My little sister was assigned this question for her science class. I know that loads of bacteria are naturally present all over our body, I just don’t know the names or exactly why they’re there.
Anybody know?
Thanx in advance,
Star Light
As if the question in the op wasn’t enough…
My sis just imd me and added on the following questions…
Can bacteria be deadly?
How much bacteria is on your hands after you wash them?
What type of bacteria in the air can effect your results?
Any help with these as well would be greatly appreciated.
A wide variety of bacteria grow on human skin, and since I’m not a microbiologist, I’m not intimately familiar with the subject.
I have been able to find a useful site on the internet that describes the normal microflora of human skin: here you go
As to why they live there, I believe the best answer (and there are multiple correct answers) is that they can obtain water, nutrients, and find a hospitable environment on our skin.
Bacteria can be deadly (Baccilus anthracis is an example that comes rapidly to mind because of current events).
I don’t know specifically about how many remain after washing hands, but I’d suspect many do. Merely washing the hands is not going to effectively remove the entire microflora of your skin. If it did, recolonization would rapidly take place due to the incredible numbers of these bacteria.
Sorry, can’t help you about bacteria in the air, I don’t know anything about that off the top of my head.
Thanks for the link, Gaspode. The archive was the first place I went to, actually. While the discussion is certaintly interesting, I don’t think it’s quite appropriate for a 9th grade science class. 
You often get a lot of Staphylococcus species on your skin, specifically S. epidermidis and S. aureus. Skin usually isn’t a particularly hospitable environment for bacterial growth - it’s pretty dry and somewhat acidic. So you don’t get a lot, but there’s some.
Hand washing will remove fecal material that contains other types of bacteria, but don’t do a whole lot to your normal skin flora - they’re used to it.
If you’re asking which skin bacteria are deadly, well, S. aureus is about the only one that I’m aware of. It produces a toxin that can be deadly when ingested in large amounts. It’s one of the most common causes of food poisoning.
And you generally don’t get a lot of bacteria in the air. But what results are you talking about??
And just to throw my nickel in…
It’s the normal flora that grows on your skin, such as Staphylococcus epidermidis, that helps prevent the pathogenic bacteria from gaining a foothold. Dousing yourself with antimicrobial agents might not be such a good thing, popular advertising aside.