This article assesses the individual and joint impact of pressure, temperature, and relative humidity on the accuracy of atmospheric CO2 measurements collected by unmanned aerial systems (UASs) using low-cost commercial non-dispersive infrared (NDIR) sensors. We build upon previous experimental results in the literature and present a new dataset with increased gradients for each environmental variable to match the abrupt changes found in UAS-based atmospheric vertical profiles. As a key contribution, we present a low-complexity correction procedure to mitigate the impact of these variables and reduce errors in this type of atmospheric CO2 measurement. Our findings support the use of low-cost NDIR sensors for UAS-based atmospheric CO2 measurements as a complementary in situ tool for many scientific applications.