Herein, we present an overview of recent progress on the development of different types of porous 1-D photonic crystal coatings which are optically responsive to gas pressure changes in the environment. Modification of the surrounding vapor pressure gives rise to adsorption and condensation phenomena within the porous networks of the photonic crystal building blocks, varying their refractive index and hence their optical features. This effect can be put into practice to precisely detect and monitor changes in the ambient through the spectral shift of either the photonic bandgap of the structure or of some other optical features. Our results demonstrate the potential of these optical coatings as new materials for gas sensing devices.