Adding more security measures at U.S. airports might not be worth the cost, according to a new report, which notes that it might even make sense to relax some of the existing security tactics.

John Mueller, a professor of political science at Ohio State University, and Mark G. Stewart, a civil engineering professor at the University of Newcastle in Australia, conclude that airports are not good targets for terrorists, and the odds of being killed in an airport attack are extremely long, LA Times reports. The study, Cost-benefit analysis of airport security: Are airports too safe?, relied on cost and risk reduction numbers for LAX, but were calculated before the Nov. 1 shooting that left Transportation Security Administration agent Gerardo Hernandez dead. However, Mueller says, the shooting did not change the cost analysis.

The study looked at several potential threats, including a gunman, a suitcase bomb, a truck bomb and a bomb strapped to a person. The professors also examined the cost and effectiveness of such security measures as adding more bomb-sniffing dogs, installing permanent vehicle search checkpoints and shatterproof glass and blast deflection walls at airports. The study concluded that the cost of such measures would not be justified, as they would not completely eliminate the threat.

“Moreover, if the analysis suggests that enhancement of airport security is highly questionable, it may well be time to consider if many of the security arrangements already in place to protect airports are excessive,” the report states.