An influx of neutrophils (PMNs), a primary feature of acute inflammation, has been associated with the development of lower lung disorders, such as emphysema and idiopathic fibrosis, as well as airway hyperreactivity and increased mucus secretion. It was previously established that an acute inflammatory response in the upper respiratory tract of humans could be studied by analysis of nasal lavages (NL), which is inexpensive, non-invasive, and atraumatic. However, the relationship of the cellular changes in the upper respiratory tract to changes in the lower airways has not been thoroughly investigated in humans. Here the cellular changes detected in the NL with those detected in the bronchoalveolar lavage (BAL) taken from the same individual have been compared. Ten subjects were exposed to either filtered air or 0.4 ppm ozone (O3), with exercise, for 2 hrs. The NL was done prior to, immediately following an 18 hr post exposure, while the BAL was done only at 18 hr post exposure. A significant increase in PMNs was detected in the NL immediately post exposure to 03, (7.7-fold increase; p=.003), and remained elevated in the 18 hr post-03 NL (6.1-fold increase; p<.001).