Randy Stanley, an acoustic specialist for the National Park Service, concluded the plenary session by briefly discussing some NPS steps to procure low-noise products. The complication for the national parks is that the natural ambient sound level is the baseline against which impacts will be evaluated, but ambient levels vary greatly from one park to the next. Superintendents at each park are responsible for identifying what levels of noise constitute acceptable impacts, but they, too, face the problem of defining what is acceptable. One park may need to accommodate battlefield sounds, while at another even a single automobile may be inappropriate.

In 2008 the Park Service began putting together information on how to reduce noise through low-noise products, using data from a Noise Pollution Clearinghouse (www.nonoise.org), the Consumers Union, and other sources. In 2009 an NPS guidance pamphlet was circulated to all the parks, with plans for updating over time (NPS 2011). The guidance recognizes that purchasers consider a wide variety of information when making decisions, including ease of use, power, flow rate, efficiency, weight, and engine design. At Glacier National Park, for example, large amounts of snow need to be removed from roadways each year, requiring the use of heavy equipment. And the lightweight chainsaws used by the Park Service (because they need to be carried long distances into the backcountry) are often noisier than others. Given such considerations, the pamphlet provides information on various strategies for making low-noise purchases.

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