Ambient Air Monitoring Active Report

To convert from ppb (parts per billion) to ppm (parts per million), you divide the ppb value by 1,000, because 1 ppm is equivalent to 1,000 ppb. For example, 500 ppb is 0.5 ppm (500 / 1000 = 0.5), and 100 ppb is 0.1 ppm (100 / 1000 = 0.1). 

Examples

2,500 ppb: 2,500 / 1,000 = 2.5 ppm 

100 ppb: 100 / 1,000 = 0.1 ppm

500 ppb: 500 / 1,000 = 0.5 ppm

You can also use any free online converter. https://www.inchcalculator.com/ppb-to-ppm-converter/

Risk Based on Level of Exposure of H2S

0.0002-0.3ppm Odor Detection threshold, 0.0014ppm Daily exposure likely to be without risk, 0.02ppm 15-364 days of exposure with minimal risk, 0.07ppm 14 days or less of exposure with minimal risk, 10ppm 10-minute exposure limit, 20ppm Ceiling Limit, 50ppm Peak 10-min exposure limit, 100ppm Immediately dangerous to life or health, 40,000-440,000ppm Explosive (lower and upper limits)

What does H2S gas smell like at low concentrations?

At low concentrations, hydrogen sulfide (H₂S) smells distinctly like rotten eggs, a warning sign of its presence, detectable in air from parts per billion (ppb) to low parts per million (ppm). This familiar odor comes from decaying organic matter in places like sewers, swamps, and landfills, but at higher levels, it can quickly overwhelm your sense of smell, causing olfactory fatigue, making it undetectable even as it becomes more dangerous.