NEW YORK – Kids, who grow up with a dog in the house, may be at higher risk of developing asthma if they're also exposed to scond hand smoke or nitrogen dioxide, new research shows. Children exposed to the toxic gas and to dog allergen during their first year of life were nearly five times as likely to have asthma at age seven compared to kids with neither exposure, while dog allergen plus second hand smoke nearly tripled the risk. Most studies of asthma have looked at single risk factors, but in the real world, people often face multiple exposures, Dr Chris Carlsten of Vancouver General Hospital in British Columbia, Canada and colleagues point out in the European Respiratory Journal. To investigate the interplay between such exposures, the researchers looked at 380 children at high risk for asthma who had been followed since infancy. The children were considered to be at high risk because they had at least one close relative with asthma, or at least two close relatives with allergies. The children and their families had been participating in a study of whether reducing exposure to potentially allergy- promoting factors, such as household dust and secondhand smoke, might reduce their risk of developing asthma or allergies. In the current analysis, the researchers compared children's exposure to dog allergens, second-hand smoke (measured by checking their urine for the nicotine by-product cotinine, as well as their umbilical cord blood at birth), and nitrogen dioxide, which is found in automobile exhaust and produced by other types of fuel burning.
