Some 10,000 janitors, airline service workers and other employees of firms hired by the city are making more money, thanks to an ordinance boosting minimum pay while causing a slight decline in jobs, according to a new study.

The five-year joint study by researchers at the University of California, Los Angeles; University of California, Riverside; and Los Angeles Alliance for a New Economy tracked workers and employers covered under LA's living wage ordinance, which went into effect in 1997.

The number of workers who saw their pay rise in LA because of the ordinance was surpassed only by workers in New York and San Francisco, researchers said Wednesday.

Some 60 percent of the jobs covered by boosted wage requirement were at Los Angeles International or Ontario airports, researchers said.

In all, the number of workers who benefited amounted to roughly 2 percent of the low-wage work force in Los Angeles, said David Fairris, a professor of economics at UC Riverside who co-authored the study.

The living wage law requires companies doing business with the city to pay workers a wage above federal minimums. Currently, employers who fall under its requirements must pay workers either $10.03 per hour, or $8.78 per hour plus a $1.25 per hour contribution to help pay for workers' health care benefits.

Federal minimum wage is $5.15 per hour. California's minimum wage is $6.75 per hour.

Critics of such ordinances argue that they help few workers and cause companies to hire fewer people, but the study found job losses amounted to 1 percent.

Employers also managed to recoup some of the cost of higher wages by cutting some fringe benefits and overtime, hiring more trained workers and benefiting from reductions in employee turnover and absenteeism, researchers said.