Resumen:
An infrared lidar DIAL technique was used to monitor ozone concentration in Madrid urban atmosphere. Interestingly, we found an unusual increase of ozone concentration due to heavy traffic conditions accompanying the holiday rush despite the prevailing low photochemical activity. Consequently, the usual daily ozone profile shifts towards the later hours. A direct and quantitative correlation between ozone pollution and human activity such as the excess of vehicle traffic accompanying summer holiday departures from Madrid city was observed. This new type of information will be useful in the development of local models to understand the dynamics underlying urban pollution.