Hoy No Circula

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Hoy No Circula (literally in Spanish: "today it [your car] does not circulate", though known abroad academically as One Day Without a Car) is the name of an environmental program intended to improve the air quality of Mexico City. A similar coordinated program operates within the State of México, which surrounds Mexico City on three sides.

Weekday	Plate's last digit	Sticker color
Monday	5 or 6	yellow
Tuesday	7 or 8	pink
Wednesday	3 or 4	red
Thursday	1 or 2	green
Friday	9 or 0	blue

1 History
2 Emissions testing
3 Property tax
4 Exemptions
5 See also
6 References

[edit] History

Hoy no Circula was started in late 1989, and consisted of prohibiting the circulation of 20% of vehicles from Monday to Friday depending on the last digit of their license plates (see table). The program was planned to apply only during the winter, when air pollution is at its worst. Winter follows the rainy season when thermal inversion, an atmospheric condition which traps smog and pollution close to the ground, increases air pollution noticeably. However, the program was made permanent at the end of the 1990 winter season.

[edit] Emissions testing

Hoy No Circula is coupled with an exhaust monitoring program, known as verificación in Spanish, whereby a car's pollutant emissions are analyzed every six months. A sticker is affixed to each vehicle following an emissions test, indicating whether a vehicle is exempt from the program or not. Based on the result of their emissions test, vehicles are assigned to four classes. Class "00" (for certain new vehicles exempt from emissions testing) and class "0" (generally, cars less than 10 years old and meeting more stringent emissions requirements) are exempt from the Hoy no Circula program. Class "1" vehicles are subject to the Hoy no Circula program. Class "2" vehicles (including all pre-1991 passenger cars) meet weaker emissions requirements, but are subject to both Hoy no Circula and an emergency recall program. In a Phase I air-quality emergency, Class "2" vehicles may drive only on alternate days matching the last digit of their license plate, and in a Phase II emergency or the third consecutive day of Phase I, Class "2" vehicles may not drive at all, barring medical emergency.

[edit] Property tax

If Mexico's vehicle property tax (known in Spanish as tenencia) is not paid, or lapses, the vehicle will not be permitted to have the obligatory emissions testing performed. Such vehicles are then not allowed on the road at all.

[edit] Exemptions

In 1997, to encourage the use of newer, fuel-efficient vehicles equipped with catalytic converters, cars manufactured after 1993 became eligible for an exemption. As a result, by 2003 only 7.6% of vehicles were not allowed to circulate on the average weekday, down from 20% when the program was launched. As of 2008, only vehicles under 11 years old are allowed to receive the 0 or 00 sticker.

Vehicles with plates other than Mexico City or Mexico state plates, including thousands of vehicles with US license plates, are no longer exempted from the license plate restrictions, and are deemed to be of class "2" regardless of age. However, they may submit to emissions testing and obtain an "0" sticker if there vehicles are not more than 5 years old. Any vehicle older than 5 years old will not be allowed to test.

Emergency services, solar or electric vehicles, government and school buses, and the disabled (with permit) are exempt.