Smoke from Pasture Burning


Prescribed pasture burning is a long-standing practice in Kansas to enhance the nutritional value of the native grasses and reduce weeds and brush. Flint Hills ecosystem covers 13 Kansas counties. Two million of the 4.5 million acres in the Flint Hills are burned each year. Burning is necessary, but smoke is problematic. Smoke from these fires, particularly in the Flint Hills, has contributed to air quality problems in downwind communities, including Kansas City and Wichita. The smoke plume also has impacted several states to the east of Kansas according to satellite images. The smoke plume impacted several states to the east of Kansas according to satellite images. Smoke constituents of particulate matter and ozone precursors are the main concern. In recent years, the Kansas Ambient Air Monitoring Network has recorded elevated concentrations of both particulate matter and ozone in ambient air during the time of intensive pasture burning. Particulate matter causes haze/visibility concerns and fine particulates in smoke can contribute to significant health problems for young children and the elderly people with respiratory illnesses. Ozone may aggravate asthma symptoms and impair the breathing of healthy individuals. Ozone is the key pollutant of concern in Kansas City and Wichita communities, due to monitored exceedances of air quality standards. The smoke plume from pasture burning has been the subject of intense discussion and a controversial issue for pasture burning management.

Trends of related air quality regulations

The National Ambient Air Quality Standards (NAAQS) are evolving as new standards are developed for ozone and fine particulates. In 2006, the fine particulate 24-hour PM2.5 (Particulate matter that less than 2.5 µm in equivalent aerodynamic diameter) standard was reduced from 65 to 35 μg/m3. In 2008, the 8-hour ozone standard was reduced from 0.080 to 0.075 ppm. In 2010, EPA proposed the new primary ozone standard be reduced to a range between 0.060 to 0.070 ppm. The continued lowering of ozone and fine particulate standards, together with the Regional Haze Regulations are demanding changes in air quality management. In nonattainment areas where air quality violates the NAAQS (e.g. in Kansas City), control measures must be implemented, which could add significant regulatory and economic burdens. Air quality regulators are under pressure to quantify all sources that are contributing to poor air quality at a time of ever-tightening standards. Prescribed pasture burning is not going to be allowed the relative inattention of the past and will be accounted for as carefully as other major pollution sources. Prescribed pasture burning needs to negotiate and compete for limited and decreasing allowable impacts on air quality. The interagency linkages between land managers and the air quality regulatory community are growing. Managers of future prescribed pasture burning will need to utilize all available information to reduce the smoke hazard.