TagAir Quality Monitors(75)

UFPs (ultrafine particles, <100nm) measured as PNC (particle number concentration) using SMPS instruments. Unlike PM2.5, UFPs are not currently regulated by EPA or WA state.

PSCAA Monitoring Team: Update on ongoing UFP monitoring at 10th & Weller (Seattle) and North Sea-Tac Park (Sunset Park). WA state-funded program launched 2024.

Nov 14, 2024: two SMPS instruments at 10th & Weller show close agreement in measured particle size distributions, validating instrument precision before field separation.

July 18, 2024 monitoring at 10th & Weller: particle size distribution and black carbon time series showing co-varying peaks throughout the day.

Worldwide scatter plot: PM2.5 mass concentration and particle number concentration are not linearly related. Monitoring PM2.5 alone does not capture UFP exposure levels.

SMPS combines DMA (Differential Mobility Analyzer) and CPC (Condensation Particle Counter) to measure particle size distributions from 5 to 1,000 nm.

Planned next steps: relocate second SMPS instrument to North Sea-Tac Park (Sunset Park); establish data analysis partnership with University of Washington.

Both SMPS instruments operating side-by-side at 10th & Weller since September 24, 2024, to validate measurement consistency before deploying second unit to Sea-Tac site.

PSCAA Air Quality Programs-UFP (October 2024): Real-time SMPS and UFP count data at Seattle 10th & Weller A station, October 10, 2024.

PSCAA Air Quality Programs-UFP (October 2024): Hour-of-day average UFP at 10th & Weller, summer 2024. Highest concentration during morning rush hours; particle size increases by midday.