Immediately dangerous to life or health

The words immediately dangerous to life or health or IDLH mean that chemicals in the air could be high enough to be bad for a person's health. The high amount of chemicals in the air (their concentration in ppm/ppb)1 millionth (1:106) is 1 μL nerve gas/L air, 1 billionth (1:109) is 1 nL {ammonia, CO, radon}/L air could cause quick injury or death. The concentrations in the United States are set by NIOSH and OSHA. Many equations are used to find the "lethal dose", which is also called LD50: mg substance inhaled per kg body weight. NIOSH then publishes the numbers that show how much of a chemical is bad for humans.

IDLH numbers have been used to help people choose the right respirator.

 Related pages 
 MAC at rest or work: maximum allowable concentration
 NIOSH
 OSHA

 References 

 Other websites 
 IDLH values www.cdc.gov May 10, 2019
 Respiratory protection www.osha.gov nr 1910.134(b)

Category:United States Department of Health and Human Services
Category:United States Department of Labor