Samsung is developing an environmental sensor, according to the Patent Office of South Korea. Looking at the graphics in the document, the sensor most likely will detect the amount of particles along with the change of resistance and will provide data about the air quality. It will be built into smartphones, tablets and smart watches.
Patent application graphics
The environmental sensor will be built into the display without taking actual screen space.
There is no information if such project will ever be made for mass production. After all, the patent application is still just a bunch of documents, explaining how a technology works in theory and also giving the right to the owner to develop it.
Source | Via (in Dutch)