A system comprising a breathing headpiece, a hose and a filter cartridge (100, 200, 300) capable of removing contaminants comprising organic vapor from a gas medium, said filter cartridge comprising: a sealed cartridge housing comprising: a gas inlet (110, 210, 310) configured to be in fluid communication with the external environment; filter media; and a gas outlet (140, 240, 340), wherein the gas outlet comprises an outlet port that connects the cartridge housing to a hose to supply filtered gas medium to the breathing headpiece and is configured to be in fluid communication with the user, either directly or indirectly, wherein the filter media comprises a multi-layer construction comprising: a first sorbent layer (120, 220, 320) configured to adsorb the organic vapor from the gas medium; a second sorbent layer (130, 230, 330) directly adjacent to the first sorbent layer and configured to adsorb the organic vapor from the gas medium, wherein the second sorbent layer is closer in proximity to the gas outlet than the first sorbent layer; wherein the first sorbent layer has a higher adsorption capacity and/or higher adsorption rate for the organic vapor than the second sorbent layer; and a sensing element (150, 250, 350) adjacent to the first and second sorbent layers such that an indicating element of the sensing element is located at the interface between the first and second sorbent layers at a location within the filter cartridge such that the sensing element is configured to indicate when an adsorption wavefront containing an organic vapor contaminant reaches the interface between first and the second sorbent layers.. a sealed cartridge housing comprising: a gas inlet (110, 210, 310) configured to be in fluid communication with the external environment; filter media; and a gas outlet (140, 240, 340), wherein the gas outlet comprises an outlet port that connects the cartridge housing to a hose to supply filtered gas medium to the breathing headpiece and is configured to be in fluid communication with the user, either directly or indirectly, wherein the filter media comprises a multi-layer construction comprising: a first sorbent layer (120, 220, 320) configured to adsorb the organic vapor from the gas medium; a second sorbent layer (130, 230, 330) directly adjacent to the first sorbent layer and configured to adsorb the organic vapor from the gas medium, wherein the second sorbent layer is closer in proximity to the gas outlet than the first sorbent layer; wherein the first sorbent layer has a higher adsorption capacity and/or higher adsorption rate for the organic vapor than the second sorbent layer; and a sensing element (150, 250, 350) adjacent to the first and second sorbent layers such that an indicating element of the sensing element is located at the interface between the first and second sorbent layers at a location within the filter cartridge such that the sensing element is configured to indicate when an adsorption wavefront containing an organic vapor contaminant reaches the interface between first and the second sorbent layers.. a gas inlet (110, 210, 310) configured to be in fluid communication with the external environment; filter media; and a gas outlet (140, 240, 340), wherein the gas outlet comprises an outlet port that connects the cartridge housing to a hose to supply filtered gas medium to the breathing headpiece and is configured to be in fluid communication with the user, either directly or indirectly, wherein the filter media comprises a multi-layer construction comprising: a first sorbent layer (120, 220, 320) configured to adsorb the organic vapor from the gas medium; a second sorbent layer (130, 230, 330) directly adjacent to the first sorbent layer and configured to adsorb the organic vapor from the gas medium, wherein the second sorbent layer is closer in proximity to the gas outlet than the first sorbent layer; wherein the first sorbent layer has a higher adsorption capacity and/or higher adsorption rate for the organic vapor than the second sorbent layer; and a sensing element (150, 250, 350) adjacent to the first and second sorbent layers such that an indicating element of the sensing element is located at the interface between the first and second sorbent layers at a location within the filter cartridge such that the sensing element is configured to indicate when an adsorption wavefront containing an organic vapor contaminant reaches the interface between first and the second sorbent layers.. a first sorbent layer (120, 220, 320) configured to adsorb the organic vapor from the gas medium; a second sorbent layer (130, 230, 330) directly adjacent to the first sorbent layer and configured to adsorb the organic vapor from the gas medium, wherein the second sorbent layer is closer in proximity to the gas outlet than the first sorbent layer; wherein the first sorbent layer has a higher adsorption capacity and/or higher adsorption rate for the organic vapor than the second sorbent layer; and a sensing element (150, 250, 350) adjacent to the first and second sorbent layers such that an indicating element of the sensing element is located at the interface between the first and second sorbent layers at a location within the filter cartridge such that the sensing element is configured to indicate when an adsorption wavefront containing an organic vapor contaminant reaches the interface between first and the second sorbent layers..