Control of ventilation intakes during peak pollution periods

For pollutant sources such as urban road traffic, whose concentration fluctuates with the time of day, reducing the flow of external air or closing ventilation intakes during peak periods of high external pollutant concentrations, e.g during rush hours, for up to an hour may be an option. Air intakes located on a less polluted side of the building may then be used for fresh air, or air may be fully re-circulated within the building. Alternatively, the building may be used as a "fresh air" reservoir to supply air during these short periods. The use of atria as a source of "fresh air" for this purpose may be an option.