JKAU: Met., Env. & Arid Land Agric. Sci., Vol. 26 No. 2, pp: 83 - 91 (1437 A.H./2016 A.D.) DOI: 10.4197/Met. 26-2.9 83 Bacterial and Chemical Contamination Associated Carpet Dust in the Holy Mosque, Makkah Al-Mukarramah Bassam Husain Mashat Department of Environmental and Health Research, the Custodian of the Two Holy Mosques Institute for Hajj Research, Umm Al-Qura University, Makkah Al-Mukarramah, P.O. 6287, Saudi Arabia Abstract. Carpets are widely used as surface covering in the holy mosque (Almasjed Alharam) settings, and they are prone to contamination with infectious agents and chemical components. This study aims to evaluate the concentrations of bacteria and chemical pollutants associated carpet dust in the holy mosque, as well as bacterial concentrations in the air state. The dust samples were collected from eighty carpets during month of Ramadan 2011, using a cord portable vacuum cleaner. Airborne bacteria were collected using Airport MD8 gelatin filter sampler. Bacterial concentrations varied depending on location of carpets inside the mosque, with no significant differences between locations (P≥0.05). The highest mean bacterial concentrations associated dust (256.42x10 6 CFU/m 2 ) and in the air state (1.12x10 5 CFU/m 3 ) were found at the ground floor of 1st expansion location. The highest re-suspension factor (RF) was found at the ground floor of 1st expansion, and the lowest at ground floor of 2nd expansion. Bacillus (25%), Pseudomonas (13%) and Micrococcus (12%) were the dominated bacterial genera. Chloride and ammonium concentrations associated dust were higher at the basement and the ground floor locations. The results did not indicate the presence of any apparent seriousness of the current situation of the carpets in the holy mosque. The data can be treated as a first step in determining the acceptable levels for microorganisms associated carpets in the common indoor environments. Keywords: the holy mosque, carpet, dust, bacteria, chemical components, risk assessment. Introduction Indoor environment is a unique and is characterized by its own sources. The holy mosque is furnished with the finest carpets, and their number is ~30,000 with various sizes. The carpet is considered a good environment for the growth of microorganisms, if appropriate temperature and humidity are available. The carpet works on absorption and book dust. Simply by walking across a floor, carpet or other flooring materials, microbes can become airborne, which can cause non-infectious airway diseases, allergies, asthma, or serious infectious (Miller and Colemans, 2015). Studies have demonstrated that, in addition to particles suspended in outdoor air, material resuspended from surfaces, as a result of human activities, is an important source of indoor airborne particles. Relationships have been found between indoor airborne microbial contents and those-associated carpets (Bholah and Subratty, 2002; Gehring, et al, 2002, Ferro, et al., 2004; Bouillard, et al, 2005). Carpets and sofas represented a huge reservoir of mites, and allergens (Custovic, et al., 2002),