We're excited to announce a major expansion of the Trace AQ platform coverage, adding 15 new metropolitan areas and crossing the 50-city milestone for our operational forecast network. This expansion brings Trace AQ's industry-leading air quality forecasting to major population centers in North America and Europe that were previously outside our coverage area.
New North American Coverage
In North America, we've added full 4-day AQI and PM2.5 forecast coverage for Chicago, Denver, Minneapolis, Portland (Oregon), Salt Lake City, and Toronto. These additions complete our coverage of the 15 most populous North American metropolitan areas, a milestone that has been a strategic priority since our Series A funding.
Chicago and Minneapolis are of particular interest for wildfire smoke monitoring given their position in the central continental US — they are frequently impacted by smoke transported from western wildfires in late summer and fall, and by smoke from Canadian boreal forest fires in spring and early summer. Our physics-based transport modeling performs particularly well for these long-range smoke transport scenarios, giving Chicago and Minneapolis residents 3–4 day advance warning of smoke events that previous tools couldn't reliably forecast beyond 24 hours.
Denver presents unique air quality challenges that we've invested significant effort in modeling accurately. The urban heat island effect in Denver creates afternoon ozone concentrations driven by a complex interplay of mountain-valley circulation, traffic emissions, and photochemical reactions that vary dramatically by season and time of day. We worked with researchers at Colorado State University to validate our ozone forecasting methodology for the Front Range urban corridor before announcing coverage.
European Expansion
Our European expansion adds London, Paris, Amsterdam, Berlin, and Madrid to the coverage network. European air quality forecasting presents distinct challenges from North American operations: higher population density, more complex emission inventories dominated by diesel vehicle emissions and residential wood burning, and different regulatory frameworks that affect how data is reported and shared.
We're integrating data from the Copernicus Atmosphere Monitoring Service (CAMS), the European equivalent of the EPA's air monitoring network, as our calibration anchor for European coverage. CAMS provides modeled analyses and forecasts for PM2.5, PM10, NO2, O3, CO, and SO2 across Europe at 10 km resolution, which we then downscale and correct using our proprietary methodology.
London and Paris were particularly high-priority additions given the volume of customer requests from European healthcare and research institutions. We've been running both cities in internal beta for six months and are confident in forecast quality ahead of this general availability announcement.
Enhanced PM10 and NO2 Forecasting
Alongside the geographic expansion, we're releasing enhanced PM10 and NO2 forecast capabilities for all existing covered cities. PM10 (coarse particulate matter) is particularly relevant for dust events, construction activity, and road resuspension, and has distinct health effects from PM2.5. NO2 is a critical respiratory irritant with strong associations with asthma exacerbations, particularly in children, and is primarily emitted by vehicle traffic and power generation.
Our NO2 forecasting uses a combination of TROPOMI satellite observations (a European Space Agency instrument with near-global daily coverage) and traffic flow modeling to produce spatially explicit NO2 predictions at 500-meter resolution within metropolitan areas. This level of spatial detail allows meaningful differentiation between air quality conditions near major arterial roads versus residential side streets — a distinction that matters enormously for chronic exposure assessment.
What's Next
We're targeting coverage of 100 global metropolitan areas by end of 2026, with Southeast Asian and South American cities as the next geographic priorities. We're also actively developing support for SO2 monitoring around industrial point sources, which is particularly relevant for petrochemical refinery communities and coal-fired power generation corridors.
All 50+ cities are available in the Trace AQ API today. Existing API customers with global coverage licenses will see the new cities automatically without any configuration changes. New customers interested in European coverage can request a demo through our contact page.
