Actor and sometime tenor Paul Sorvino was studying an opera score in his Manhattan studio one afternoon four years ago when his wife, Lorraine, telephoned. Their 3-year-old son, Michael, was sick. His face was puffy, he had vomited and he was complaining that he couldn't breathe. Lorraine thought it might be asthma.

Sorvino's stomach tightened. The affable, ursine star of 25 feature films, including That Championship Season, Reds and most recently Turk 182!, had suffered from asthma for 15 years. It had, in part, sidetracked him from a promising operatic career and menaced his acting prospects. He jumped into his car and raced home. The parents bundled their son's tiny, limp body off to the doctor.

Four years later Sorvino's eyes still betray the fear he felt at nearly losing his son. But suddenly Michael, now 7 and a whirlwind of little-boy energy, careens into the family sun-room on a warm spring morning, then races outside to play basketball. He has been free from full-fledged asthma attacks for three years. Sorvino, 46, has just written a book, How To Become a Former Asthmatic (William Morrow, $9.95), a blueprint of the program that led to Michael's recovery from the respiratory disease that afflicts more than nine million Americans.

Rather than rely solely on the various medications that were prescribed for Michael after his attack, Sorvino immediately began to teach him the exercises that he had used to cure his own asthma. "These are yoga breathing exercises that have been around for thousands of years," he says. "They teach you to fill your lungs up from the bottom, where they have the most capacity. It enables a person to begin dealing with his affliction in an organized way."

Not surprisingly, Sorvino's book has met with skepticism from parts of the medical establishment. Dr. Talmadge E. King, head of clinical services at the National Jewish Hospital/National Asthma Center in Denver, cautions against viewing it as a cure. "Asthma is a complex disease," he says. "We believe a total program of medical, psychosocial, drug and rehabilitation therapies is required to control the disease."

Sorvino presents case histories of people he has helped over the last 20 years with the twice-daily 15-minute exercises—from the soundman's son on the set of Off the Wall to actor John Ritter's son, Jason, to movie critic Jeffrey Lyons. In his son Michael's case, it took all of Sorvino's formidable artistry to maintain the small boy's interest in the necessary regimen. He and Lorraine devised games that would encourage Michael to practice using his lungs properly. "We'd pretend my fingers were candles that he had to blow out. Other times I would make my hands into the shape of a bird and in a little voice tell him I was too weak to fly. Michael would blow air under its wings. Each time he would get the bird into the air, it would thank him and fly away into the imaginary horizon."

The burly actor had his first asthma attack at age 10. The youngest of three brothers, he had been spirited to California from Brooklyn by his mother, a piano teacher who was in the midst of marital difficulties with his father, a Neapolitan garment worker. The frightened boy got his first attack the day they arrived and was put to bed for four days. After a year and a half his father arrived to take him back to Brooklyn. He didn't see his mother again until his parents started to communicate seven years later.

Early on Sorvino had set his heart on an operatic career, but the asthma interfered. He decided on acting instead and won a scholarship to the American Musical and Dramatic Academy, where he met and married fellow student Lorraine Davis. The asthma struck again just before his 1965 Broadway debut in a show called Sayour with Chita Rivera, Robert Burr and Herb Edelman. Sorvino feared he would have to drop out of the show. One day after rehearsal he mentioned his asthma to Edelman and Burr, both of whom regularly practiced yoga. Edelman remarked casually, "Oh, that can be cured." Recalls Sorvino, "They showed me [the exercises] in less than an hour. I awoke the next morning and apart from the bronchitis, which felt like a slight chest cold, my breathing was completely free."

In the 14 weeks since the publication of his book, Sorvino has been besieged with queries, many from desperate asthma sufferers. "I've been talking during the publicity tour to 40 people a day who are so ill they can barely talk on the phone. It's become a responsibility. I want to make sure that asthmatics know about the exercises." He laughs. "It would be ironic—but rewarding—if after all these years of acting, I become best known as the author of an asthma prevention book."