Map Guide — Legend & Layers

This guide explains the symbols, thresholds, colors, and data sources used in FEAST map layers: PM2.5, Ozone, Rx Size, Wildfires, and HMS Fire & Smoke. It also includes tips for turning layers on/off and exploring time ranges.

Fine particulate matter (PM2.5) ≤ 2.5 µm, measured by the AirNow Network. Color-coding uses the daily (24-hour) standard: 35 µg/m³. FEAST shows California monitoring sites.

Data source: https://files.airnowtech.org/
  • Green: PM2.5 < 35
  • Red: PM2.5 ≥ 35

Maximum 8-hour ozone concentration (AirNow). Threshold based on EPA standard: 70 ppb. FEAST shows California monitoring sites.

Data source: https://files.airnowtech.org/
  • Blue diamond: O3 < 70
  • Red diamond: O3 ≥ 70

Prescribed fire burn size as reported by burners, color-coded with a threshold of 50 acres. PFIRS is a California system; FEAST displays California burns.

Data source: Prescribed Fire Information Reporting System (PFIRS)
  • < 50 acres
  • ≥ 50 acres

Wildfires documented by CAL FIRE via the Fire and Resource Assessment Program (FRAP). Records include either a center point or a fire perimeter boundary, depending on availability and period. Coverage: California statewide.

  • Center of Wildfire: Approximate centroid/ignition point of the event.
  • Wildfire Boundary (historical): Mapped perimeter of burned areas for documented incidents.
Data source: CAL FIRE — Fire and Resource Assessment Program (FRAP)
  • Center of Wildfire
  • Wildfire Boundary (historical)

Hazard Mapping System (HMS) provides near-real-time satellite detections of active fires and analyst-drawn smoke plume extents across North America. FEAST includes California-only subsets.

Data source: NOAA Office of Satellite and Product Operations (OSPO)
  • HMS Fire: Satellite fire detections (point)
  • HMS Smoke: Smoke plume boundary (gray outline)

  1. Use the checkboxes to show or hide layers (PM2.5, Ozone, Wildfires, HMS Fire/Smoke, etc.). Checked layers are visible; unchecked are hidden.
  2. Click icons/symbols (fire, smoke, monitor site, etc.) to open a popup with details (site ID, date, value, and more).
  3. Use the time slider or date controls to focus on a specific day or range.