WASHINGTON — Not long ago, the families of Fairfax (Va.) Presbyterian Church spent thousands of dollars to fly their teens to Mexico for eight days of doing good. They helped build homes and refurbish churches as part of an army of more than 1 million mostly Christians who annually go on short-term international mission trips to work and evangelize in poverty-stricken lands.

Yet even as those trips have increased in popularity, they have come under increased scrutiny. A growing body of research questions the value of the trips abroad, which are supposed to bring hope and Christianity to the needy of the world, while offering American participants an opportunity to work in disadvantaged communities, develop relationships and charge up their faith.

Critics scornfully call such trips "religious tourism" undertaken by "vacationaries." Some blunders include a wall built on the children's soccer field at an orphanage in Brazil that had to be torn down after the visitors left. In Mexico, a church was painted six times during one summer by six different groups. In Ecuador, a church was built but never used because the community said it was not needed.

PROJECTS REVAMPED

To make missionary work more meaningful, some churches are taking a different approach. In response to the criticism, a growing number of churches and agencies that put together short-term trips are revamping their programs and establishing new standards.

For the past four years, for example, the Fairfax Presbyterian youths have stayed closer to home, in places such as Welch, West Va.; Lansing, Mich., and Philadelphia. Last week, a team of 44 were in St. Petersburg, Fla., to clean and paint low-income homes, assist the homeless and volunteer at a free health clinic.

Senior Pastor Henry G. Brinton said the church realized that the teens could do just as much good working close by as far away.

"It became too hard to justify the expense of flying the kids overseas," Brinton said. "If you're going to paint a church, you can do that in Florida as easily as you can in Mexico."

Fairfax Community Church is repositioning its mission trips "to get away from the vacation-with-a-purpose, large groups going somewhere to build something" focus, said Alan MacDonald, the church's pastor of global engagement.

The church is sending out smaller teams of experts to work on projects with partner churches. For example, it is sending information technology professionals who are fluent in Spanish to a church in the Dominican Republic to train members in computer skills so they can get better jobs, MacDonald said.

LONG MISSIONS DECLINE

Despite the concerns with trips abroad, their popularity is soaring. Some groups go as far away as China, Thailand and Russia. From a few hundred in the 1960s, the trips have proliferated in recent years. A Princeton University study found that 1.6 million people took short-term mission trips — an average of eight days — in 2005. Estimates of the money spent on these trips is upward of $2.4 billion a year. Vacation destinations are especially popular: Recent research has found that the Bahamas receives one short-term missionary for every 15 residents.

At the same time, the number of long-term American missionaries, who go abroad from several years to a lifetime, has fallen, according to a Wheaton College study done last year.

The short-term mission trip is a "huge phenomenon that seems to be gaining in momentum rather than waning," said David Livermore, executive director of the Global Learning Center at Grand Rapids Theological Seminary, who studies the trend.

Participants care for orphans, hold Bible classes, evangelize, paint homes and churches, and help AIDS patients, among other tasks.