res·pi·ra·ble 
(rĕspər-ə-bəl, rĭ-spīr-)
(rĕspər-ə-bəl, rĭ-spīr-)adj.
1. Fit for breathing: respirable air.
2. Having characteristics, especially small size, that result in deposition in the lungs after inhalation: respirable particles.
3. Capable of being metabolized by respiration: a respirable substrate.
res′pi·ra·bili·ty n.