I was told by a friend about the dangers of storing flours at room temperature in tropical Singapore. I remembered reading about this a couple of weeks ago. In the article, 1g of plain flour left out in the open can have as many as 1750 dust mites crawling in it. The problem is that even when dead, the mites can cause serious problems among asthmatics. This is because the bodies of these mites can still trigger asthma attacks even when the food is cooked at high temperatures.
For me, the preferred storage area for my flour is the freezer. The freezer is great, especially for wholemeal flours. At room temperature, the oils in the germ can turn rancid rapidly. However, this is greatly inhibited at freezer temperatures. I use up flour quite rapidly also as I bake very regularly and in larger quantities than most homebakers.
The following is a link to that article that appeared in the Straits Times.