Local air quality is a running balance between how much pollution sources emit and how fast wind and controls clear it away.
AQI ~ emissions*(1-controls) / wind_dispersion
- City grid size — city blocks tracked for local air quality.
- Filtration/control coverage — share of blocks with emission controls or low-traffic zones in place.
- Emission source density — concentration of traffic and industrial emission sources.
- Wind dispersion rate — how effectively wind clears accumulated pollution from street level.
London's low-emission zones and similar traffic-control measures have measurably cut roadside NO2 within months of implementation, exactly the mechanism this grid models.