Ventilation

Ventilation is used to clear very heavy loads of contaminants in industrial processes such as welding, so it is clear that it can be effective in producing an acceptable working environment even when the air is potentially very contaminated.

Effective ventilation requires an airflow; with fresh outside (‘supply’) air brought into the premises and stale smoky air expelled (‘extract’). If rooms only have extraction the fans will be ineffective as they require fresh air to replace the air that is extracted. This can either be done through ‘natural’ ventilation (open windows or doors) or through ‘mechanical ventilation’, which usually requires fans in windows, walls or ducts to move the air. Both can be highly effective at cutting the amount of ETS in a room – but probably only mechanical ventilation can be relied on throughout the year as windows tend to get closed in cooler weather.

Almost all fans have a published airflow rate or ‘duty’. This makes it easy to calculate how many fans are needed in the space when specifying ventilation.

Some examples of mechanical ventilation effectiveness can be found at ventilation test results. These show ventilation consistently reducing the amount of ETS in the air by 80-90% and keeping the carbon dioxide, carbon monoxide and particulate well within workplace exposure limits even at the busiest times on the busiest evenings.