MAYOR NUTTER has called Philadelphia International Airport "the economic engine for all of Southeastern Pennsylvania." Unfortunately, that engine is maintained, in part, by thousands of workers who are forced to rely on charity, public-assistance programs, or the kindness of friends and family to survive.

A survey conducted by the National Employment Law Project noted that some 2,000 airport workers employed by subcontractors earn a mean hourly wage of $7.85 - which equals an annual income below the poverty line for a family of four.

Incredibly, one in five of those surveyed worker s- skycaps, baggage handlers, security workers, cabin cleaners, wheelchair assistants - had to forego a meal in the past year because they couldn't afford to eat. Nearly 75 percent had trouble paying their bills. And almost a third missed work because they couldn't afford transportation to the airport!

There's something deeply unseemly about a workforce at one of the city's most lucrative assets earning such low wages - especially when Philadelphia has the highest poverty rate of any of the nation's 10 biggest cities, and a mayor who launched an antipoverty initiative last summer.

Their employers have been able to pay poverty wages because the Nutter administration has interpreted the city's living-wage standard as applicable only to employees of companies with direct contracts with the city - not employees of the subcontractors they hire in turn. That standard mandates a wage floor of 50 percent of the federal minimum wage - or $10.88 at the moment.

There are untold numbers of subcontracted workers in the city, then, who earn less than that standard, sometimes much less because their pay is determined by low-bid contractors.

Councilman Wilson Goode, who has long championed the plight of ill-paid workers and was responsible for the original passage of the living-wage standard in 2005, hopes that a referendum on the May primary ballot will override the city's interpretation. Voters will be asked to change the city charter and give Council the right to mandate living-wage pay for subcontracted workers as well as contracted workers. Presumably, the question will be approved.

In light of that, the administration is now including a living-wage provision for all workers - including subcontracted workers - in the requests for proposal it's sending out to airport concessionaires, whose contracts with the city expire next June. And officials are trying to determine how the pay mandate can be enforced with the airlines when leases come up for renewal, since they are tenants rather than contractors.

Things seem to be slowly moving in the right direction.

You can thank Wilson Goode for that, along with faith and community and union leaders who've rallied around the airport workers' cause here.

Last month, voters in SeaTac, a suburb of Seattle, Washington, passed a ballot measure that raised the minimum wage to $15 for thousands of airport and hotel workers there. Philadelphia airport workers staged a celebratory rally at City Hall, to pressure the administration and encourage voters to approve the referendum.

As well voters should. The double standard of pay is illogical and immoral. No one who works directly or indirectly for the city should ever have to go hungry.