Ians, the tape marks the limit of the warm zone. Outside no protection is required.
Nice try!
      How it works is source, then safe buffer zone securely marked, then safe zone outside. Also for any airborne pathogen or gas you need a wind sock so you know which way to evacuate. Played about in hydrogen sulphide environments often enough to know the procedures blindfold.( one good lung full and you get an instant lesson on how to sit on a cloud and twang a harp) The area cordoned off had differing levels of protection inside. The white suits have open cuffs neck,legs and arms.
Also if you were serious you would not have the people all mixed up together as shown and I would expect to see shower units for decontamination of the suits.
I am afraid either the photograph is poorly shot and the personnel improperly briefed or more likely it was staged by a halfwit.