Beijing’s air pollution surpasses the index

BEIJING - The Associated Press

A woman wears a mask as she visits Tiananmen Square in Beijing. People refused to venture outdoors and buildings disappeared into murky skyline. AP photo

People refused to venture outdoors and buildings disappeared into Beijing’s murky skyline as the air quality in China’s notoriously polluted capital went off the index.

The Beijing Municipal Environmental Monitoring Center said on its website that the density of PM2.5 particulates had surpassed 700 micrograms per cubic meter in many parts of the city. The World Health Organization considers a safe daily level to be 25 micrograms per cubic meter.

PM2.5 are tiny particulate matter less than 2.5 micrometers in size, or about 1/30th the average width of a human hair. They can penetrate deep into the lungs, so measuring them is considered a more accurate reflection of air quality than other methods.

The Beijing center recommended that children and the elderly stay indoors, and that others avoid outdoor activities.

The U.S. Embassy also publishes data for PM2.5 on Twitter, and interprets the data according to more stringent standards.

In the 24-hour period up to 10 a.m. Sunday, it said 18 of the hourly readings were “beyond index.” The highest number was 755, which corresponded to a PM2.5 density of 886 micrograms per cubic meter.