"Indoor air quality is one of the most important variables impacting people's health and well-being and indoor air environments contain a complex mixture of biological contaminants such as bacteria, fungi, viruses, algae, insects and all of their by-products including endotoxins, mycotoxins, volatile organic compounds, etc. These contaminants have been categorized according to whether they are allergenic, infectious, and if they are capable of inducing toxic or inflammatory responses in human beings. Possible sources of biological contamination of indoor air include people, organic dust, various materials stored in the buildings, and the air inflowing from the ventilation and air conditioning systems. Exposure to biological contaminants may result in diseases e.g., infections, allergies or capable of causing toxic or inflammatory reactions in humans. At present, there is a lack of awareness about biological contamination in the indoor environment and their potential sources for the spreading of various infections"-- Provided by publisher.