Evaluating real-time particulate matter instruments against gravimetric and size-resolved references to advance residential wood heater development

Abstract

Residential wood heater certification testing relies on time-integrated gravimetric filters that obscure the transient particulate matter (PM) generation events central to heater certification. Continuous PM instruments could support advancement of heater technologies, but most are developed for ambient air and may struggle under the high concentrations, dynamic transients, and variable aerosol properties of wood combustion. This study evaluated five continuous particulate matter (PM) instruments spanning light scattering (TSI DustTrak II 8530, Thermo MIE pDR-1500, Particles Plus 8306), inertial mass (Thermo Scientific 1405-D TEOM), and triboelectric charge (Sintrol S203) against gravimetric filters and size-resolved reference concentrations across three heater types and two operating phases. No single instrument performed well across all conditions. The DustTrak II and pDR-1500 demonstrated the most consistent temporal tracking (r ≥ 0.87 and r ≥ 0.79, respectively) but substantially overestimated integrated PM mass during cordwood combustion and require gravimetric correction for quantitative use. The TEOM performed closest to the gravimetric reference during pellet high-burn phases but exhibited sustained negative cumulative mass during cordwood tests. The Particles Plus and Sintrol showed the weakest overall performance across all conditions. These results support the continued advancement of residential wood heater technologies by identifying conditions under which each instrument provides more or less reliable PM data, and may help inform instrument selection for laboratory testing for product development and field studies for verification.