Effect of pet ownership on respiratory responses to air pollution in Chinese children: The Seven Northeastern Cities (SNEC) study

Previous studies examining pet ownership as a risk factor for respiratory conditions have yielded inconsistent results. Little is known about whether or not pet ownership modifies the relationship between air pollutants and respiratory symptoms and asthma in children. In order to evaluate the interaction between pet and air pollution on respiratory health in children, we recruited 30,149 children, aged 2-12 years, from 25 districts of seven cities in northeast China. Parents of the children completed questionnaires that characterized the children's histories of respiratory symptoms and illnesses and associated risk factors. Average ambient annual exposures to particulate matter with an aerodynamic diameter ≤10 μm (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3) were estimated from monitoring stations in each of the 25 study districts. The results showed that among children without pets at home, there were statistically significant associations between both recent exacerbations of asthma among physician-diagnosed asthmatics and respiratory symptoms and all pollutants examined. Odds ratios (ORs) ranged from 1.12 [95% confidence interval (CI), 1.00-1.26] to 1.41 (95% CI, 1.24-1.61) per 31 μg m−3 for PM10, whereas, among children with pets at home, there were no effects or small effects for either asthma or the symptoms. The interactions between dog ownership and PM10, SO2, NO2, and O3 were statistically significant, such that children with a dog at home had lower reporting of both current asthma and current wheeze. In conclusion, this study suggests that pet ownership decreased the effects of air pollution on respiratory symptoms and asthma among Chinese children.