Is she able to find anything else that is in her budget that would be better for health?? I mean, if it's going to exacerbate her conditions, then she's shortchanging herself in the end, and the landlady isn't as good of a friend or as close as she'd like you to believe (pinching pennies when something would be better for her "friend's" health".)

I'd say stay where she is if it's a better environment, or find something else that will be better for her health. Compromising will only be compromising her health in the end...