A NIOSH Health Hazard Evaluation report presented findings of an agency investigation at an engine machining plant where employees were exposed to metalworking fluids, or MWFs. The union representing the employees had requested the evaluation because of concerns that exposure to MWFs had caused respiratory symptoms and dermatitis among workers.
NIOSH personnel visited the plant in August 2015 and February 2016. Air sampling conducted during these visits confirmed that MWFs were present at levels below occupational exposure limits. However, published studies have found that workers can develop respiratory symptoms from exposure to MWFs below the NIOSH recommended exposure limit of 0.5 mg/m3.
A questionnaire issued by NIOSH investigators revealed that 40 percent of participating employees reported work-related nasal symptoms and 30 percent reported work-related asthma-like symptoms. The highest prevalence of these symptoms occurred among employees who frequently used a spray or compressed air to dislodge metal chips from the equipment they operated. The HHE report notes that “such a practice can increase airborne levels of MWF mist as well as increase the potential for dermal exposure.”
NIOSH investigators also found that employees’ use of personal protective equipment was inconsistent and that some employees wore shorts and sleeveless shirts instead of the long clothes required by the employer. Skin contact with MWFs can cause allergic contact dermatitis, irritant contact dermatitis, and irritation or infection of the hair follicles. More than 40 percent of employees who participated in the NIOSH questionnaire reported dermatitis on at least one part of their body in the month preceding the questionnaire.
Employees’ concerns about air quality at the plant led NIOSH investigators to examine the plant’s ventilation system. The system introduced and exhausted air at the ceiling level, which might not have resulted in adequate mixing of air at the floor level to dilute contaminants. The discovery of droplets of metalworking fluid on the mist collector exhaust led investigators to theorize that the fluid was bypassing the filter.
The report lists several recommendations for both the employer and the employees, including changes to the ventilation system, consistent use of PPE, and elimination of the use of sprays and compressed air to dislodge chips from equipment. The full report is available as a PDF on the NIOSH website.