Air sampling devices placed around Philly for papal visit

PHILADELPHIA (WPVI) -- As workers continue setting the stage for the papal visit, security officials are also working hard to make sure all is ready for this weekend.

But their work is happening behind the scenes.

One sign of their efforts: Dozens of air sampling devices are popping up on streets around the periphery of the Ben Franklin Parkway and Independence Mall.

They'll be sniffing for chemicals and radiation as the crowds pass by.

Concrete Jersey barriers are also in place, ready to close off access when the vehicle security zone goes into effect.

Signs are already posted directing pedestrians to the security checkpoints. Other signs spell out what they can't bring with them.

Some are calling it overkill, while others say it's today's reality.

"With all the stuff that's going on since the marathon, you have to be protected. It might be overkill, but you have to do it to make people safe. There's going to be a lot of people here," said Anthony Davis of Lansdowne, Pa.

Meanwhile, the feverish work continues to get the staging ready for the pope's arrival. There are thousands of details to take care of, and none of them too small.

Joe Jardine is one of hundreds of men and women working to get the job done. There are long hours with little rest, but he doesn't mind.

"It's like a time in history. The last time the pope was here was the 70's. It's a time in history and I can say I did it," Joe told us.

Elsewhere The Streets Department was hanging covers on traffic lights, hand-painted by school children.

And the pilgrims are coming already. Crowds of them walked the Parkway just to get close enough to take a picture of the stage and altar.

That includes Boris Altshatater, who's Jewish. He'll be here this weekend.

"Yes, I have a ticket. I don't know if I'll be able to see him, but I want to see him, yeah," Boris said.

Upwards of one million people are expected in Philadelphia over the weekend.