Is it permissible for a woman to wear trousers and a blouse, remove her hijab, and apply makeup in a workplace consisting entirely of women, or must she wear an abaya and remove her makeup upon exiting?

The Muslim woman is commanded to observe hijab in front of men who are not her mahram. She must conceal herself from them and not display any of her adornments to them. However, in places designated exclusively for women, there is no harm in her not wearing an abaya, or in applying makeup and the like.