Introduction

The best protection against airborne hazardous materials is high efficiency filtration (U.S. Army, 2001). However, if the efficiency of the supply air filtration is improved with solutions based on old technology, large and expensive modifications in the ventilation systems are needed.

In order to protect buildings and their occupants from airborne hazards Lifa Air has developed in co-operation with VTT Technical Research Centre of Finland advanced low flow resistance, high efficiency LIFA supply air filters which are capable for removing both particulate and gaseous contaminants from the supply air, without extensive modifications.

Of particular concern are occupants in buildings equipped with mechanical heating, ventilating, and air conditioning (HVAC) systems. These systems can become an entry point and a distribution system for an intentional release of toxic chemicals or biological aerosols (fine particles) near air intakes or inside buildings. Once contaminated air enters a building, the ventilation system can transport it rapidly to various parts of the building with serious consequences.

Most strategies for protecting people from airborne hazards require a means of detection - determining that a hazard exists. Although effective and inexpensive devices are widely available to detect, for example, smoke and carbon monoxide, there are no detectors that can rapidly alert occupants to a broad range of chemical and biological hazards.

The possible control strategies for indoor air contaminants include more efficient supply air filtration for buildings with mechanical ventilation or use of high efficiency air cleaners. However, the removal of gaseous contaminants requires gas filters, which are not commonly used in standard air handling units. Moreover, the removal of fine particles from the supply air requires efficient HEPA-grade filtration system. Existing ventilation systems seldom have the space or available static pressure for high efficiency filters. The efficient removal of both fine particles and gaseous contaminants therefore has not been feasible with the present technology. On the other hand, high efficiency air cleaners require floor area, they are noisy and they usually do not have efficient filtration system for gaseous contaminants. Most importantly, they rather dilute contaminants to lower level than prevent the contaminants from entering into the occupied space.

Lifa Supply air filters
The new Lifa 3G Filters filters have been developed to remove harmful airborne contaminants efficiently. Moreover, Lifa High Security filters have been developed specifically against biological or chemical agents.

The new technology combines an electrostatically charged filter with both a particle charging section and a gas filter made of activated carbon media. The pressure drop of such a unit is low, permitting installation without the need for expensive changes in the existing ventilation system i.e. the building infrastructure.

The primary application of the Lifa filter is buildings with mechanical ventilation: offices, public buildings, and manufacturing facilities. In addition to removing outdoor pollutants, the Lifa filter technology is effective against contaminants that are generated indoors and dispersed due to air re-circulation. The filters are intended for installation in ductwork near the air terminal device or diffuser in each room that needs safe and healthy indoor air quality. There are also mobile units for hospital and other emergency purposes.

Lifa TJ 3G Filter
Lifa TJ 3G Filter is developed mainly for airborne contaminants typical in urban environments. It is designed is to prevent contaminants such as fine particles, volatile organic compounds (VOCs), ozone and odours from entering room air and to maintain healthy indoor air quality.

Lifa High Security Filter
The Lifa High Security Filter system is specifically designed to provide protection against both biological and chemical agents. Equipped with the Nanoelectric UV light it is the only scientifically tested and proven filter solution to be (killing) effective against any airborne virus or bacteria, also sizes below 0,3 microns, which is the current, and insufficient, industry standard.