Occupational exposure in swimming pool facilities related to disinfection by-products (DBPs) has been an issue for the last 15 years. Trichloramine (NCl3) and trihalomethanes (THMs) are DBPs formed in swimming pool water following a reaction between organic matter containing nitrogen or organic or inorganic matter, and chlorine. Due to its volatility, trichloramine can easily evaporate into the air and cause nausea and irritation of the eyes and upper airways. Symptoms are likely to be particularly pronounced in those suffering from asthma. Chloroform is the dominant THM in swimming pool atmospheres and is classified by the International Agency for Research on Cancer (IARC) as being possibly carcinogenic to humans. There are no adverse health effects reported among swimming pool employees due to occupational exposure levels of THMs found in the air at swimming pools.

There is no OEL for trichloramine adapted in Sweden, but some reference values and recommendations based on stationary measurements at the pool side are available. In 2006, the World Health Organisation (WHO) recommended a reference value for trichloramine of 500 μg/m3. The Swedish OEL for chloroform is 10 000 μg/m3.

This thesis describes research into the occupational exposure to airborne trichloramine and THMs in eight Swedish indoor swimming pool facilities and the investigation into the prevalence of adverse health effects, manifesting primarily as ocular and respiratory symptoms.

Concentrations of trichloramine and chloroform in Swedish indoor swimming pool facilities were found to be in the same range or lower compared to previous studies in other countries. The trichloramine concentrations varied between <1 and 240 μg/m3 for the personal sampling and between <1 and 640 μg/m3 for the stationary sampling. Personal trichloramine levels in the high-exposure group were more than 60% higher compared to the corresponding stationary measurements. The exposed group had a higher frequency of self-reported ocular and nasal symptoms compared to the controls. A significant difference in the concentration of exhaled FENO over a work shift with an increase in the exposed group, indicated acute airway inflammation due to respiratory irritant agent exposure. Although a dose-response effect could not be established, the results indicate an elevated risk of occupational health problems in indoor swimming pools and calls for an OEL to be established, based on personal sampling.

Indoor swimming pool facilities often use chlorine for pool water disinfection. Chlorine can also contribute to the formation of unwanted disinfection byproducts (DBPs). Trichloramine and trihalomethanes (THMs) are DBPs formed in swimming pool water and swimming pool air causing occupational exposure. Trichloramine can cause ocular and airway irritation, while some THMs are potentially carcinogenic. Bacterial endotoxins may also cause adverse respiratory effects among swimming pool workers. 

The overall aim of the study was to measure levels of trichloramine, THMs and endotoxins in the air at conventional, habilitation and rehabilitation, and adventure swimming pool facilities, and to investigate adverse ocular and respiratory effects among indoor swimming pool workers.

Trichloramine and THM levels in air were comparable to previous studies. Endotoxin levels in air were low compared to the reference value. Trichloramine concentrations in personal samples were approximately half as high as those measured in stationary samples - an important consideration for a future Swedish occupational exposure limit. The adventure facilities had the highest trichloramine levels while the conventional facilities had the highest THM levels. The adventure workers also reported more ocular and respiratory symptoms compared to referents (office workers) and had a lower FEV1/FVC ratio indicating airway obstruction. Workers both in conventional, and in habilitation and rehabilitation facilities exhibited a difference in FeNO levels compared to referents, implying airway inflammation.

The occupational exposure and adverse health effects found in indoor swimming pool environments emphasizes the importance of a personal based Swedish occupational exposure limit for trichloramine in air.