When I first heard that explanation I thought someone was just making up the reason for the dusty air but it's not just a wives' tale. Trade winds from the Sahara do actually blow dust and sand all the way down here. During this time of year it stops raining and the air is more hazy and dryer than usual. In the last two months I've only see it rain twice and there is not substantial rain in the forecast for several months. Lately I've noticed you can look directly at the red sunsets in the evening since there is so much debris in the air.
There is a fine layer of red dust that settles on everything on a daily basis. I'm even shocked at how fast it can accumulate in some of the rooms where we have air conditioning and closed windows. I have not been running in this weather and don't intend to start strenuous exercise outside until we get some rainfall. Once the rains start again the humidity will soar but I'd still prefer that to having everything covered in dust. I found the following clip on Youtube that shows how the drastic contrast in the weather that happens during Harmattan.
I miss the rain and am looking forward to things greening up again in several months.