I am assuming radon here as you did not specify.  There are self sampling tests that you can send in.  These vary in price and are found at most home improvement stores.
See:
http://extension.psu.edu/natural-resources/water/drinking-water/water-testing/pollutants/reducing-ra...

https://www.google.com/url?q=http://extension.psu.edu/pests/ipm/childcare/word-docx-for-ipm-pests/ra...

And: https://www.google.com/url?q=https://www.unce.unr.edu/programs/sites/radon/files/pdf/BuildRadonOutNV...

Thanks, G.