Feel free to add to this thread as you please!
For starters, a few that I would consider the bare minimum-
Respirators!
While typically a no-brainer, a lot of explorers seem to omit a respirator from their expeditions. This is an enormous risk to your health, especially with long term and repeated exposure. Ask anyone with Mesothelioma, a few asbestos particles will go a long way to ruining your health and your life down the road. A pretty good filtration mask can be picked up at most hardware stores. I'm not talking the little paper ones doctors wear either- we're talking something that covers your nose and mouth completely. Prices vary, though I wouldn't skimp on something like this- get the best filtration system you can buy.
Remember:
- Asbestos is generally odorless, and is present in many older buildings- in everything from sidings, shingles, insulation, to window-frames and doors. In crumbling abandoned structures, the odds of it being disturbed and in the air are nearly 100%, and you don't want ANY of it inside of you.
- Lead dust, tiny particulates of peeling lead paint are thick in abandoned buildings. Like asbestos, a little lead will go a long way to ruining your life. Lead and asbestos are often found together.
- Even in newer structures undetectable dangers may be present. Mold spores, mildew, and other toxins will crop up quickly in abandoned structures, and are no less dangerous than their industrial hazard counterparts listed above.
- Even the best mask CAN and WILL eventually get overloaded. Know how to inspect your filters, and know how to change them when they wear out. On a similar note, do not disturb debris in abandoned structures- you risk disturbing greater volumes of asbestos, lead, or other hazards.
Though I shouldn't have to explain this one, here it goes- if you're going into a creepy abandoned place that is likely covered in a fine layer of toxic dust, maybe wear some gloves? Simple rubber gloves (like from the doctors office) are cheap, easy to get (try the first aid section at WalMart) and you can easily dispose of them after an adventure. While it's generally not good practice to touch "anything" in abandoned buildings, you may occasionally need to open doors, maneuver objects, or use your hands to stabilize yourself. If you don't have em, get yourself some gloves. You're worth it.
" title="Wink 
">A Buddy!
I understand that exploring is a sometimes dangerous, even illegal pastime. It lends itself to a rather "lone wolf" mentality, and while that is all well and good, bear in mind your safety is the #1 concern, and there is safety in numbers. One extra person can make all the difference.
A rather extreme example was at an abandoned hospital- Pennsylvania I think, where a copper thief was working alone in the dark, and got turned around- walking through an open door not onto a staircase but an open elevator shaft. Gravely wounded in the dark in a cavernous abandoned building, he was unable to call for help, and perished. Now, that is of course a worst case scenario, and a good argument against exploring at night, but all the same- what would you do if you got into a basement and the stairs collapsed? What if you banged your head, got lost, got stuck, or otherwise were rendered unable to call for help?
That's where your buddy comes in. Even just having a lookout in a parked car can make a world of difference, and potentially save your life, though I highly recommend getting a friend involved with you. It's an adventure you can share with someone, and the odds of you getting seriously injured, trapped, or otherwise imperiled are greatly diminished. A cell phone can be a life line, until it's out of range, out of reach, or out of battery. Another thing to consider is that there is no phone app that can watch your back like a buddy can.
I'll have more I'm sure, but until then, feel free to add to this list as you see fit.
