Asthma
Asthma in children in intact families is usually not a problem. In families of divorce the problem can be grave, as asthma is potentially a fatal illness. Of course, the problem of allergies flaring up the asthma is related.
I obtained an excellent power point from an MD, which shows how important it is to keep asthma under control. When asthma is not controlled, it can become very dangerous. Often, one parent may not understand this.
The courts tend to feel that after divorce each parent is entitled to have his/her home the way he/she likes it—including some degree of dust, pets, etc. So judges are hesitant to address conditions that aggravate allergies and asthma—except smoking. They are more likely to issue an order that the child not be around second hand smoke than other problematic substances.
This problem can lead to another problem—accusations of Munchausen by Proxy, if one parent alleges symptoms, and the other denies any problem. When that happens, allergy tests should be done, and other ways of ruling out medical issues should be used rather than labeling one parent.