199 Estimation of bioaerosol in indoor environment in the university library of Delhi 1 2 2 2 2, Bipasha Ghosh, Himanshu Lal, Rajesh Kushwaha, Naba Hazarika, Arun Srivastava * 2 and Vinod Kumar Jain 1 Indira Gandhi Academy of Environmental Education Research and Ecoplanning Jiwaji University Gwalior 474011, India 2 School of Environmental Sciences Jawaharlal Nehru University New Delhi 110067, India Key Words: Bioaerosol, library environment, source identification, allergic fungi, indoor air quality *Corresponding author Email: srivastava02@hotmail.com ABSTRACT INTRODUCTION Ambient levels of viable bioaerosol (fungi, Gram positive and negative bacteria) were measured in Central Library, Jawaharlal Nehru University, New Delhi during July 2011 to October 2012. Study was done at five indoor sites [basement, reading hall, 3rd, 4th and 5th floors] and one outdoor. Air samples were drawn into standard petri dishes using Buck Bio-culture pump at a flow rate of 40 L -1 min for 1 min. This study reveals interesting relationship between the concentration of fungal spores and bacteria in relation to both environmental and human factor. Most observed fungal species detected in the samples were Rhizopus oryzae, Aspergillus nidulans and Aspergillus flavus. Specific bacterial identification was not possible but Gram staining followed by microscopic analysis helped in deriving the different shapes of bacteria collected. Bacillus and Coccus were found maximally. Indoor/Outdoor ratio above 1 for fungal spores signified higher source in the indoor environment at different sections. In indoor environment highest fungal concentration was found in Basement (3140 -3 -3 colony-forming units (CFU) m ) while lowest in 3rd floor (2560 CFU m ). In case of bacterial concentration both Gram negative and positive bacteria were found maximum in the Reading Hall -3 -3 (792 and 696 CFU m , respectively) while lowest in 3rd floor (475 and 437 CFU m , respectively). Higher bacterial counts were primarily attributed to the number of library occupants. High concen- tration may be due to larger rate of shedding of human skin cells, microbes released from respiratory tract and transport of microbes from floor surfaces on suspended particles. . As a generic class of airborne pollutants, particu- late matter usually associated with compounds of bio- logical origin is often termed as “Bioaerosol”. This definition includes all airborne microorganisms re- gardless of viability or ability to be recovered by cul- ture; it comprises whole microorganisms as well as fractions, biopolymers and products from all varieties of living things [1]. Bioaerosols may consist of patho- genic or non-pathogenic, live or dead fungi and bacte- ria, bacterial endotoxins, mycotoxins, peptidoglycans, â (1,3)-glucans, viruses, high molecular weight aller- gens, pollens, etc. [2]. . Bioaerosols may originate from almost any natural or man-made surface and each source may give rise to an entirely unique assemblage of air microbes. Differ- ent environments that are mainly bioaerosol sensitive are animal housing [3], composting and dumping sites [4], ceilings and walls of indoor surfaces [5], saw mills [6], and food processing and manufacturing plants [7]. Poor indoor air quality has been shown to cause several health hazards. In many indoor environments airborne bacteria, fungi and their fragments may fall into respi- rable size range that can penetrate deep into human lungs (< 10 μm) [8,9]. The presence of undesirable bioaerosols is often associated with sick building syndrome (SBS) and building related illnesses [10]. Sources include furnishings and building materi- Sustain. Environ. Res., 23(3), 199-207 (2013)