Final answer:
If forced air ventilation is not sufficient to maintain a safe condition in a space, additional measures such as air purifiers or PPE must be used. Addressing the source of the pollution is also important.
Step-by-step explanation:
If the space cannot be maintained in a condition safe to enter by continuous forced air ventilation only, additional measures must be taken to ensure safety. One possible solution is to use air purifiers or air scrubbers, which can help remove pollutants and improve air quality. Another option is to use personal protective equipment (PPE) such as masks or respirators to protect individuals entering the space from harmful substances. Finally, it may be necessary to address the source of the pollution, such as fixing leaks or removing hazardous materials, in order to create a safe environment.