Background: Bob Claypool, 52, was a Fresno dentist.Why he left: Doctors told him he had asthma and allergies, although they could never find what he was allergic to, he said. Drugs didn't help much.Now: Bob sold his Fresno dental practice in 2005 and moved to a condominium in San Diego. The coastal air has been good for his health, he said. For the past year, he's not needed asthma medicine.