Explain what a "health surveillance" program entails.

A health surveillance program is fundamentally about the systematic monitoring of workers' health to detect occupational illnesses early. This type of program aims to identify any adverse health effects that may arise due to exposure to hazards in the workplace. Regular monitoring can include medical check-ups, screening tests, and health assessments specifically designed to spot early signs of work-related illness or injury.

This proactive approach not only helps in safeguarding employees' wellbeing but also enables organizations to take timely actions, such as modifying exposure limits or improving workplace conditions, based on the health data gathered. It plays a crucial role in occupational health and safety by ensuring that potential health issues are addressed before they develop into more serious conditions.

In contrast, controlling access to hazardous areas focuses more on physical safety measures, while providing first aid services is about immediate medical response to injuries. Implementing physical modifications to the workplace primarily addresses environmental risks rather than individual health monitoring. Therefore, the core of a health surveillance program lies in its systematic and continuous observation of health trends among workers.