The CNR-ISAC station in Lecce is located about 4 km (SW) of the urban area and it can be classified as an “urban background” site. The site is located at about 30 km and 80 km from the most important industrial centres of the Puglia Region (Taranto and Brindisi). The observatory is accommodated in a shelter located on the roof of the Institute of Atmospheric Sciences and Climate (Division of Lecce), at about 12 m above the street, inside the University Campus. The observatory is used for the collection of environmental continuous data related to local meteorology, various gaseous pollutants concentration and different atmospheric particulate fraction. The instrumental check, the data acquisition and data analysis are remotely managed through internet. The roof of the shelter is equipped to take real-time meteorological measurements using a radiometer (Kipp & Zonen, mod. CNR4), that measures solar and thermic radiation, and an automatic wheatear station (Vaisala, mod. WXT520) for the main meteorological parameters acquisition. On the roof of the observatory there are sampling probes for gas and aerosol connected to the measurement instruments located inside the shelter. Outside the observatory there is a booth, which hosts the mixtures of pure gases needed for periodic calibration of gas concentration detectors and a telescopic mast to measure particle number concentration and vertical particle fluxes, using the Eddy-Covariance method by an Ultrafine Condensation Particle Counter UCPC (TSI, mod. 3776) and an ultrasonic anemometer Gill R3. The interior of the shelter is equipped with different instruments for atmospheric and environmental measurements:  Heated gas sampling probe (General Impianti srl) with conditioning of temperature to control relative humidity, connected to a 11 valves manifold.  Aerosol sampling probe, PM10 cut-off, with 10 valves manifold equipped with a high volume pump (Mega System srl, mod. X1-Hornet).  Measurements of particle size distribution in the following intervals: • from 8 nm to 800 nm: Scanning Mobility Particle Sizer (SMPS produced by the Tropos- Leibniz Institute for Tropospheric Research, in compliance with Actris specifications). • from 0.28 µm to 10 µm: Optical Particle Counter (OPC FAI instruments, mod. Multichannel).  Particulate sampler (FAI Instruments, mod. SWAM5a Dual Channel) which measures the PM2.5 and PM10 mass concentrations using the measuring principle based on attenuation of β ray.  Measurements of Black Carbon concentrations in atmosphere by a Multi Angle Absorption Photometer (Thermoscientific, mod. 5012).  Measure of atmospheric aerosol back scattering coefficient by a Nephelometer (TSI, mod. 3560).  Measurements of gaseous concentrations, CO, CO2, CH4 and water vapour, by a detector PICARRO (mod. G2401).  Measurements of gaseous concentrations by an ozone automatic analysers (Thermoscientific, mod. 49i) and a nitrogen oxides analysers (Thermoscientific, mod. 42i-TL).  Measurements of the columnar content of gaseous pollutants by a spectrophotometer DOAS which is provided with an external measuring head (located on the observatory roof) connected to the spectrophotometer by optics fibres.  Calibration systems for gas detectors: Multipoint calibrator (Thermoscientific, mod. 146i) used for the nitrogen oxides calibration, ozone generator (Thermoscientific, mod. 49i-PS) for the ozone concentration analyser and zero air generation (Thermoscientific, mod. 146i).  A server station with monitor that communicates with the various instruments and stores the data. The server station operates as a vehicle for the display and the remote data transfer. It is connected to a data logger Campbell Scientific CR1000 with a buffer battery.