Which of the following is NOT a type of ventilation system mentioned?

The term "capillary ventilation" is not recognized as a standard type of ventilation system in occupational health and safety practices. Ventilation systems are generally categorized into several well-defined types that are designed to control air quality in various environments, and they include systems that specifically aim to remove contaminants or provide fresh air.

Down draft hoods, local exhaust ventilation, and dilution ventilation are all established methods of controlling air pollutants. Down draft hoods are typically used in laboratory or industrial settings to capture hazardous fumes or particulates before they can affect the worker. Local exhaust ventilation focuses on removing contaminants directly at the source, ensuring that pollutants do not disperse into the general workspace. Additionally, dilution ventilation involves mixing contaminated air with clean air to lower the concentration of pollutants in the work environment. Each of these methods has specific applications and is supported by established safety standards and practices.

Capillary ventilation, however, does not fit into these recognized categories, making it an outlier in the context of ventilation systems. Thus, understanding the context and purpose of established ventilation types helps clarify why one would not include capillary ventilation in a discussion about ventilation systems.