Air Cleaning Devices for Buildings (with Central Air-Conditioning System)
For buildings with central air conditioning systems, air cleaning devices can be fitted so that the particulate level in the indoor air can be kept within acceptable levels during a prolonged smoke haze period. The devices include electrostatic precipitators and media filters.
Electrostatic precipitators operate by electrically charging dust particles as they pass a set of electrodes. The charged particles are subsequently collected by charged collector plates (with an opposite charge) downstream of the charging electrodes. They have minimal effect on airflow.
Media Filters are mats of fine fibres oriented perpendicular to the direction of airflow. Particulates are intercepted and trapped in the fibres. They are available in a wide range of capture efficiencies. For smoke haze, filters manufactured for more efficient removal of fine particulate should be used. The conventional medium to high efficiency media filters that can trap fine particulate are typically dense and may hinder air flow if the fans are not designed to match them. There is another type of medium efficiency filter that is less dense and therefore exerts a lower resistance to air flow. This type of filter contains electrostatically charged fibres that attract and retain fine particles.
The capital and operating costs vary depending on the particular type of air cleaning devices selected and the design of the air-conditioning system. Based on NEA's assessment, the overall annual cost range from $2,000 to $10,000 for a floor area of 1,300 sq.m. The costs are for an assumed haze period of three months per year. The actual costs of the options will need to be ascertained with system suppliers.
List of Suppliers of Air Cleaning Devices
Information from US-EPA webpage on Residential Air Cleaning Devices
Information from American Lung Assocation webpage on Air Indoor Quality