Overview
- Authorities did not declare an environmental contingency on Saturday, May 23, so the fourth‑Saturday Hoy No Circula rules ran normally after morning readings showed air quality as “acceptable” with a moderate risk from NO2 and PM2.5.
- Under the Saturday rules, vehicles that cannot circulate between 05:00 and 22:00 include those with holograma 2, holograma 1 with even plate endings (0,2,4,6,8), cars with foreign plates and provisional permits.
- Exemptions include emergency and public transport vehicles, motorcycles, electric or hybrid cars with holograma 0 or 00, and vehicles for people with disabilities.
- The Comisión Ambiental de la Megalópolis (CAMe) can declare a Phase 1 contingency at short notice and that declaration would trigger Doble Hoy No Circula, which tightens limits further and can affect some holograma 0/00 vehicles depending on engomado and plate endings.
- The Hoy No Circula program covers all Mexico City alcaldías and 18 adjoining State of Mexico municipalities, noncompliance can draw fines of 20–30 UMA (about 2,346–3,519 pesos), and drivers are advised to follow hourly updates from CAMe and Sedema.