal housing emission is a function of existing velocity, temperature, humidity of ventilated air, etc. In this project, plume rises of different ventilation emissions will be directly measured using marked poles and open path techniques. Air velocities and the temperatures at different heights in the plume will be simultaneously monitored in the field using 3D sonic anemometers at different heights. Information of flow field velocities, temperatures, and meteorological conditions will be used to conduct CFD modeling and to develop mathematical models of plume rise under stable, unstable, and neutral atmospheric conditions.

Publications of the project: [Journal articles] & [conference papers]

Measurement and Modeling Bioaerosol Fate and Transport in the Vicinity of a Commercial Egg Production Farm
Project funding agency: NSF CAREER Award No. CBET-0954673
 

Air emissions from AFO facilities often contain high concentrations of microorganisms and other biologically active substances. While the technique of air dispersion modeling has been used to forecast plant disease transport for preventively reducing the risk of infection, there is limited information in the literature about AFO aerial emissions of airborne microorganisms (bioaerosols), and the atmospheric dispersion/fate and transport of these bioaerosols. It has been reported that viable bacteria in particles were detected up to 300 m downwind from AFO facilities. It is clear that the downwind viability and the survival of airborne pathogens affect disease isolation. It is not clear, however, the extent to which airborne microbial contaminations transport off the farm sites, and how this contamination might affect human health or other AFO facilities in the region.

This project investigates spatial and temporal variations of airborne microorganisms in the vicinity of AFO facilities with the goal of determining sources, fate and transport of pathogenic organisms associated with animal housing facilities. The study also aims to determine the size fractions of particles to which microbial indicator and pathogenic organisms attach.

Publications of the project: [Journal articles] & [conference papers]

Characterizations of Particulate Matter Emitted from Egg Production Facilities: Sources versus Public Exposure
Project funding agencies: USDA-NRI Grant No. 2008-35112-18757 & NSF CAREER Award No. CBET-0954673
 

This is a comprehensive study through which characterization of PM at a commercial egg production facility and its surrounding area have been examined. The ultimate goal of this ongoing project is to establish basic understanding of the relationships between mass and characteristics of PM emitted from AFO buildings and possible public exposure surrounding those facilities. This understanding will provide a basis for further study of health effects and risk assessment associated with AFO PM. Characteristics of PM in the egg production buildings and at representative upwind and downwind distances from the buildings (see the figure above) have been thoroughly investigated. The project focuses on accomplishing the following supporting objectives:

1. Characterization of PM at source and at the surrounding ambient locations:
   •  Mass concentrations (TSP, PM10, PM2.5)
   •  Physical properties: particle size distribution (PSD), particle shape, density
   •  Chemical speciation: OC, EC, ions, elements
   •  Biological properties: bacteria species, fungi
2. Fate and transport of PM – possible public exposure

The predicted outcomes of the project include:

1. Respond of PM characteristics to gas emissions (e.g. NH3), operational and environmental conditions
2.  Response of PM concentration & PSD to animal activity
3.  Predictive model for PM fate and transport
4.  Linkage of AFO PM emissions and public exposure
5. PM chemical compounds and biological characteristics–“fingerprints” as source identification for AFO PM

Publications of the project: [Journal articles] & [conference papers]

Design and Fabrication of a Poultry Production Simulation Chamber Complex for Air Quality and Animal Welfare Studies
Project funding agency: USDA –CSREES Grant No. SRGP-002216
 

The foundation for addressing air quality issues in animal agriculture lies in sound research, demonstration and evaluation of abatement solutions, and technology transfer. Currently, the scientific study of production broilers and their environments are conducted in production houses. In these settings, investigators have little or no control over the environment. This project is to design, fabricate and test a 9 environmentally controlled chamber complex that can, on demand, accurately simulate conditions typical of those observed in commercial broiler production environments. The 8ft x 8ft x 8ft stainless steel clad chamber unit design is modular, light-weight, re-configurable, well-insulated and easy to sterilize. Units can be ganged together into short tunnels or used singly. The modular wall panels allow for repositioning of ventilation ducts to create different flow regimes. The individual chamber system has separate ventilation and control system. This assists in data collection and validation as the same environment can be produced in multiple, isolated chambers.  Broilers progress through the production cycle with limited human exposure as a result of strategically places access panels. Once populated these chambers allow controlled air quality and animal welfare investigations within production environments and eventually lead to cost saving practices for producers. The chamber complex will also provide educational opportunities for students to acquire fundamental knowledge for developing careers in environmental air quality and animal well-being.

Publications of the project: [Posters 1, 2] [Presentations 2009, 2012] [Reports 2009, 2010, 2011]