A PULSED CONDENSATION PARTICLE COUNTER FOR
COST EFFECTIVE MONITORING OF ULTRAFINE AIRBORNE PARTICLES
ABSTRACT
This project will develop and validate a new approach for affordably monitoring the number concentration of
ultrafine airborne particles. Ultrafine particles are specifically implicated in health, and yet are not detected by
lower-cost sensors. Our approach is a Pulsed Condensation Particle Counter that uses adiabatic expansion
combined with single particle counting. Our Phase I results demonstrate that this approach is reliable over
months of continuous operation, with ±10% agreement with expensive, research-grade condensation particle
counters. Our target is an affordable portable instrument, priced at a fraction of the cost of current instruments,
that measures the particle number concentration with known accuracy and precision. The envisioned
commercial instrument will include a commercial optical counter and report ultrafine particle number
concentration and estimated PM2.5 mass.
This Phase II project will improve the performance of the Phase I system, refine the supporting components,
and integrate the electronics and components into a compact system. The complete prototype system will be
tested under both laboratory and field conditions. Instrument precision and accuracy over a range of particle
sizes and concentrations will be evaluated with monodispersed, laboratory aerosols, using particle sizes
ranging from 5 nm to 2500 nm, and concentrations from near zero to several hundred thousand per cubic
centimeter. Instrument robustness will be evaluated through stress-testing at extremes in temperature (5°-
40°C) and humidity (5%-95%). Monitoring performance and stability will be tested through comparison with
collocated benchtop instruments over weeks of unattended operation. Measurements under field conditions
will be conducted in collaboration with a local university exposure study. Validation as a monitor will be done in
collaboration with an air monitoring district. The objective is a compact, cost-effective monitor with a particle
detection limit below 5 nm, with precision of ±10% for concentrations between 10 - 104/cm3, and precision of at
least ±15% for concentrations reaching 105/cm3, and data recovery of at least 90%.
