Enforcement of a state campaign to crack down on impaired drivers, including impairment from marijuana in the wake of its legalization, begins Monday.

The state Office of Public Safety and Security’s Highway Safety Dvision is providing money to the state police and more than 150 police departments to conduct a zero-tolerance enforcement effort.

Impairment increases exponentially when alcohol and marijuana are combined, the agency said.

The statewide push comes in the absence of a real-time test to measure the level of marijuana in a person’s system. That remains a concern, but participating departments say they are equipped with other tools.

Drug recognition experts, officers trained in advanced roadside impaired driving enforcement and sobriety checkpoints featuring breath alcohol testing mobiles are included in the enforcement effort.

The Highway Safety Division is providing grants for Aug. 14 to Sept. 4, with amounts depending on a community’s population. Worcester got $28,000 for 28 officers to participate, police Sgt. Sean Murtha said. It works out to about 112 four-hour overtime shifts for the 28 officers.

Sgt. Murtha said the department would handle marijuana as it does prescription medicine, heroin and other drugs: Police make a determination based on the totality of the circumstances, including statements and behaviors of the suspected drugged driver and witness accounts.

Worcester has three certified drug recognition experts available to be called out if there are drugged driving arrests, Sgt. Murtha said.

These experts can conduct an in-depth sobriety exam to try to determine what substance, if any, the driver is under the influence of, he said.

There is nothing like the simple as the breath analysis test used for drunken-driving suspects, but there have been successful prosecutions for driving under the influence of drugs, the sergeant said.

Voters throughout the state approved the regulation and taxation of marijuana for adult use in November, but driving while under the influence of marijuana remains illegal.

Jeff Larason, director of highway safety for state public safety and security, said the absence of real-time marijuana testing is one of the big concerns about marijuana legalization. Such testing is not likely to exist for a while, he said.

“What the state has been doing for a number of years, and will be building up, is to train officers, in different forms of training, to be able to detect drug use so that it can be used in court,” he said.

The Drug Recognition Expert program is generally recognized in court as the level of expertise needed to be able to determine if a driver was impaired at the time he was pulled over or involved in an accident, Mr. Larason said.

There are about 130 Drug Recognition Experts on the staffs of police departments around the state, he said.

An Advanced Roadside Impaired Driving evaluation is considered a step beyond standard field sobriety tests.

Officers who have completed these programs are trained to recognize and deal with people who blow a 0 on a Breathalyzer but are clearly impaired, Mr. Larason said.

Southbridge Police Chief Shane D. Woodson, whose department received $2,500, said a drugged driver will often consent to a breath test because he knows that it will register negative for alcohol. But he said the zero reading “gives us more ammunition” when the driver has glassy eyes, is unsteady, appears confused and has speech problems.

“We’ve eliminated alcohol altogether because you just took a Breathalyzer test and you blew a zero, and yet you’re still exhibiting some of those symptoms of being intoxicated on some type of substance, not alcohol.”

Fitchburg police received $3,000 under the program.

Fitchburg Captain Matthew LeMay said getting drivers under the influence of marijuana off the road remains difficult.

“With marijuana it’s more challenging, because it’s new, and the enforcement side of it is fairly new. But officers are going to do the best that they can with the tools that are given to them.”

Fitchburg doesn’t have its own drug recognition expert, but the ability to call one in from elsewhere is “extremely helpful,” the captain said.

“We are looking to send three of our officers to the school, but they don’t offer the schools all of the time, so it’s a challenge,” Capt. LeMay said.

“We’re going to approach it the best that we can,” he said, “based on the staff that we have, and the extra funds. If we make arrests because people are impaired with marijuana, we’ll call a drug recognition expert to do post-arrest testing here at our station for court purposes and move forward from there.”