Evaluating Low-Cost Instrumentation for Ultrafine Particle Number Monitoring in Urban and Suburban Environments

AARON COLLINS, Rob Caldow, OpenAeros LLC

     Abstract Number: 541
     Working Group: Instrumentation and Methods

Abstract
Ultrafine particles (UFPs, dp <100 nm) are primarily produced through combustion processes and are prevalent in urban and suburban environments, especially near roadways, biomass combustion sites, and aviation hubs. Although UFPs contribute minimally to overall particle mass, they constitute the majority of particle number and are strongly associated with adverse health outcomes, including cardiovascular, pulmonary, and neurological effects. However, widespread regulatory monitoring of UFP number concentration remains limited due to the high cost and complexity of conventional condensation particle counters (CPCs).

This study evaluates the performance of relatively low-cost instrumentation for measuring UFPs in real-world urban and suburban settings. A low-cost instrument package, comprising an OpenAeros OpenCPC™ for total number concentration and another OpenCPC with a catalytic stripper for solid number concentration enables direct comparison between total and combustion-derived solid particle counts. Additionally, total number concentrations from optical particle counters (PMS5003, Piera IPS7100, Alphasense OPC-N3) are compared against the CPCs to assess correlation and suitability for cost-effective UFP monitoring.

The findings highlight both the strengths and limitations of low-cost optical sensors and lower-cost CPCs for number-based monitoring. By harnessing affordable, open-source instrumentation, this research aims to advance UFP monitoring methodologies and promote broader adoption of number concentration measurements across research, regulatory, and community applications.