Physical Conditions in Low Ionization Regions of the Orion Nebula
  We reexamine the spectroscopic underpinnings of recent suggestions that [O I] and [Fe II] lines from the Orion H II region are produced in gas where the iron-carrying grains have been destroyed and the electron density is surprisingly high. Our new observations show that previous detections of [O I] 5577 were dominated by telluric emission. Our limits are consistent with a moderate density (10^4 cm^{-3}) photoionized gas. We show that a previously proposed model of the Orion H II region reproduces the observed [O I] and [Fe II] spectrum. These lines are fully consistent with formation in a dusty region of moderate density. 
J. A. Baldwin, A. Crotts, R. J. Dufour, G. J. Ferland, S. Heathcote,   J. J. Hester, K. T. Korista, P. G. Martin, C. R. O'De...