According to the Department of Natural Resources and Environmental Control at approximately 7:58 AM today, Motiva experienced a freeze in a steam drum which caused a release of hydrogen cyanide, anhydrous stabilized hydrogen sulfide, and anhydrous ammonia. Prevailing winds are directing the plume from the Delaware City plant, eastward toward the Delaware River, and at times in the area of Delaware City. Windy conditions redirect the plume intermittently. Due to environmental conditions, the release is expected to continue for several hours, if not until tomorrow.
Environmental monitoring has detected low levels of carbon monoxide and sulfur dioxide. There is no evidence of hydrogen cyanide or anhydrous ammonia.
The levels at which sulfur dioxide is smelled (a rotten-egg odor) is well above the concentration likely to produce serious health effects. Short-term exposures to low concentrations, as detected in this release, may be an irritant to mucous membranes. Exercising asthmatics are sensitive to the respiratory effects of low concentrations. Further information about sulfur dioxide and its health effects can be found at: http://www.atsdr.cdc.gov/toxprofiles/tp116.html
The Division of Public Health recommends that people in the path of the plume or who detect the rotten-egg odor stay indoors with windows closed.