It could be that you are living in the forest or a wooded area. The official measurement happens on Mauna Loa, purposefully chosen to be without vegetation or soil or nearby human activity.

See https://gml.noaa.gov/ccgg/about/co2_measurements.html

> The observatory is surrounded by many miles of bare lava, without any vegetation or soil. This provides an opportunity to measure “background” air, also called “baseline”” air, which we define as having a CO2 mole fraction representative of an upwind fetch of hundreds of km. Nearby emission or removal of CO2 typically produces sharp fluctuations, in space and time, in mole fraction. These fluctuations get smoothed out with time and distance through turbulent mixing and wind shear. A distinguishing characteristic of background air is that CO2 changes only very gradually because the air has been mixed for days, without any significant additions or removals of CO2. Another common word for emissions is “sources”, and for removals, “sinks”.