Harmattan comes yearly across the West Africa sub region and Saharan. Harmattan can be well enjoyed, but all depend on your preparation for it.
Harmattan last for a couple of weeks before it wears off, during and after which its effect are felt. For the purpose of its health implication, Harmattan should be taken seriously, well not in another continent but in the West Africa sub region and the Sahara.
During Harmattan, the weather is cold, dry and dusty.
Harmattan comes with its effect, but can be well managed, if you have a good idea on how best to manage it.
There is lot of things one you need during harmattan such as;
Cotton jacket
Blanket
Wet lips
Disposable nose gloves
Jelly body cream
http://healthful.com.ng/important-to-have-during-harmattan/

Citrus or any other fruits with lots of Vit. C. Helps with the cold.

you're right gaborone