Temporal trends of carbon monoxide (CO) and radon ( 222 Rn) tracers of urban air pollution

The use of carbon monoxide (CO) and radon ( 222 Rn) during 1 year continuous monitoring in Bucharest, Romania in relation with other air pollutants (ozone—O 3 , nitrogen dioxide—NO 2 , sulphur dioxide—SO 2 , airborne particulate matter PM10), air quality indices, meteorological variables and planetary boundary layer heights has provided relevant information about lower atmospheric dynamics. Annual average air daily mean CO (328.72 ± 100.02 µg/m 3 ) and 222 Rn (38.43 ± 17.68 Bq/m 3 ) do not exceed the threshold limits established by European legislation. Statistical analysis of CO and 222 Rn temporal trends revealed their suitability as tracer gases for urban air pollution.