For years, worldwide environmentalists, as well as Beijing citizens, have become increasingly concerned about China's capital city's air pollution - and the ways in which it may negatively impact the health of thousands, or even millions, of residents.

In the past, some residents have reported shortness of breath, asthma attacks, or even lung cancer diagnoses; many believe the city's smog has led to such considerable health defects.

In response to previous allegations regarding smog, Beijing environmental authorities have finally released air quality data measurements.

According to the authorities, the city recently had readings of PM2.5, showing that the air's particulate matter was roughly 2.5 micrometers in size.

Throughout their measurement processes, Beijing's environmental authorities tended to report findings that ranged from 0.003 to 0.015 milligrams of particulate matter per cubic meter, shocking many environmentalists who live outside of Beijing.

"In all of 2010 and 2011, the U.S. Embassy reported values at or below that level (0.003mg/m3) only 18 times out of over 15,000 hourly values or about 0.1 percent of the time," said Steven Andrews, an environmental consultant who has studied the city's pollution levels in the past.

Andrews added, "PM2.5 concentrations vary by area so a direct comparison between sites isn't possible, but the numbers being reported during some hours seem surprisingly low."

For further information concerning the city's air pollution levels, please visit this link.