i believe Bob Wood from Mr. Radon has done this before with a stage smoke machine on a very large slab. I am pretty sure its an item that can be rented (although not exactly for its intended purpose). Just look for the smoke where there may be any leaks.............

Like Brooks I was going to recommend a stage smoke machine. I have used them in the past for haz mat containment confirmation. They pump out lots of smoke. Lots of models available on amazon for under $100

To manage the pressure try an inverted radon fan and add a router speed controller to dial it down to exactly the output you need about $30. You can even get inline duct fans with built in speed control. Here is an example of both on amazon just scroll down to see some options. I suspect just about any model will do for your needs https://www.amazon.ca/Harbor-Freight-Tools-43060-Control/dp/B002MLE01A

I have a modified vacuum hose I use for sub slab diagnostics. It has T with a ball valve to bypass the suction. I use it to dial down the pressure to better simulate a fan's suction level. [img]http://c:\users\jim\googledrive\radonguys\floorplans\img_2456.jpg[/img]

We would routinely do smoke testing when commissioning fume hood and commercial kitchen hoods.
A smoke generator with long duration smoke oil, is best, today, I would use an Fantech RN4 variable volume fan- with a membrane, you have to be very careful, not to over pressurize it and blow the seals! Ballast your membrane first.
We typically, depressurize our membranes and use smoke on the seams and foundation connection- much less likely to blow a seals.

if you are doing a partial slab you simply sandbag or water bag (Pool Bags) the open side, my commercial smoke machine (stage smoke) by it a music store, only seems to do about 1000 to 1500 sq ft at a time. on my next project i will use a corn oil smoker as apparently it will do 20,000 sq ft or more. apparently Corn oil can show up as a VOC in later testing so you need to be cautious.

Not to be negative about the radon testing which I think is great, but I am going to bet this requirement is about putting another "bump in the road" to try and limit Airbnb and VRBO rentals than it is about radon testing.