OSHA’s Color Coding System for Cartridges

Green filters protect you from ammonia gases.
White filters protect you from acid gases.
Black filters protect you from organic vapors like solvents in paint and gasoline.
Blue filters provide protection against carbon monoxide.
Yellow filters protect against acid gases and organic vapors.
Teal filters protect you from any particulates free of oil (N95, N99, or N100).
Orange filters protect you from any particulates (P95, P99, R95, R99, or R100).
Purple filters protect you from any particulates (P100).

New respirators may or may not come with the appropriate cartridges. Check before buying and ensure you get the right type of cartridge for the job.