SEN0220 - calibration

I have the serial version of this sensor and I'd like to know how to calibrate it. I see there are serial commands for "zero" and "span", but doubt it would be wise to use those, since I don't have appropriate atmospheres to put the sensor in.

I read that I should simply place it outdoors for several hours and it will self-calibrate. Is this correct? We're monitoring an office environment and would like to know the readings are within spec.

Thanks!