Authorities in Sao Paulo said morning rush-hour traffic was about the same as it was a week ago.

The city of 18 million people and 5.5 million cars is notorious for its traffic jams and air pollution caused in part by auto exhaust, in spite of measures to restrict use of cars. The city has a world-class subway system, but it only serves limited areas.

Many of the city's richest inhabitants commute to and from work by helicopter. Sao Paulo has the third-largest fleet of helicopters among cities worldwide, after Tokyo and New York.

In Rio de Janeiro, Brazil's second-largest city, few knew about the observance, ecologists said, making little difference in traffic.

TERRA.WIRE