Airborne particle chart from American Society of Industrial Hygenists
Click for larger view.
The way in which to read this chart is to first note the particle sizes along the top of the table, they range from 100 microns on the left to 0.001 microns on the right.
Then choose in the pollutant you would like information about, for our purposes we look at tobacco smoke.
Note that the particle size range for tobacco smoke is 4 - 0.01 micron range, with 90% of tobacco smoke particles ranging from 1 - 0.01 microns.
Therefore the misleading pro-smoking ban AQ test method of measuring PM 2.5 (micron) particles doesn't even take into account tobacco smoke particles.
Update: OSHA workplace standards regulate air quality in the workplace, and testing proves that secondhand smoke does not violate OSHA standards, more here: