LYNN – It comes in a dose roughly the size of a AAA battery, and it is a frontline weapon in the war against opiate drugs that Denny DesRosiers said has saved lives.DesRosiers works for the Healthy Streets Outreach Program where, he said, workers have trained 4,397 people since 2007 in using Naloxone, better known as Narcan. Injected or administered nasally, Narcan reverses overdoses from opiate drug use – principally heroin – buying time for emergency responders to save someone’s life.A Lynn resident, DesRosiers has trained firefighters, police officers and “simple civilians on the street” to use Narcan. He has also saved the life of a woman overdosing in Revere a week after he started working for Healthy Streets.”I gave it to her and, in what seemed like two minutes, she was breathing,” DesRosiers said.Lynn native Jordan Avery is also familiar with Narcan’s ability to save lives. A trained emergency first responder, Avery said he came to the aid of a man attempting to revive a woman last week as she lay in front of the Central Square Dunkin’ Donuts.He used Narcan sprayed into the woman’s nose to help save her life.”She didn’t wake up right away. It took a few seconds and then she came around,” he said.District Attorney Jonathan Blodgett in January, citing State Police statistics, said heroin overdoses killed 145 people in Essex County in 2014. Overdose deaths in Lynn totaled 33 between January and November 2014.Building on a declaration by former Gov. Deval Patrick, Gov. Charlie Baker this year prioritized opiate drug abuse as a top state concern. State health officials launched a pilot project to distribute Narcan in hopes of making it readily available to people trained in stopping overdoses.Healthy Streets is one of 22 programs statewide distributing Narcan and training people to use it.It takes 40 minutes for DesRosiers to train a Narcan carrier and seconds to administer the pocket-size lifesaver.”You pull the yellow tabs off the plastic tube, twist on the atomizer, pull off the purple seal, twist it on and it’s half in one nostril, half in the other,” he said.Avery, 23, said he started carrying Narcan last spring when he was struck by the severity of Massachusetts’ opiate drug problem.”It’s really getting bad,” he said.He currently trains people to provide emergency care and urges his students to be prepared to jump into action.”You have to be ready in the moment – you’ve got to do what you have got to do,” Avery said.State officials do not track actual Narcan use, said Public Health Department spokesman Scott Zoback, adding, “Narcan is in the hands of first responders, advocacy groups, and is available for sale at pharmacies.”DesRosiers said Healthy Streets has documented 932 incidents since 2007 in which Narcan was used in response to an overdose. Information provided by people who helped save a drug user’s life assists Healthy Streets in fine-tuning ways it helps fight addiction. The organization provides testing for HIV, hepatitis C and sexually transmitted diseases in addition to providing Narcan and training people to use it.Not all Narcan interventions save lives, DesRosiers said.”Unfortunately, there were instances in which people passed away. Not every outcome is good,” he said.