Experts from six universities examine a large amount of data on the topic of air quality and focus information and conclusions around the key livestock areas of swine, poultry, dairy and beef in a recently released issue paper entitled, "Air Issues Associated with Animal Agriculture: A North American Perspective." The analyses contained in the paper look at a wide scope of issues ranging from greenhouse gas emissions to the logistics of manure storage facilities. The Council for Agricultural Science and Technology (CAST) created the issue paper in order to offer research-based information pertaining to an often-controversial topic.

The paper points out that federal, state and local regulation of livestock industry air emissions has been increasing steadily during the past 20 years. Livestock producers are using both mitigation technologies and management practices, while working to comply with a host of regulations. Diet manipulation is one example of an approach being used by many different species in an effort to comply with regulations. The paper summarizes the key air emissions challenges faced by each species group.

Swine production systems generate a large variety of air emissions, including ammonia, hydrogen sulfide, odor, volatile organic compounds (VOCs), particulate matter, bioaerosols and greenhouse gases, all in quantities of concern, according to the paper. The challenge for pork producers has been to develop a comprehensive approach that targets all of the areas of emission concern. The pork industry has been progressive in funding emissions research projects and promoting practices and technologies to manage and mitigate emissions in their production systems, according to the paper.

Dairy producers also have a number of different air emission areas of concern, with primary focus on ammonia, odor and greenhouse gas emissions. Dairies in western states have increased concerns with VOC emissions. One challenge faced by dairy producers is the multiple emissions arising from buildings, manure storages and large forage feeding sources. The dairy industry is proactively managing and mitigating emissions by funding air emission monitoring and carbon footprint studies.

The open lots where beef cattle are finished create dust (particulate matter) emissions. Wet weather conditions can create additional concerns with ammonia emissions.

Poultry producers face concerns mostly related to ammonia, but secondarily with particulate matter and bioaerosols. Litter-pack manure handling systems in broiler and turkey operations can lead to increased particulate matter emissions and higher particulate matter levels within barns.

Manure storage and land application of manure have the potential to be large emitters of air pollutants. Storage and application technologies used can play a big role in the significance of odor emission on specific operations, according to the issue paper. Employing anaerobic manure digestion technology can reduce odor, for example, but with higher costs to the producer.

Environmental concerns and regulations for animal agriculture have historically focused on water quality. However, in the past few years, air quality issues have become a growing concern by the public. This has led to increased attention on enforcing air quality regulations for animal agriculture and new, multimedia regulatory efforts.

The full text of the issue paper may be accessed at the CAST website. Download the 24-page paper free of charge online at