Comparing Gravimetric and Real-Time Sampling of PM_2.5 Concentrations Inside Truck Cabins

Abstract

As part of a study on truck drivers’ exposure and health risk, pickup and delivery (P&D) truck drivers’ on-road exposure patterns to PM_2.5 were assessed in five, weeklong sampling trips in metropolitan areas of five U.S. cities from April to August of 2006. Drivers were sampled with real-time (DustTrak) and gravimetric samplers to measure average in-cabin PM_2.5 concentrations and to compare their correspondence in moving trucks. In addition, GPS measurements of truck locations, meteorological data, and driver behavioral data were collected throughout the day to determine which factors influence the relationship between real-time and gravimetric samplers. Results indicate that the association between average real-time and gravimetric PM_2.5 measurements on moving trucks was fairly consistent (Spearman rank correlation of 0.63), with DustTrak measurements exceeding gravimetric measurements by approximately a factor of 2. This ratio differed significantly only between the industrial Midwest cities and the other three sampled cities scattered in the South and West. There was also limited evidence of an effect of truck age. Filter samples collected concurrently with DustTrak measurements can be used to calibrate average mass concentration responses for the DustTrak, allowing for real-time measurements to be integrated into longer-term studies of inter-city and intra-urban exposure patterns for truck drivers.

Keywords:

• gravimetric
• PM_2.5
• real-time
• spatial variability
• traffic
• temporal
• truck driver

ACKNOWLEDGMENTS

The authors would like to acknowledge the contribution of the other members of the Trucking Industry Particle Study: Francine Laden, Eric Garshick, Jaime E. Hart, Douglas W. Dockery, and Frank E. Speizer. We would also like to thank LaMont Byrd and the International Brotherhood of Teamsters Safety and Health Department, and the participating companies. The research presented here was funded by NIH/NCI R01 CA90792 and HEI 4705-RFA03-1/04-1.

Notes

^A Truck route numbers correspond to those in Figure 3.

^B Routes with high particulate exposure peaks

^C Truck driver smoked.

^A Standard deviation shown in parentheses.

^B Geometric standard deviation shown in parentheses.