Although you could interpret it as "while" and have it make sense, in this case, I would say it means "because". If you consult Learner's Dictionary, you'll find the fifth definition for 'as' used as a conjunction is:
formal : for the reason that : because
- She stayed home as she had no car.
- As I'm a pacifist, I'm against all wars.
The reason I wouldn't interpret it as "while" is because I think it sounds odd to use it that way without the progressive form (however, there's no rule that it can't be done). The following sentence is an example of where I would interpret it as "while":
As I was going to the store, she was driving to work.
As you can see, 'as' is a very versatile word, so it has a lot of uses (for instance, I've used it multiple times in answering your question!)