NASAL INFLAMMATORY RESPONSES IN CHILDREN EXPOSED TO A POLLUTED URBAN ATMOSPHERE

Southwest Metropolitan Mexico City (SWMMC) preadolescent children have been exposed to a highly polluted urban atmosphere most of their live s. The main objective of this study was to determine by nasal lavage ( NALI the acute inflammatory nasal influx elicited in these children up on exposure to three different polluted days. Ozone, the main criteria pollutant for SWMMC, varied both in the number of hours above the Nat ional Ambient Air Quality Standard (NAAQS), which is 0.12 ppm as a 1-h maximum concentration not to be exceeded more than once per year, and in the maximal concentrations in the preceding three NAL sampling dat es. Nasal neutrophilic influx, the surface expression of the B2 integr in CD11b on the nasal polymorphonuclear leukocytes (PMNs), rhinoscopic findings, respiratory symptoms, and nasal cytologies were evaluated i n the 38 exposed children and in the 28 control children living in a n onpolluted Pacific coast port. SWMMC children had an average daily out door exposure of 7.7 h and complained of nasal mucus secretion, epista xis, intermittent nasal obstruction, diurnal cough episodes, and chest discomfort. Nasal mucosal atrophy by rhinoscopy was present in 37/38, and all children had an abnormal nasal cytology. Exposed children had significantly higher nasal PMNs and nasal PMN-CD11b expression than c ontrols. PMN median values in exposed children were higher than contro ls on all sampling dates (November 12, p < .007; November 17, p < .001 ; and November 24, p < .00001). Interestingly, a lower nasal neutrophi lic response (p < .0004) was recorded in the SWMMC children 18 h after exposure to the highest O-3 concentrations (up to 0.307 ppm) and the largest number of hours with O-3 > 0.12 ppm (7 h). The question of a c ompeting inflammatory response at the bronchioalveolar level with stru ctural damage is raised. These NAL findings underscore the need to res trict outdoor activity in SWMMC children during the months of greater potential exposure to ozone.