PARC is developing extremely sensitive room-temperature printed gas sensors based on arrays of modified carbon nanotubes (CNTs). The sensors are combined with electronics to form distributed gas sensing networks for applications including natural gas leak detection, equipment failure, industrial safety, and indoor air quality monitoring. The sensing materials comprise CNTs modified with coatings, chemical functionalization, and nanoparticles, to achieve sensitivity to a wide selection of gases including CH₄, NH₃, CO, H₂S, and others. Advanced machine learning techniques allow gas identification and sub-ppm sensitivity. Digital printing of sensor materials on printed electrodes enables low-cost, simple customization of sensor design, and electrode layout. An overview of the project and recent experimental results will be presented.