Humidity, hot winds and the decaying Salton Sea have long been been a recipe for nostril and stomach misery during the summer across large swaths of the eastern Coachella Valley. But now, an analysis of 20 years worth of records by a UC Riverside laboratory shows a disturbing new trend: The noxious odor is hanging around at detectable lower levels year-round. … Since Friday, hydrogen sulfide levels have repeatedly exceeded the state recommended level of 30 parts per billion average per hour, in some cases more than double that recommended limit. Air regulators issued an extended odor advisory for the eastern Coachella Valley through Wednesday evening, citing shifting winds off the Salton Sea.