Performance of cabin air filters used in waste collection trucks.

Abstract

Exposures to traffic-related emissions are known to be responsible for diseases and increased mortality. Waste collection truck (WCT) drivers spend most of their time in microenvironments contaminated by these emissions and are also exposed to some pathogenic bioaerosols. To prevent WCT driver exposure, the cabin air filter (CAF) appears as a useful piece of equipment. No standard prescribing CAF efficiency levels for general or professional use was developed. Existing test procedures overlook particles smaller than 300 nm, such as diesel soot or certain bioaerosols, and no previous study has specifically addressed WCT cabin air filters or their clogging under real waste collection conditions. The aim of this work was to evaluate for a range of particle sizes including ultrafine particles (UFPs), the collection efficiency and pressure drop of the CAF media used in WCTs and to study their evolution after clogging under real waste collection conditions. All the tested CAF models exhibited the typical U-shape curve of fractional collection efficiency with low to medium minimum collection efficiency ranging between 1.3% and 42.5%, depending on the filtration velocity. Statistical analysis indicated that CAF media are relatively homogenous across their filtration area and that variations in efficiency and pressure drop were mainly due to differences in clogging levels or initial state conditions. Compared to data available for private vehicles, CAF clogging appears to be more severe under waste collection conditions. Given the diversity of particulate contaminants, the low to moderate performances of current CAFs, and the exposure of WCT drivers, this study highlights the need for improved and more-reliable protection. It is therefore essential to develop specific regulations or standards for CAFs, including systematic measurements of fractional collection efficiency over a broad particle size range, from UFPs to micron-sized particles. The issue of preventive CAF replacement should also be addressed.Implications: Waste collection truck (WCT) drivers are exposed to traffic-related emissions and bioaerosols. No previous study has evaluated cabin air filter (CAF) performance in WCTs across particle sizes or their clogging under real conditions. This research shows CAFs have low to medium minimum collection efficiencies and clog faster in waste collection environments than in private vehicles. Given the health risks of ultrafine and micron-sized particles, improved protection is needed. Regulations should require systematic efficiency testing over a wide particle size range and define preventive replacement guidelines to maintain air quality and prevent particle or microbial release. All professional drivers could benefit.