INVESTIGATION AND REMEDIATION OF DIESEL CONVERTED TROLLEY BUSES ASSOCIATED WITH EXTENSIVE FUNGAL GROWTH AND HEALTH COMPLAINTS

Fifteen bus drivers, operating diesel converted trolley buses, experie nced symptoms including watery and itchy eyes, rhinorrhea, and headach es. A total of 49 buses were labeled as ''problem buses'' and operator s refused to drive them. An investigation identified high fungal count s in some problem buses (>70,000 colony forming units [CFU]/m(3);n = 3 ) compared with control buses (<220 CFU/m(3); n = 4). The predominant species were Penicillium and Cladosporium (1/1). Remedial measures, in cluding washing with a 0.17% solution of sodium hypochlorite and an oz one treatment, were not successful. Because fungal species are heat se nsitive, two buses were subjected to a heat treatment of 55 degrees C for 4 hours. In one bus the fungal spores of Cladosporium appeared to be more hear sensitive than the spores of Penicillium. At this point t he interior of one bus was completely renewed and another was given a formaldehyde treatment followed by heat treatments. Both strategies re duced fungal counts to 190 from >107,000 CFU/m(3) for the former and t o 270 from >71,000 CFU/m(3) for the latter. Only the interior of the m ost heavily contaminated buses were refurbished prior to the heat trea tment, which was done on ail problem buses. Ail buses are still in act ive service 5 years later. The most frequent health symptoms reported by 88 exposed bus drivers were headache (36%), blocked/runny/itchy nos e (26%), nausea (26%), and dry irritated throat (25%). No chronic heal th effects have been reported after 5 years, although some of these co mmon fungal species are known to be opportunistic pathogens.