Indoor chemistry involving O3, NO, and NO2 as evidenced by 14 months of measurements at a site in Southern California.

For more than 1 year, indoor and outdoor O3, NO, N02 (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 03 with both NO (fast) and N02 (slow) and heterogeneous reactions such as those between N02 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 O3. Indeed, due to the very rapid O3/NO reaction as well as other slower reactions, the presence or absence of indoor O3 strongly influences speciation among the indoor oxides of nitrogen.