Currently limited information/knowledge is available about the occurrence, sources and distribution of flame retardants (FRs) in the potable water, air and dust as well as their associated health risk to the exposed human population. This is the first study designed to probe selected flame retardants (FRs) in the indoor and outdoor air and dust as well as potable water samples at different altitudinal zones (industrial, rural and background) of Pakistan with special emphasis upon their occurrence, distribution and associated health risk diagnosis. Therefore, the selected FRs viz., Polybrominated diphenylethers (PBDEs), Dechlorane plus (DP), Novel brominated flame retardants (NBFRs) and Organophosphate flame retardants (OPFRs)) in a total of 38 air (indoor and outdoor), 82 dust (indoor and outdoor) and 39 potable water samples were collected from different altitudinal zones. The targeted FRs were analyzed by Gas chromatograph Agilent 7890A coupled to mass spectrometer (5973C MSD) in electron capture negative ionization (ECNI) and GC/MS-MS Agilent 7000A triple Quad operating in Selective ion mode (SIM). Results for the targeted FRs in the air (indoor and outdoor) samples collected from different altitudinal zones showed the trends as: ΣNBFRs > ΣPBDEs > ΣDP, While for the dust (indoor and outdoor) samples were ranked: ΣOPFRs > ΣNBFRs > ΣPBDEs > ΣDP. Significant correlation among FRs in the indoor and outdoor air at different altitudinal zones suggested similar source origin of FRs used in different consumer goods. Significant correlation in the FRs levels between the indoor and outdoor dust suggested the potential intermixing of these compounds between different environmental matrices. Similarly, Principal component analysis (PCA)/Multiple linear regression (MLR) predicted the percent contribution of FRs from different consumer products in the indoor and outdoor dust of industrial, rural and background zones to trace their source origin. Furthermore, air mass trajectories for air samples revealed that movement of air over industrial area sources influenced concentrations of FRs at rural sites. While, for dust samples, the forward and backward air mass trajectories showed that the FRs detected in the background zones reveal the dust-bound FRs suspended in the air might be shifted from different warmer zones or consumers products available/used in the same zones. Elevated concentrations of FRs in the potable water samples were revealed in the industrial zones followed by rural and background zones, while the decreasing trends for FRs in the potable water samples highlighted were: ΣOPFRs > ΣPBDEs > ΣNBFRs > ΣDP due to the much higher water solubility for OPFRs as compared to the other BFRs. Among the analyzed FRs, Tris-(2-chloroisopropyl)-phosphate (ΣTCPP), anti-DP, BDE-47 and 1,2- bis(pentabromodiphenyl)ethane (DBDPE) were the dominant compounds in three selected zones. Principal component analysis (PCA) revealed that most of the FRs are associated with the industrial zones. It is suggested that FRs might be leached out from wastewater bodies and subsequently mixed with nearby potable water facilities. FRs may also spill out from the aluminum or plastic pipes and tanks most commonly used for potable water storage in Pakistan. xv The FRs concentrations, estimated daily intake (EDI) and the hazard quotient (HQ) in potable water, air and dust samples were recorded higher in toddlers as compared to adults. Moreover, the indoor air and dust samples showed higher FRs levels, EDI and HQ than outdoor air and dust samples. It was found that in air, dust and potable water samples an elevated FRs concentrations, EDI and HQ were recorded in the industrial zones followed by rural and background zones. HQs for FRs in the Children/toddlers and adults via potable water consumption and indoor and outdoor dust were <1 highlighting no risk to the vulnerable population. While on the other hand, the HQ values >1 in toddlers and adults population warrants a health risk for BDE-47 and -99 in most of the indoor and outdoor air samples at the industrial zones; while for BDE-47 in the toddlers at indoor and outdoor air samples in some sites at the rural zones of Gujrat and Gujranwala, Pakistan. The results of this study will provide a baseline record for FRs (PBDEs, DP, NBFRs and OPFRs) concentrations in the indoor and outdoor air, dust and potable water at different altitudinal zones in Pakistan. Strict implementations in regard of FRs associated products are needed to minimize the future health concerns through FRs exposure. Alternative products should be introduced to reduce the hazards from FRs. Furthermore, detailed studies are required to assess the long range transport of FRs and modeling approaches for better understanding of their distribution in different environmental compartments. Key words: Flame retardants, Air, Dust, Potable water, Exposure pathways, Pakistan