Academic journal article Journal of Environmental Health

Grass Seed Field Smoke and Its Impact on Respiratory Health

Academic journal article Journal of Environmental Health

Grass Seed Field Smoke and Its Impact on Respiratory Health

Article excerpt


Despite 30 years of protests by local citizens claiming that the burning of thousands of acres of grass in Eastern Washington and Northern Idaho has negatively affected their health, grass field burning continues. Recently, pressure to alter the practice has grown as a result of a convergence of concerns among several diverse political, social, and economic groups. These groups are concerned about the potential health impacts of grass smoke, as well as about economic impacts on tourism. They include an area Chamber of Commerce, the Spokane County Medical Association, the American Lung Association, the Washington Environmental Council, an extremely active Spokane citizens' group, and the Spokane County Air Pollution Control Authority (SCAPCA) (1-5). Given the numbers of opponents, why does the practice of grass field burning continue? In part, the burning continues because no research has been undertaken to identify its potential health impacts. Furthermore, Kentucky bluegrass growers have not found any alternative methods of stimulating grass seed production that are as effective as field burning. Without studies identifying the health hazards of grass smoke, and with grass seed sales constituting a $75 million industry in the inland Northwest, economics have taken precedence over health concerns. In fact, the right to burn grass seed fields was written into a 1991 revision of the Washington State Clean Air Act (6).

In early discussions of the health effects of grass field burning, the president of the Inland Grass Growers Association (IGGA) stated that grass smoke was 80 percent steam and presented no health hazards to area residents, unlike wood smoke, which contains harmful airborne particulates. Opponents contend that the smoke produced by burning grass results in harmful airborne particulates and that grass burning is a virtually unregulated practice, unlike wood burning (7).

Airborne particulates are measured by diameter in microns (i.e., [PM.sub.2.5] refers to particles equal to or less than 2.5 microns [[micro]meter] in diameter). Particles 10 [[micro]meter] in diameter or more ([PM.sub.10]) do not remain airborne for long and are usually filtered by the nasal passages. The smaller the size of the particulates (especially 5 [[micro]meter] and under), the longer the particulates circulate in the air, and the deeper they penetrate into the alveolar cells of the lungs.

In addition to particle size, health concerns relate to the chemicals that are usually associated with the process of incomplete combustion (8,9). It has been shown that the concentration of polycyclic aromatic hydrocarbons (PAHs) in suspended particulates is inversely correlated to particle size and that 47 to 70 percent of PAH in smoke is contained in the [PM.sub.2.0] fraction (10,11).

The importance of air pollution in the pathogenesis of bronchial asthma and other pulmonary diseases has been of interest for decades. Considerable epidemiological evidence implicates fine-particulate air pollution, especially [PM.sub.10] and [PM.sub.2.5], as a trigger that exacerbates respiratory conditions in some individuals with asthma and chronic obstructive pulmonary diseases (12-16). The biological mechanism for these effects is as yet unknown, but [PM.sub.10] particulate matter has been demonstrated to have free radical activity and proinflammatory effects in lung tissue in vivo and in vitro, as well as immunosuppressive properties (17,18).

The pro-inflammatory effects appear to negatively affect individuals suffering from a variety of respiratory conditions such as asthma, chronic bronchitis, cystic fibrosis, and emphysema. Individuals whose respiratory conditions include a reactive airway disease (RAD) component appear to be most negatively affected. RAD is often diagnosed as chemically induced asthma and may account for up to 30 percent of diagnosed asthma cases. Chemically induced asthma occurs in response to triggers such as chemical irritants present in the smoke produced by the open burning of biomass (19-24). …

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