A two-step approach for relating tapered element oscillating microbalance and dichotomous air sampler PM2.5 measurements

Abstract

A method for transforming continuous monitoring (CM) fine particulate matter (aerodynamic diameter <2.5 mm; PM2.5) data (i.e., by tapered element oscillating microbalance [TEOM]) obtained from the Canadian National Air Pollution Surveillance (NAPS) program to meet the data quality objective (DQO) of R2 > 0.8 against the co-located federal reference method (i.e., dichotomous air sampler) is described. By using a two-step linear regression to account for the effect of the ambient temperature, 16 out of the 23 examined sites met the common model adequacy threshold of R2 > 0.8. After the transformation, 20 out of the 23 examined sites met the DQO of R2 > 0.7, as recommended by the U.S. Environmental Protection Agency (EPA). A combined two-step statistical approach was also examined and revealed similar results. The methods described herein show that the CM data can be successfully transformed to meet DQOs for representative sites across Canada using year-round (both summer and winter) data.