Is the use of 'as' in place of 'because' considered to be poor grammar/style? For example
I cannot come with you as I am too busy
instead of
I cannot come with you because I am too busy
Learn English – Use of ‘as’ instead of ‘because’
conjunctionsgrammar
Best Answer
In some sentences as can be ambiguous, since it may be unclear whether it expresses time or cause. There is no such risk in your example, however, and you may use either as or because.
As background, causative as seems to be rarer than temporal as, and American speakers and writers seem less inclined to use causative as than British speakers and writers ('The Cambridge Guide to English Usage').