WHEN THE DUST RISES IN NORTH SHORE, a small farmworker town at the edge of the Salton Sea, Jacqueline Pozar’s nose often starts to bleed. Then her teacher at Saul Martinez Elementary School in nearby Mecca calls her mom, Maria, and asks her to come pick up her daughter. Jacqueline is seven years old. “I feel really bad because I can’t do anything for her,” Maria Pozar says.