Holmes defines "dust" as pretty much any particle 63 microns or smaller, so that includes what we normally think of as dust--dirt particles--but also various chemicals, fungal spores, bacteria, pollen, etc. She describes theories on how space dust accumulated to form stars and planets, how scientists use dust profiles to learn about meteors and other objects in space, how dust is created, how dust travels the earth, the effects of dust on the climate, and the effects of dust on health. Although Holmes frequently discusses the dust-making effects of human activity and the harmful results of that activity, this is not an environmental advocacy book. She also emphasizes that many dusts that are harmful to humans are part of the natural environment, and she explains that the effects of various dusts on the climate are complicated and not fully understood--some particles contribute to global warming, but others produce noticable cooling effects.

Holmes is, on the whole, an excellent writer. I got bogged down a little in the middle of the book (a dust overload) and stopped reading this for a while but then finished the second half in one sitting. The book is full of interesting (and sometimes troubling) facts about dust, and it highlights the complexities of the natural world. ( )