AMARILLO – The air we breathe may have a little more ammonia in it as the years go by, but the general public can rest easy that it is not anywhere close to posing a health threat, according to a Texas AgriLife Research scientist.
Dr. Brent Auvermann, an AgriLife Research and Texas AgriLife Extension Service agricultural engineer, has spent the past four and a half years working with the National Atmospheric Deposition Program, monitoring a site at Canonceta on the rim of Palo Duro Canyon as a part of an ammonia monitoring network.
“Ammonia is anywhere and everywhere; it’s an industrial pollutant. It’s emitted by our bodies and automobiles, and it’s emitted by production agriculture of all kinds,” Auvermann said. “So we don’t know precisely what sources are responsible for the increase, if indeed the trend we’re seeing is even real.”
Since Oct. 30, 2007, the long-term average concentration is about 5 parts per billion, give or take 25 percent, he said.
“That’s a factor of 500 lower than the odor detection threshold, and a factor of 5,000 below any current worker-health standards. The federal government doesn’t even have a public air quality standard for ammonia,” Auvermann said.
“But by now, with about four and a half years’ worth of data in hand, we can start to talk about long-term trends that may be suggesting themselves,” he said.
Auvermann said the low background ammonia concentration in the southern Texas Panhandle, the region represented by the Canonceta site, appears to be increasing ever so slightly over time, at a rate near 2 percent per year.
“That apparent rate of increase is not too different from the human population increase upwind of our monitoring site,” he said.
Even so, population increases alone probably don’t tell the whole story, Auvermann said. “More industrial activity, more agricultural activity, more municipal development – it’s all in the ammonia mix.”
The ammonia monitoring-site field operations require Auvermann to pick up exposed cartridges and deploy fresh ones under a precipitation shelter every two weeks.
The cartridges, known as Radiello samplers, are small filter cartridges impregnated with an acid solution and dried, he said. When exposed to the air, the acid-coated fibers trap any gaseous ammonia that filters through the samplers.
“After we ship the Radiellos to the central lab in Illinois, the lab technicians run a solution through the sampler medium to extract all of the dissolved ammonia,” Auvermann said. “They then analyze that solution to measure the amount of ammonia trapped by each sampler during the two weeks it was exposed to the air.”
He said the lab is also able to estimate the volume of air that passed through the sampler from the number of hours it was exposed between deployment and recovery.
The end result of all of that lab work and computation is known as an “ambient ammonia concentration,” Auvermann said. “Ambient means, essentially, the concentration to which everybody in the area would be exposed if they were all just walking around outdoors.”
An ambient concentration is distinct from an “occupational” concentration, which would be the level of pollutant to which individuals are exposed in a work environment, he said.