Explanation
Company S could take various steps, which are as follows:

The occupational hazard can be prohibited by implementing safety procedures at the workplace. So, it is required to implement appropriate safety programs and frequent examination of the working conditions at towers.
The employees can be subjected to operations and equipment training for the subcontracted employees so that they adhere to the stated guidelines. The implemented safety programs should be analyzed from time to time for maintaining their effectiveness.
Sample Response
Company S could also take the following safety steps:

Regular examination and inspection of working conditions at towers to ensure safety and security
Operations and equipment training to subcontracted employees to ensure Organization O's safety requirements