American police have long used breathalyzer equipment to test the blood alcohol level of drivers. Now, with more states legalizing the use of marijuana, similar devices are being developed to measure other drug levels in a person’s system. Unlike alcohol breathalyzers, police have had no devices for measuring marijuana levels during traffic stops. Current methods for identifying drug levels require small amounts of blood, bodily fluids or hair. Such tests can take a long time and only measure recent drug use, not whether a person is currently under the influence. Two companies recently announced they had created marijuana breathalyzer devices and plan to market them to police agencies. University researchers also released details of a device they developed to provide immediate readings for marijuana levels.