Gases - Chlorine

Chlorine-like odors in indoor air are common when disinfecting products are used. Most of the time chlorine gas is not the problem. Typically what is being smelled are compounds called chloramines. These are the by-products of the disinfecting products. For example, there can be a rather irritating chlorine smell in indoor swimming pools, especially when people are swimming. This is not usually from chlorine gas. Most of the time the smell is from chloramines. If the swimming pool is tested regularly and within specifications for pH, alkalinity, and available chlorine, it is highly unlikely that chlorine gas is being produced unless there is a mechanical problem.

Chlorine gas is not usually used for disinfecting because it is hazardous. Most of the time hypochlorite bleach products, as well as others, are used. These contain "available chlorine". Available chlorine does not necessarily mean chlorine gas. They may give off small amounts of chlorine gas "as is", but if these products are acidified they can give off rather large amounts of chlorine gas.

Sampling

1. Check for chlorine gas especially if the gas is being used - it has a PEL, TLV, and REL. Samples are run by NIOSH 6011 on a silver membrane filter.

2. Check for chlorine dioxide gas if it is being used - it has a PEL, TLV, and REL. The collection method follows OSHA ID-202 using an impinger of carbonate/bicarbonate and KI.

3. Chloramines are collected on special filters and reported out as nitrogen trichloride using an in house procedure and analyzed as total chloride by IC. 

For additional help and details reference our online sampling guide or call the laboratory.