"About 75 percent of asthma cases and deaths from smoke pollutants occurred east of the Rocky Mountains in recent years"
"On July 20, a curious haze blanketed the sky across the eastern half of the United States. Sunsets appeared redder than normal, the atmosphere looked gray and dense and air quality plummeted. People from Washington to Philadelphia to New York snapped pictures of the abnormal hues — only to learn that the cause originated from wildfires nearly 3,000 miles away.
As large fires smolder in the western United States, the smoke can travel across the country, blanketing large population centers. Now, a recent study shows that smoke, from both western wildfires and local sources, may be more harmful to residents in the eastern United States than many think.
Over most of the past decade, researchers found that about three-quarters of all smoke-related cases of asthma visits to emergency departments and deaths occurred east of the Rocky Mountains, due to higher population densities. Incidences of asthma-related hospital visits were the highest from April to August."