The safe amount of exposure is reduced by a factor of 2 for every exchange rate (3 dB for NIOSH standard or 5 dB for OSHA standard) increase in SPL. For example, the safe daily exposure amount at 85 dB (90 dB for OSHA) is 8 hours, while the safe exposure at 94 dB(A) (nightclub level) is only 1 hour. Noise trauma can also cause a reversible hearing loss, called a temporary threshold shift. This typically occurs in individuals who are exposed to gunfire or firecrackers, and hear ringing in their ears after the event (tinnitus).