February 21, 2012
Several years ago, CLF fellow D’Ann Williams, DrPH, was traveling through Yakima Valley, Washington, and was struck by an indescribable smell. The Valley is home to a great number of dairy cows in high-density operations—72 percent of the dairy facilities in the Valley have more than 500 cows each. (A point of reference: in the nation as a whole, only three percent of all dairy operations are that big.) The smell inspired a study, with colleagues Patrick Breysse, PhD, and other Center affiliates*, and it was published last fall in Environmental Health. The study measures the concentration of airborne pollutants in homes close to dairy operations, and the pollutants include particulate matter (PM) and ammonia. Many airborne contaminants are unregulated, and the health effects of exposure are unknown. Recently, I was able to talk with Williams about her research and her recommendations.
What’s important about this paper?
This was the first paper to measure contaminants associated with dairy facilities in community homes in Yakima Valley. In the last 40 years, the number of dairies in the Valley has not changed much, but the number of animals in the facilities has increased very much with the concentration of dairy facilities.
What did you expect to find, and what did you find?
We expected to find high rates of cow allergen, ammonia, and particulate matter (PM) in homes close to the facilities that we defined as a buffer zone of one-quarter of a mile. And we did find that. But we were surprised to find these same contaminants at homes that were up to the three-miles away. . Also, in the distal homes, we found that the difference in indoor and outdoor levels of ammonia are similar to results that you see in urban environments—where the outdoor concentrations are significantly lower those found indoors. But for the homes that were close, the outdoor concentrations were not significantly lower than the indoor values. You expect higher concentrations indoors based on human activities and other anthropogenic contributions to ammonia, but here in the homes close to the dairies the outdoor levels were high too, suggesting that indoor levels may be highly influenced by the outdoor sources.
Does the study demonstrate a health effect?
There were no health-related data collected in this study. Any health-related conclusions are conjecture based on other studies that have collected self-reported symptoms and decreased quality of life indicators. The study demonstrates that these pollutants appear in measurable quantities in ambient communities near and potentially far from dairy facilities. Coarse PM associated with agricultural, rural areas [in size between PM-10 and PM-2.5] is filtered out through the upper respiratory system, and can result in sinusitis, nasal polyps, and rhinitis. It can also trigger asthma symptoms and allergic responses that affect quality of life.
What’s the urgent message of the study?
These dairy facilities influence the environment outside of them, beyond the fence lines of the facility. It’s obvious that they influence communities very close to them, but we found high rates of pollutants three miles from the facilities.
How is the air in these kinds of communities currently monitored?
There are few rural air quality monitoring sites in the United States. However, there is a lot of monitoring in cities, but there are no real PM monitoring programs in rural areas. Current National Ambient Air Quality Standards only regulate concentration levels of PM, without looking at the composition of the PM. But composition is important. PM can be composed of allergens and biologically active materials like endotoxins and bacteria. And current standards only look at the size of PM—but the size of a particle may not be the best marker of its effect. Rural air quality monitoring programs that examine the composition of health related pollutants are critical to understanding the impact of these facilities on rural health.
What would you like to see happen?
I’d like the EPA to establish a rural monitoring program, where they look at not only the size of the PM but also the composition and speciation, where they look for metals, chemical composition, biologically active components and endotoxin. I’d like to see public health agencies establish a health effects monitoring program in rural communities that critically evaluates respiratory, GI, mental health and other health endpoints, in rural communities as well.
Can you tell me more about the smell you noticed in Yakima Valley?
The smell is an overwhelming presence. It’s indescribable. It’s almost metallic. I was driving on the highway and hit a certain point where it really hits you like a wall … one of the people in the car was sleeping, and the smell woke her up.
What practices contribute to the smell and the presence of pollutants?
The concentration of the animals into barns and stall and definitely, the distribution of cow waste—liquid spraying of manure, the distribution of solids, where a truck with a rotating blade throws the solids on farm land. Some facilities use spray cannons to spray lagoon liquids; they drive it all over the Valley in tanker trucks. Dust is a more serious issue, because of the dusty environment of Yakima Valley. It’s desert-like, a steppe-like environment, like scrubland. It’s highly irrigated to support agriculture and the Valley is also subject to wind inversions that pick up the dust and re-suspends it in the air.
How did you collect the samples?
We vacuumed dust—beds, shelves, soft pieces of furniture. We used filters and gas monitors. We analyzed the filters for cow allergen and didn’t have filters for measuring airborne endotoxin. Cow allergen was our surrogate for evaluating exposure to dairy related pollutants.
Has this paper struck any emotional chords?
There has been some negative response from industry and agricultural engineers questioning our methods. I think this is a very emotional issue for people who are directly subjected to these exposures. In addition, people are protective of their jobs, and there are so many different agricultural crops in the Valley; there are a lot of people employed there in agriculture, migrant workers and also migrant workers that have settled there, many people don’t want to get on the bad side of the dairies.
There are efforts in the Valley now to attempt to address the concerns of the public about the contribution of these facilities to groundwater, surface water and air pollution. Unfortunately, efficient monitoring programs are expensive and labor intensive and regulatory agencies have had difficulty finding the manpower and funding to conduct continuous monitoring of these industries. Industrial animal production business groups want to prevent the adoption of regulations, but in the absence of regulations industry itself must do a much better job at policing their operators and guaranteeing remedy for communities that are negatively affected by poorly managed facilities and operators that do not follow best management practices.
*The paper, “Airborne cow allergen, ammonia and particulate matter at homes vary with distance to industrial scale dairy operations: an exposure assessment,” was published in Environmental Health, 2011. Authors are D’Ann Williams, Patrick Breysse, Meredith McCormack, Gregory Diette, Shawn McKenzie, and Alison Geyh.