Controlling gas and vapor concentrations outside the explosive limits is a major consideration in occupational safety and health.

It measures the vapor concentration at two different locations in the diffusion path.

At very high vapor concentrations, acetone is irritating and, like many other solvents, may depress the central nervous system.

Vapor concentrations are also measured at two or more intervals during the pilot study to estimate initial vapor concentrations of a full-scale system.

The vapor concentration, vapor extraction rate and vacuum data are also used in the design process to select extraction and treatment equipment.

In high doses pyridine has a narcotic effect and its vapor concentrations of above 3600 ppm pose a health risk.

It determines the time required to reduce a known vapor concentration existing in a closed space to a lower vapor concentration.

"The alarm on the mass spectrometer sounded with a full and distinct spectrum across the monitor for a lethal vapor concentration of mustard," he said.

Even vapor concentrations immediately penetrate the skin.

It does this by varying the vapor concentration surrounding the sample and measuring the change in mass which this produces.