Air filtration and indoor air quality

Demands for better indoor air quality are increasing, since we spend most of our time indoors and we are more and more aware of indoor air pollution. Field studies in different parts of the world have documented that high percentage of occupants in many offices and buildings find the indoor air quality (IAQ) unacceptable and suffer from Sick Building Syndrome (SBS) symptoms (e.g. respiratory, headache, fatigue, etc.). In addition, prevalence of asthma and other respiratory and allergic diseases have increased during the past decades. The effect is most likely related to the environment. Without decent ventilation and air cleaning/air filtration, high indoor air quality cannot be accomplished. The need for effective air filtration has increased with increasing evidence on the hazardous effects of fine particles. Moreover, the air contains gaseous pollutants, removal of which requires various air cleaning techniques. Supply air filter is one of the key components in the ventilation system. Studies have shown that used ventilation filters themselves can be a significant source of indoor air pollution with consequent impact on perceived air quality, sick building syndrome symptoms and performance. Usually, increasing the ventilation rate improves the air quality, however in the case of used ventilation filters the benefits from increasing the airflow are smaller than usual. Moreover, the ever-increasing pressure drop of bag filters tends to raise energy costs of ventilation systems. These contradictions should motivate manufacturers and researchers to develop new efficient filtration techniques and/or improve the existing ones. Development of low polluting filtration techniques, which are at the same time easy and inexpensive to maintain is the way forward in the future.