Intestinal metaplasia is also a common in Barrett esophagus. It this condition it is the esophageal squamous epithelial cells that undergo metaplasia. Approximately, 60% of esophageal cancers diagnosed in the U.S. stem from focal intestinal metaplasia.
Ozone Emission Sources. Emissions contributing to ozone formation come from many areas. The main emission sources categories are: On-road - cars, trucks, and buses. Off-road - aircraft, locomotive,etc. Non-road - construction, agricultural equipment, etc. Point - cement and power plants.
Ozone is a natural gas that is found in two different layers of the atmosphere. One layer, called the troposphere, is at the Earth's surface where we live. Ozone in the troposphere is bad because it dirties the air and helps make smog, which is unhealthful to breathe.