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APCD monitoring report: 15 PM10 exceedences in 2025 concentrated in Santa Maria; network expansion planned
Summary
The district’s 2025 annual air quality report shows 15 state PM10 24‑hour exceedences—recorded at the Santa Maria station and driven by high winds—no ozone exceedences of the state and federal 8‑hour standards, and plans to deploy roughly 140 low‑cost sensors countywide with EPA funding.
Sage Swain of the APCD monitoring section presented the district’s 2025 annual air quality report on June 25, summarizing monitoring network changes, exceedences and planned sensor deployments.
Swain described the county’s network of 12 stations (six industrial sites, five state/local air monitoring stations or SLAMS, and one special‑purpose PM2.5 monitor). He reported 15 exceedences of the state 24‑hour PM10 standard (50 µg/m3), all recorded at the Santa Maria station and attributable to high winds in the Santa Maria Valley; Swain noted the apparent recent increase in exceedences is partly an artifact of the Santa Maria station being offline during some prior years.
The district recorded zero exceedences of state or federal 8‑hour ozone standards in 2025; as of Jan. 1, 2026 the county remains designated non‑attainment transitional for the state ozone standard. Swain also explained that EPA changed breakpoints for PM2.5 in May 2024, which increased the number of days categorized as 'moderate' even though air quality itself has not necessarily worsened.
Monitoring investments include recent additions of two PM2.5 EBAM monitors and plans to petition EPA to convert a special‑purpose monitor in Carpinteria ("Karp" in the record) to a permanent SLAMS monitor. The district has been awarded an EPA Inflation Reduction Act grant and pass‑through funds from the California Air Pollution Control Officers Association to procure and deploy more than 140 low‑cost PM2.5 sensors across the county—targeting schools and community locations—and is conducting outreach to partners for installations.
Swain said the district is performing a one‑year PM speciation study in the Santa Maria Valley to better understand PM10 sources; sampling locations include Guadalupe and other valley sites. He also reported replacement of the Galita station structure (1984 vintage) with a 10x10 conex box, with equipment removed in May and the new structure installed in June for service expected to resume in July.
Board members noted a labeling typo on the attached packet (a map titled as 2024 that appears to be 2025 material) and asked staff to track EPA breakpoint changes in longer‑term trend displays so future viewers are not misled by shifts in categories.
Swain closed by noting updates to the district’s online forecast map (expanded forecast areas and hourly station updates) and invited community partners to request sensor deployments via the district.
