Beijing's landmark building in crazy bad smog

Another day where the Beijing smog level was 'beyond scale'. Originally the scale of PM2.5 particicle measurement ends at 500. The scale goes as follows (based on what the US embassy installed on its premises here in Beijing):

The scale and thresholds are based on the U.S. EPA standards at airnow.gov

Good	0-50
Moderate	51-100
Unhealthy for Sensitive Groups	101-150
Unhealthy	151-200
Very Unhealthy	201-300
Hazardous	>300

'Hazardous' is described as 'Health warnings of emergency conditions. The entire population is more likely to be affected'. We had 517 this morning labed "crazy bad." Given the fact that we had more than 900 two weeks back we may consider this Beijing day "lovely".

Beijing, 29 January 2013.