Eyewash facilities must be provided when:

Eyewash facilities are critically important in workplaces where employees may be exposed to corrosive materials. The primary purpose of these facilities is to provide immediate decontamination to the eyes in the event of exposure to harmful substances. Corrosive materials can cause permanent damage if not rinsed from the eyes promptly; therefore, having eyewash stations readily available is a vital safety measure. This ensures that employees can flush out harmful chemicals quickly, minimizing the potential for injury and facilitating a safer working environment.

The other options do not reflect the essential requirements for eyewash facilities. While medical attention is important, eyewash stations are intended to provide immediate aid, not to eliminate the necessity for professional medical treatment. The mention of a specific duration of use (five minutes) is also irrelevant; the standard practice recommends using eyewash for at least 15 minutes to ensure thorough rinsing. Lastly, the suggestion that keeping eyes closed tightly would enhance the efficacy of an eyewash is misguided; the goal is to flush contaminants away with water, requiring the eyes to be open for effective rinsing. Overall, the focus on corrosive materials underscores the necessity for immediate response measures in hazardous work environments.