Aerosols containing Legionella pneumophila generated by shower heads and hot-water faucets.

Shower heads and hot-water faucets containing Legionella pneumophila were evaluated for aerosolization of the organism with a multistage cascade impaction air sampler. Air was collected above two shower doors and from the same rooms approximately 3 ft (91 cm) from the shower doors while the hot water was running. Low numbers (3 to 5 CFU/15 ft3 [0.43 m3] of air) of L. pneumophila were recovered above both shower doors, but none was recovered from the air in either room outside the shower door. Approximately 90% (7 of 8 CFU) of the L. pneumophila recovered were trapped in aerosol particles between 1 and 5 micron in diameter. Air was collected 1 to 3 ft (30 to 91 cm) from 14 sinks while the hot water was running. Low numbers (1 to 5 CFU/15 ft3 of air) were recovered from 6 of 19 air samples obtained. Approximately 50% (6 of 13 CFU) of the organisms recovered were trapped in aerosol particles between 1 and 8 microns in diameter. Shower heads and hot-water taps containing L. pneumophila can aerosolize low numbers of the organism during routine use. The aerosol particle size is small enough to penetrate to the lower human respiratory system. Thus, these sites may be implicated as a means of transmission of L. pneumophila from potable water to the patient.