The authorities of the Mexico City metropolitan area declared on Tuesday an "extraordinary environmental contingency" after the pollution level exceeded the tolerance threshold.

The Environmental Commission of the Megalopolis issued the alert after the Index of Metropolitan Air Quality registered 158 points for PM2.5, exceeding the threshold of 150 points.

The commission asked the public to avoid outdoor activities and vigorous exercise as well as reduce car use and facilitate working from home.

Recently, the populated metropolis has been vexed by poor air quality due to numerous forest fires, caused by high temperatures common in May.