Mexico City businesses warned Tuesday that traffic restrictions have cost them more than $300 million since April as authorities banned nearly half of vehicles again due to high smog levels.

It was the second time since last month that the government kept 40 percent of the city's 5.5 million vehicles off the streets because air pollution exceeded acceptable limits.

The government imposed temporary rules on April 5 that ban 20 percent of cars, depending on their plate numbers, every day until June 30, with the number doubling on days that ozone levels surpass a measurement of 150 points.

The latest alert was activated on Tuesday because levels exceeded 160 points on Monday. Air quality was still bad on Tuesday afternoon, prompting authorities to announce that 40 percent would remain off the road again on Wednesday.

The Chamber of Small Services and Tourism Commerce of Mexico City said the temporary measures have so far cost 5.4 billion pesos, or more than $300 million, to city residents, small shops and service providers whose transportation has been restricted.

Arturo Espinoza, manager of the bakery La Universal off a busy downtown avenue, said his business is losing around $1,700 per day because "our bread distribution is affected."

Nearby, Ana Belen Lopez said her small taco restaurant has lost between 30 and 40 percent of revenue in the past month.

"There are one- or two-day delays in receiving supplies," she said in front of a pan with hot oil.

- Corruption blamed -

The chamber of commerce urged the authorities to find other ways to improve the air quality in the city of more than 20 million people and 5.5 million vehicles.

The vehicle ban "clearly does not solve the problem, it generates high costs for the population and it weakens the city's economic activity," the chamber said in a statement.

The group said officials should not wait until the end of the extraordinary measures on June 30 to present a strategy to combat air pollution, such as modernizing public transport.

The chamber said the city must combat "corruption" at vehicle emission test centers that have allowed polluting cars to stay on the roads.

Ignacio Hernandez, who was serving fresh juices and manning the cash register at another downtown restaurant named Costillas El Sitio, said the supply center is 17 kilometers (10 miles) away.

The restaurant has lost some $1,700 because it can't go to the supply shop as often as before and it has been forced to rent transportation when their regular vehicle's license plate is banned.

"It has affected us a lot because the products around here are expensive," Hernandez said.