Lifespan attributes specify how long nParticles remain in your simulation before they disappear or die. nParticle lifespan is measured in seconds, beginning in the start frame of the simulation for static nParticles, and at the point of emission for emitted nParticles. Lifespan can be used as an input attribute for nParticleShape node per-particle ramps such as Radius Scale, Mass Scale, and Color. Using lifespan attributes in this way allows nParticle attributes to be mapped and animated according to the nParticle’s age. nParticle Lifespan attributes are inherited from Maya classic particles, and therefore are set in the same way.
The Particle Size attributes set particle radius. You can use the Radius Scale ramp to map radius on a per-particle basis using nParticle attributes, such as Lifespan, Color, and Mass, as the ramp’s input values.