A MEMS apparatus has a substrate, a cap forming first and second chambers with the base, and movable microstructure within the first and second chambers. To control pressures, the MEMS apparatus also has a first outgas structure within the first chamber. The first outgas structure produces a first pressure within the first chamber, which is isolated from the second chamber, which, like the first chamber, has a second pressure. The first pressure is different from that in the second pressure (e.g., a higher pressure or lower pressure).