In 2009, nearly one in 12 Americans were diagnosed with asthma. In addition to increased diagnoses, asthma costs grew from about 53 billion U.S. dollars in 2002 to about 56 billion dollars in 2007, about a six percent increase. The explanation for the growth in asthma rates is unknown, according to the CDC.

    Asthma is a lifelong disease that causes wheezing, breathlessness, chest tightness, and coughing, though people with asthma can control symptoms and prevent asthma attacks by avoiding things that can set off an asthma attacks, and correctly using prescribed medicine, like inhaled corticosteroids. The report highlights the benefits of essential asthma education and services that reduce the impact of these triggers, but most often these benefits are not covered by health insurers.

    "Despite the fact that outdoor air quality（质量,品质） has improved, we've reduced two common asthma triggers -- secondhand smoke and smoking in general -- asthma is increasing," said Paul Garbe, chief of CDC 's Air Pollution and Respiratory Health Branch. "While we don't know the cause of the increase, our top priority is getting people to manage their symptoms better."Asthma triggers are usually environmental and can be found at school, work, home, outdoors, and elsewhere and can include tobacco smoke, mold, outdoor air pollution, and infections linked to influenza, cold-like symptoms, and other viruses.

    According to the report, asthma diagnoses increased among all demographic groups between 2001 and 2009, though a higher percentage of children reported having asthma than adults (9.6 percent compared to 7.7 percent in 2009). Annual asthma costs in the United States were 3,300 dollars per person with asthma from 2002 to 2007 in medical expenses. About two in five uninsured and one in nine insured people with asthma could not afford their prescription medication.

    "Asthma is a serious, lifelong disease that unfortunately kills thousands of people each year and adds billions to our nation's health care costs," said CDC Director Thomas Frieden. "We have to do a better job educating people about managing their symptoms and how to correctly use medicines to control asthma so they can live longer more productive lives while saving health care costs."(本文由在线英语听力室整理编辑)