Abstract: A CO2 laser photoacoustic spectrometer intracavity configuration has been built and tested. The application was for determining the NH3 gas concentration on exhaled breath of scavengers on the Landfill. The off-line experiment was conducted through non-invasive sample method using exhaled breath. Exhaled breath sample was taken by three daily variations of the morning, mid-day and post-day. The data was analized by multicompound gas method using the software of excel, origin and scilab. The result from the photoacoustic spectrometer intracavity configuration with the strongest frequency resonance(1650±5) Hz at biomarker gas occured on absorption lines 10R14, 10P14 and 10P16. The lowest detection boundary from ammonia is (23.3±0.5) ppbV. The highest ammonia concentration from scavengers was (2904±1) ppbV occured in the early morning and the lowest concentration was (1089±1) ppbV in the post-day. Meanwhile, on healthy volunteers, the highest ammonia concentration was (1676±1) ppbV in the morning and the lowest ammonia concentration was 377±1) ppbV in the mid-day. It shows the contamination of air ambien caused the increasing concentration of biomarker gas in the human body.