Means the maximum concentration of a chemical in air that is safe for the operator. In a period of 15 minutes, and has been repeated no more than 4 times in 1 day each time must be at least 1 hour.
The mean maximum concentration of chemicals in the air are safe for workers. Take the 15 minutes and was repeated four times in less than one day each must be at least 1 hour.
Means the maximum concentration of chemicals in the air, safe for workers will be. รับในระยะ time 15 minutes and get unique not exceeding 4 times in 1 days. Each time apart with at least 1 hours.