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Update on dairy air quality emissions

Kathryn Walker Published on 20 July 2011

This spring the Western States Dairy Producer Trade Association held the Western Dairy Air Quality Symposium in Sacramento, California. Researchers from across the country presented the latest information about dairy farm air emissions.

The data was informative and overwhelming, but key take-home messages from the symposium were:
1. The dairy industry has increased its understanding of on-farm air emissions, but there is still more to learn.
2. Regulations are likely to occur but hopefully not to the extent the industry expected.
3. There will always be concern from the public about dairy farms impacting the environment.



Increased understanding
Over the last few years, the dairy industry, along with other livestock groups, has invested a significant amount of time, money and energy to measure on-farm emissions. As part of the National Air Emissions Monitoring Study (NAEMS), the data will be used by the EPA to help determine future permitting and reporting requirements.

The data collection was necessary; otherwise regulations would have been developed based upon extremely old and out-of-date data. Although NAEMS produced a lot of valuable information, there is still more to be learned and several questions yet to be answered.

Future regulations
It is very difficult to predict what air emissions regulations will look like in the future for dairy farmers. The EPA is still analyzing the data from NAEMS.

However, a lot of what will affect the industry will depend on the state’s ability to maintain attainment for clean air standards. When the state fails to meet clean air standards as a whole, dairy farms will be targeted with permitting and/or reporting requirements.

Some states have moved ahead with policies to address regional issues. For instance, the Yakima Regional Clean Air Agency has started a project that requires dairy farmers to choose from a list of best management practices as an effort to reduce targeted emissions.


One best management practice might be applying fresh water to a field that has received a recent manure application as a means to reduce ammonia emissions.

One on-farm emission that was not originally considered a problem but is gaining more attention is volatile organic compounds (VOCs). The industry has recently learned that silage is one of the strongest VOC sources on the farm and when VOCs react with nitrogen oxides (combustion engines are the largest source of nitrogen oxides), ozone is produced.

Ozone has a negative impact on the respiratory system, so VOCs are something the industry needs to watch closely.

Public concern
Those in agriculture understand the value associated with living next to a farm. Farmers provide local jobs and preserve open spaces, not to mention provide a safe, affordable, reliable source of food. Unfortunately, not all see farms in this light. Many view farms as noisy, smelly and dusty.

The public will continue to have concerns about potential environmental impacts from agriculture. Nuisance concerns, such as odors, will tend to be on the forefront of challenges the dairy industry will have to address.

The Oregon Right-to-Farm law continues to remain strong, but the number of groups and individuals who want to challenge this law is growing. This is a reminder about the importance of continuing to be a “good neighbor” to lessen the amount of fuel for this growing fire.


One action might be to consider odor or air emission reduction measures when making a management decision. Researchers have recently developed tools that can help livestock operators determine the areas of their operation where opportunities exist to make changes resulting in reduced air emissions. One such tool is the National Air Quality Site Assessment Tool (NAQSAT).

NAQSAT provides producers the opportunity to evaluate their current management practices and compare potential emissions and odor mitigation practices for their farm in the privacy of their own home or office. NAQSAT is available online at PD

—Excerpts from ODFA, Oregon Dairy Farmers Association Spring 2011 newsletter