A positive school environment is more likely to deter students from smoking marijuana rather than the usual drug tests, a new study claims.

The study reported in the Journal of Studies on Alcohol and Drugs interviewed nearly 361 students and determined that those studying in positive environments were 20 percent less likely to try marijuana and 15 percent less likely to smoke cigarettes.

Nearly 20 percent of the U.S. high school students undergo drug testing. But this test is randomly done on students. A lot of controversy surrounds these policies mainly because not much evidence is available on the efficacy of such testing.

On questioning 361 students on the policy existing in their school, it was found that one third of the schools followed a drug testing policy. Also, these students were as much likely as other students to pick up cigarettes, marijuana and alcohol.

"Even though drug testing sounds good, based on the science, it's not working," Daniel Romer, Ph.D., of the University of Pennsylvania Annenberg Public Policy Center in Philadelphia, said in a statement. "The policies might convince kids to lay off the drug their school is testing for-which is most commonly marijuana. But even if that's true, students in school sports and clubs are actually not the ones at greatest risk of developing drug problems. So as a prevention effort, school drug testing is kind of wrong-headed."

The study found that a positive school environment was more effective. A positive climate was considered when the kids knew clear rules existed and students and teachers treated each other with respect.

After spending a year in a positive school environment the students were about 20 percent less likely to take to marijuana or smoking.

But the positive environment did not help the students from avoiding alcohol, as in the second interview nearly two third of the students admitted to have tried alcohol, irrespective of the school environment or drug testing policies.

"This may be because drinking is so "normative," even though it's illegal before age 21. The whole culture uses alcohol," Romer said. "And you're fighting something that has widespread marketing behind it."