Ozone is a highly reactive gas that is a pervasive air pollutant at ground level. It is a major component of urban smog, forming when emissions from mobile and industrial sources interact with sunlight. The study of the effects of long-term ozone exposure on lung complex carbohydrates, described in this report, was one of eight laboratory studies supported by the NTP/HEI collaborative agreement. In addition to studying lung and nasal structure and function, investigators studied other constituents of lung connective tissue. Dr.