TRENTON Mom’s advice about bundling up in the cold is especially important for the growing number of people with asthma. Cold weather, particularly a shift from relatively mild weather to much-colder air, can trigger dangerous asthma attacks in many people. Precautions as simple as wrapping a scarf around the mouth and nose while outside can spare them lots of wheezing, coughing and anxiety, though. Just as being outside for a while in winter can trigger a runny nose in people who don’t have asthma from skiers to playing children cold air can cause constriction or spasm in the bronchial passages in susceptible asthma patients, said Dr. Leonard Bielory, director of the Asthma and Allergy Research Center at the University of Medicine and Dentistry of New Jersey in Newark. “You can have coughing on the first day and severe asthma (symptoms) in 24 hours,” Bielory said. Vulnerable patients have what he calls “twitchy airways,” which are slightly inflamed all the time, so they go into spasm easily. This time of year also is tough for asthma patients because of the many respiratory infections going around; getting one worsens their asthma. “Viral respiratory infections tend to really light (asthma) up,” said Dr. Fred M. Jacobs, state commissioner of health and senior services. Infections increase chances of an asthma attack, in which the airways swell and tighten, and cells there release histamine and other inflammation-causing chemicals. That narrows and clogs the airways further, limiting airflow and causing the symptoms of an attack: chest tightness, wheezing, trouble breathing and coughing. “There’s an increased incidence of asthma nationwide,” noted Jacobs, a lung specialist who once did a study as a research fellow that showed cold air causes airways to narrow via a nerve reflex pathway. “There’s an increase in asthma mortality,” he added. Reasons are in dispute, but about 30 million Americans, or roughly one in 10 people, now has asthma. Despite effective means to control it, more than 4,250 Americans 1.5 per 100,000 people still die of complications each year. To limit chances of dangerous flare-ups, doctors say limit time out in the cold, use a rescue inhaler shortly before going outside and take it with you, take your asthma controller medicine as scheduled, stay hydrated and avoid respiratory infections and known attack triggers such as smoke and pet dander. If an attack occurs, rush to the doctor or emergency room, they urge. The effect of cold air on asthmatic lungs is even worse during exercise outside, because they are inhaling and cooling the breathing passages at a faster rate than normal, so vulnerable patients should move their workout indoors. The recent warm and damp weather has increased mold levels in some places, exacerbating problems for asthma patients allergic to mold, said Dr. Maria Lania, head of allergy and immunology at Cooper University Hospital in Camden. She estimated she saw a 15 percent to 20 percent spike in asthma patients there last week. Most came in for help because they had serious respiratory infections, either viruses or bacteria such as Mycoplasma, which can cause walking pneumonia. With Sunday’s cold snap, a new group those sensitive to cold will start having problems, Lania said. “It’s common,” she said. “It’s the change in temperature that’s the problem.” Meanwhile, Jacobs has been working to reduce the difference in care levels between the well-off and insured asthma patients and the low-income ones, through a new collaborative at 21 government health centers. They offer free or discounted asthma medicines for children up to 18, education for them and their parents, and follow-up visits. Jacobs noted low-income New Jersey residents are more likely to have asthma, and minorities are two to three times more likely than whites to be hospitalized for asthma complications. That’s probably because they are more likely to live in older housing with mold, dust mites and cockroaches, which can trigger asthma symptoms.