High levels of air pollution can cause increased incidences of asthma attacks, respiratory infections, lung cancer and even death, a U.S. physician says. Dr. Jonathan Weissler, director of the James M. Collins Center for Biomedical Research at The University of Texas Southwestern Medical Center in Dallas, said a summer of triple-digit temperatures will worsen air quality. The combination of sunlight and heat essentially bakes the atmosphere and the various airborne chemical compounds within it. This chemical concoction mixes with naturally occurring nitrogen oxides in the air to create smog, or ground-level ozone, Weissler said. \"Oxides of nitrogen and sulfur, smoke, and ozone are irritants of the airways and can worsen any pre-existing lung condition,\" Weissler said in a statement. \"People with chronic lung disease should try to minimize their time outdoors when air quality becomes extremely poor.\"