Impacts of air pollution on plant anatomy in urban areas were studied using two different tree species, namely birch tree (Betula papyrifera) and sweetgum tree (Liquidambar styraciflua), at two globally different locations with different air pollution levels. Wuhan City in China is considered as a commercial center for central China while Union City in USA is located close to New York City, one of the mega cities in the world. Stomatal density measurements were used to record the response rate of the two different tree species to different levels of air pollution. We found significantly higher stomatal densities for samples collected in China regardless of the tree species while the air pollution levels in China was worse compared to the ones in USA. Our observation suggests that the studied tree species likely have developed metabolic resilience mechanisms to cope with the chronic high level of air pollution exposure.