The rule of thumb is that MOST of the 9x9's are asbstos, as is most of the associated black mastic....and that MOST of the 12" tiles are not asbestos, as is the associated colored mastic.

You can go to Home Depot (etc) TODAY, and buy asbestos floor tiles, made in Canada.

There are many 9" tiles that are negative, and many 12" tiles that are positive....the sizes are potential indicators of time period, due to styling popular during different time periods...but styles come back, etc.

So - there's no guarantee that that tiles are asbestos containing or not based soley upon appearance.

Polarized Light Microscopy (PLM) and Transmission Electron Microscopy (TEM) are the legally acceptable ways of determining asbestos content in floor tiles and mastic.

You are always allowed to just SAY a material is positive, and treat it as such...but testing is REQUIRED to say a material is negative.

As for what to do about it in a home...there's very little in the way of law, as agencies don't have residential jurisdiction if you are doing it yourself...as soon as you pay someone else though, OSHA has jurisdiction, etc.

Based upon past experiences...people who chip up old flooring get asbestos into the air....but there are no symptoms of exposure for decades...so the one's doing it typically have no idea what they did to themselves or other occupants (Their kids, etc...)

The heat gun methods pretty much never creates much dust.

Creation of dust is the one thing you need to prevent...as that's the ony way the asbestos can hurt you, is if you breath in the invisible fibers.

If you want different appearance/flooring, and the floor is intact, etc......you can put the new one over the old one...the only downsides being potential resale issues, and, issues that can arise if the new one is attached to the old one, rendering removal of the new one (One day...) an asbestos project, etc...