You could probably use mass spectrometry on plant extracts or plant ash from collected plants from the site in questions, and then collect the same plant from another non-contaminated location and compare the difference in chemicals you consider 'pollutants' in the mass spec samples.

I suggest to use ICPMS on plant extract to detect the particulate matter level as compared to control similar plants of nearby areas. You may also use carbon monoxide detector near the planting sides as well as gas sampler for gasses such as sulfur dioxide, nitrogen oxides, ozone etc to measure the air pollution of the place.

Thank you so much J.C. Tarafdar and Carl Alexander Frisk. this is very helpful