SIP development for an urban nonattainment area impacted by rural fugitive dust

Spokane, Washington was designated a nonattainment area (NAA) for PM10, upon enactment of the 1990 Amendments of the Federal Clean Air Act. A SIP for the area was submitted to the Environmental Protection Agency in December, 1990. This SIP did not demonstrate attainment of the standard. In analyzing why attainment was not demonstrated, the Washington State Department of Ecology's Air Quality Program determined that elevated levels of PM10 during 1988 and 1989 were caused by dust storms from the agricultural region to the southwest of the area. Because there is some evidence that these high values are a temporary occurrence, exacerbated by low precipitation in the region, state and local officials feel they should not, at this time, be considered in calculation of the design values or the control strategy for the NAA. The State Department of Ecology has requested that the values caused by these storms be classified as exceptional events or that a waiver be granted the area under provisions of Section 188(f) of the Clean Air Act Amendments of 1990