Modern airports are a potpourri of indoor and outdoor spaces serving commercial and public demands much like small cities. These include: administration; ticketing and baggage handling; lounges and waiting areas; hotels, restaurants, and shops; air traffic control; surface transportation; and aircraft maintenance. These facilities experience environmental challenges from a variety of volatile, particulate, and microbial air contaminants arising from natural and human sources. These contaminants affect comfort and health aspects of indoor air environments. They include general pollutants (smoke, dust, pollen, odors), specific chemicals (unburned hydrocarbons, carbon monoxide), and microbials (bacteria, molds).
The objectives for environmental management of indoor air systems at airports are multiple: minimizing pollutant sources, providing good air handling, and improving Indoor Air Quality (IAQ). Treating air contaminants depends upon the nature of the contaminants, relative concentrations, technical approaches used, and results to be achieved. Technologies involve filtration, adsorption, and electronic processes. Electronic devices, including bipolar air ionizers, electrostatic precipitators, and ozone generators, are functionally related, but have distinct differences in their modes of operation. Bipolar air ionization involves creation of clusters of negative and positive ions by applying electrical energy to air molecules without heating the bulk gas. Reactive species are created that oxidize volatile organic compounds (VOCs) and agglomerate fine particulate matter (PMx).
Demands for more complete treatment of indoor air environments has led to the development of practical engineered systems based upon bipolar air ionization. Air ionization units are tailored to particular facilities depending upon sources and strengths of VOCs and PMx. Air ionization modules are fitted directly into central air handling units to treat entire airflows to meet challenges from external sources. Modules also can be fitted into existing ductwork immediately downstream of central HVAC systems. Freestanding devices can also be placed in individual room spaces to meet immediate demands from internal sources.
Field applications of bipolar air ionization systems require optimization of up to eight process variables of the physical air handling system and the air quality demand. The central process control unit is programmed for fixed situation design parameters (ion level, power capacity, and airflow area), and for monitored demand parameters (airflow, humidity, outside and return air quality, and ozone). Case histories, including ticketing and baggage handling facilities at a major international airport, several FAA control towers, and a number of passenger lounges, will be discussed in terms of process design, unit performance, and IAQ evaluation.