There are basically three types of injuries.

The first and most common one is poor lifting techniques. TSA is trying to remedy this by educating screeners on proper lifting techniques, but it's all too easy to forget during the rush of a busy period. Screeners should lift bags as if they were boxes and forget about the handles. The problem with lifting bags by the handles is that it's too awkward because of the twisting and turning involved in loading, unloading, lifting and relocating bags of various sizes and weights. Also, the symptoms for injury are very misleading. It's not the sudden pain; it's the gradual deterioration/damage to the muscle over time that results in a sharp pain while either lifting a bag or just getting out of bed in the morning.

I pulled a groin muscle, though I thought I was using proper lifting techniques. My doctor told me I probably was using proper techniques. But she also pointed out that unlike the gym where I know I'm lifting a certain amount of weigh and regulate my effort accordingly, luggage comes in at various times and at various weights. She said I probably do use good lifting techniques when I know I'm lifting a heavy bag. But after that, my muscles relax and if there's a light bag, I probably lift it without much effort. Yet I'm still stressing the muscles even when handling a light bag. What she said I should do is stretch my muscles during periods of inactivity so they stay warmed up and limber. Never heard of that before, but I try to stick to that routine as much as possible.

The second cause of injury comes from poor ergonomics in the design of ETD and EDS machines. Screeners are required to pick up a bag to load it on the machine, pick up that bag to unload it and either carry it to a designated location for turning it over to an airline representative or, if there's an EDS alarm, take it to an ETD table. At the table, the screener may have to lift the bag onto the table in order to search it, then lift the bag off the table and carry it to the designated location for airline handling. So even in cases where screeners are using proper lifting techniques, the poor ergonomic design of baggage screening puts screeners in situations where they may injure themselves. This is why I'm all for an in-line baggage conveyor system where a screener doesn't have to touch the bag except to search for a specific item that's been identified by the CTX operator. It should drastically cut down on the number of injuries.

The third cause of injury comes from plain old accidents. There are a lot of moving parts at an airport. Common injuries result from bag parts hitting screeners and/or bags falling on screeners. There are a lot of carts moving around on the floor, and accidents do happen. In the back, baggage handlers drive around in their tugs, and there is also another potential for accidents. Point is that when you have people and equipment moving around trying to stay within a timeline, you're bound to have plain old everyday accidents.