"Everything counts in large amounts." -Depeche Mode
Science writer Hannah Holmes uses the Biblical "dust to dust" adage as a thread weaving through her eleven easy to read chapters, beginning with a sort of overview in Chapter 1. We begin as stardust, and it is to stardust we shall return. Eventually. In Chapter 2, "Life and Death among the Stars," she introduces cosmic dust and in Chapter 3 shows it falling on the earth from outer space: forty thousand tons of it every year, almost all of it in a fine rain. (p. 33) Then there are three chapters on how dust moves around on our planet and how it affects the weather, the life cycles of plants and animals, our economies and our health. There is an excursion into the past in Chapter 7 to answer the question, "Did Dust Do in the Ice Age?" Chapter 8 is about the continuous fall of atmospheric dust onto land, ocean and ice. It is finally in Chapter 9 that Holmes considers the dust in our neighborhoods, and then in Chapter 10, "Microscopic Monsters and Other Indoor Devils," she gets to the topic of primary interest to most readers, the dust under the bed, in the rug, and on the floor. The final chapter is about the dust of our bodies after we are dead, and then after the sun explodes and we are once again stardust.
This is a fascinating read that unlike most books becomes more interesting the further into it one gets. It may change the way you view the world. Seeing our planet and its history from the point of view of dust sheds an entirely different light on things. The very small things in enormous numbers affect our lives in ways that surprise and astound. Consider the sheer volume and weight of dust that swirls around in the atmosphere, with massive tons of it held aloft to cross oceans and continents. That story alone is mind boggling. Here I learned that the coral islands of the Caribbean developed their soil not from the breakdown of the islands themselves, but from the sand that fell on them over millions of years from the Sahara Desert thousands of miles away!
This, the relatively unknown story of dust is a story of dust hunters who collect and analyze the minute particles from all over the planet to determine their origin and how they affect the various environments. Dust hunters even drill into the arctic and the antarctic to reconstruct the story of dust laid down in the past. They can tell by the composition of dust where it came from. Saharan dust, for example, is particularly heavy in iron and phosphorous. In fact, the microbes in dust, the viruses, the fungi and the bacteria, can betray its origin.
Holmes considers some hot topics in science along the way, including global warming and the explosion in asthma in the United States and Europe in recent decades and how dust may or may not be the cause. Deadly dusts containing asbestos, quartz, coal, etc. are considered as well as the danger of working with materials containing them. Why talcum powder is no longer dusted on babies and how working with pigs and wheat and other farm products can be hazardous to your health is revealed. The deadly effect of dust getting into the lungs is explained--how macrophages can and cannot engulf and get rid of various substances and how people die from a host of diseases caused by inhaling the wrong kind of dust. And Holmes doesn't disappoint when it comes to the story of household dust. The chapter on indoor dust is absolutely fascinating and a bit scary.
Some other things I learned is how dust heats or cools the planet as it floats in the air or lands on ocean, land or ice; how epidemics can be triggered by migrating dust containing disease spores; how a bloom of algae can follow a download of iron-bearing dust from a desert half a world away; even how we carry around with us our own personal and distinctive cloud of dust.
Some readers I suspect will grow impatient with all the science and want to know about their own dust. I know I felt that way when I opened the book. But I am glad I read the whole thing, because what I learned about dust makes me shake my head in wonder. This is an information-packed book. There's no padding, and everything is vividly expressed.