Stable carbon isotope ratios and radiocarbon (14C) concentrations in samples of pine wood (AD 1975–2012) from 3 sites, as well as needles (AD 2012–2014) collected from 15 sites, in a heavily urbanized area in proximity to heavy industrial factories in Poland were analyzed as bio-indicators of CO2 emissions. The sampling sites were located at different distances from point sources. The stable isotopic composition was determined using an isotope ratio mass spectrometer, and the 14C concentration was determined using a liquid scintillation counter and an accelerator mass spectrometer. Spatial and temporal variability of δ13C and Δ14C in tree ring cellulose and needles was noted in all regions. A negative correlation between δ13C tree ring cellulose and anthropogenic CO2 emissions has been observed. The ratio of δ13C in tree ring cellulose to δ13C in needles created in the same year is equal to 1.2 at the investigated sites.