INDOOR CHEMISTRY INVOLVING O-3, NO, AND NO2 AS EVIDENCED BY 14 MONTHS OF MEASUREMENTS AT A SITE IN SOUTHERN CALIFORNIA

For more than 1 year, indoor and outdoor O-3, NO, NO2* (NOx - NO), temperature, and relative humidity as well as the air exchange rate have been measured continuously at a commercial building in Burbank, CA. The indoor concentration of a given pollutant is a function of its outdoor level, the air exchange rate, the rate at which it is removed by indoor surfaces, and the rate at which it is produced or removed by indoor chemistry. Several examples of indoor chemistry are inferred from daily and seasonal variations in the collected data. These include homogeneous reactions such as those of O-3 With both NO (fast) and NO2 (slow) and heterogeneous reactions such as those between NO2 and indoor surfaces. The latter ultimately contribute to indoor levels of both HONO and NO and are more likely to be observed in the absence of indoor O-3. Indeed, due to the very rapid O-3/NO reaction as well as other slower reactions, the presence or absence of indoor O-3 strongly influences speciation among the indoor oxides of nitrogen.