Chinese officials are starting to post new data about air quality on the Internet, but already there are questions about the reliability of the information.

The effort by the Beijing Municipal Environmental Monitoring Center comes in response to repeated calls from the public for better information about what exactly is in Beijing's smog-filled air.

The new readings are for PM2.5 — particles that measure 2.5 micrometers or less, smaller even than the average width of a single human hair. Scientists say despite their tiny size, the particles are among the most dangerous because they are able to lodge themselves into the lungs.

Saturday's initial reading, taken from a single monitoring station in the capital, registered between 0.003 and 0.062 micrograms per cubic meter, classifying the air quality as good. But some environmental experts are suspicious.

Consultant Steven Andrews has been studying Beijing's pollution data since 2006. He told the Associated Press that a similar monitor placed at the U.S. embassy in Beijing registered such low levels of pollution only 18 times in the past two years.

Earlier this week, the embassy classified Beijing's air quality as hazardous after it found the level of PM2.5 exceeded its monitor's maximum reading of 500 micrograms per cubic meter.

Chinese officials say they plan to install additional air quality monitors around the city. Until now, officials had based their air pollution readings on the prevalence of particles that measures at least 10 micrometers.