Performance of cabin air filters used in waste collection trucks

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 one of the most useful 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 (UFP), 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 UFP to micron-sized particles. The issue of preventive CAF replacement should also be addressed.Implications: Waste collection truck (WCT) drivers spend most of their time in micro-environments contaminated by traffic-related emissions and work-related bioaerosols. No previous study has assessed the performance of cabin air filters (CAF) on WCTs as a function of particle size, and their evolution in the event of clogging under real waste collection conditions. This research highlights the fact that WCT cabin air filters exhibit highly variable, and only low to medium, minimum collection efficiencies. Waste collection conditions also accelerated the filter clogging compared with literature data on nonprofessional use of CAFs. Given the size of the particles to which WCT drivers are exposed and their adverse health effects, this study demonstrates the need for more effective and reliable protection. This implies the development of specific regulations and standards for CAF performance and testing, including systematic measurements of fractional collection efficiency over a wide range of particle sizes, from ultrafine to micron-sized particles. These regulations should also explore the definition of more precise and adapted guidelines for CAF replacements to prevent the decrease in air exchange rate and the release in the cabin of deposited particles or of fraction of microbial colonies. Finally, all professional drivers, not just WCT workers, could benefit from such specific regulations.