Odor advisory issued for Coachella Valley
This advisory is in effect Monday, September 21, and will expire at midnight tonight.
The South Coast Air Quality Management District has issued an odor advisory today for the Coachella Valley due to elevated levels of a gas that smells like rotten eggs. That gas – hydrogen sulfide – is associated with natural processes occurring in the Salton Sea.
Sunday evening, hourly average concentrations of hydrogen sulfide (H2S) reached 46 parts per billion downwind of the Salton Sea – at a monitor close to the shore, in an area with little population. The monitor in Mecca, a more populated community further downwind, has not exceeded the state standard of 30 parts per billion at this time. While the H2S is not expected to remain over the state standard for long, odors are likely to be present in the area at times tonight and tomorrow. South and southeasterly winds are likely to occur at times today, potentially bringing H2S odors to other areas of the Coachella Valley at times.
The state standard for outdoor levels of hydrogen sulfide is 30 parts per billion averaged over one hour. At that level, most individuals can smell the odor and some may experience symptoms such as headaches and nausea, or respiratory and nasal irritation. However, the symptoms associated with this level of exposure are temporary and do not cause any long-term health effects. Humans can detect hydrogen sulfide odors at extremely low concentrations, down to a few parts per billion.
SCAQMD monitors hydrogen sulfide at two locations in the southeastern Coachella Valley – one very close to the Salton Sea and the other in the community of Mecca. There is increased potential for Salton Sea odors to occur as the winds shift, especially in the summer months in the early morning and late afternoon, or as thunderstorms occur over the southwestern U.S. deserts.
