eachers and administrators at schools near the Salton Sea have grown accustomed to helping students with asthma, often keeping inhalers on hand in case dusty air triggers an attack. A new survey of the families of first- and second-graders at four schools in the Imperial Valley confirms that the children are suffering from alarmingly high rates of asthma and other respiratory problems.  The survey was carried out by researchers from the University of Southern California’s Keck School of Medicine, who are focusing on the health of children near the shrinking lake.