The common cold causes 80 percent of asthma attacks in children and 60 percent of attacks in adults, experts say, and British researchers say they may have found why. Researchers found that an antiviral protein called interferon-beta was lacking in the lung cells of asthma patients. Low amounts of the protein mean that the cold virus can trigger or worsen asthma symptoms. Experts say restoring the levels of this protein may help stop the asthma attacks that are triggered by common viruses.