A method, apparatus and system for globally referenced positioning in a shielded environment includes integrating and correlating information from a UWB receiver, a GPS receiver, and a bent-path GPS receiver adapted to extract a GPS radio frequency wave from a heterodyned GPS signal. In the method, a substrate having a first surface and a second surface on an opposite side of the substrate to the first surface is provided. Polarization-dependent front end units include polarization beam splitters for separating the light into orthogonally polarized sub-beams, and a polarization rotating element, e. The hydrophobic materials include photographic addenda such as color couplers or solid particle dyes. The device may be used in atmospheres containing various harmful gases, and may provide particularly useful improvements in NOx breakthrough times compared to a device containing only the first filter media particles or only the second filter media particles.