Ammonia gas is a chemical compound consisting of hydrogen and nitrogen, with the chemical formula NH3. It is a colorless gas, but is easily identifiable by smell, as it has a pungent odor. Ammonia gas is commonly found in the production of fertilizers and refrigerants, however you are likely to smell it well before it will be harmful to you. The degree of danger that ammonia gas poses varies significantly depending on how much is present, and how long you've been exposed for.
Type: Electrochemical
Range: 0-100 ppm (0.1 ppm resolution)
High Range: 0-500 ppm (1 ppm resolution)
Low Alarm: 25 ppm
High Alarm: 50 ppm
STEL — 15 minute — Short Term Exposure Limit: 35 ppm
TWA — 8 hour time weighted average: 25 ppm
https://www.ccohs.ca/oshanswers/chemicals/chem_profiles/ammonia.html
https://www.health.ny.gov/environmental/emergency/chemical_terrorism/ammonia_tech.htm
https://www.worksafebc.com/en/health-safety/hazards-exposures/ammonia
https://www.foodmanufacturing.com/facility/article/21103964/ammonia-and-the-associated-risks-of-confined-space-entry-incidents-for-food-refrigeration
https://lpelc.org/wp-content/uploads/2019/03/Section-5-Fact-Sheet-Manure-Gases.pdf
https://www.chemicalbook.com/ProductChemicalPropertiesCB9854275_EN.htm