Natural mineral dusts and their respiratory health hazard

Breathing in natural dusts, such as volcanic ash, coal dust and dust from desert dust storms can cause fatal lung diseases. These dusts are produced around the world and can be transported great distances, affecting many millions of people. Often, those most affected are poorer people who work in mines, quarries or other dusty places. Not all dusts are equally harmful, however. We're not sure what makes different dusts harmful, but the properties of the minerals in the dusts will influence how harmful a dust is, as well the amount of dust breathed in. Some dusts can cause an incurable disease called pneumoconiosis, if breathed in for many years. Like smoking, it can take decades of breathing in the particles before any disease is noticed. There are different kinds of pneumoconiosis depending on the dust that a person has been inhaling. If someone breathes in crystalline silica, a particularly dangerous mineral, they may develop silicosis whereas coal miners develop 'black lung' also known as Coal Workers' Pneumoconiosis (CWP). Often, coal dust contains lots of silica, but the miners get CWP instead of silicosis. This makes us think that something stops the silica from being harmful in coal dust. I will be studying several kinds of dust to find out why some dusts containing silica are more harmful than others. Some researchers have suggested that the silica particles are coated with clay in some circumstances. It is known that clay is not harmful to the lungs, so a clay coating might protect the lungs from the silica. Miners from mines that produce very high-quality coal are more likely to get ill than miners from mines with poor quality coal. I will study coal dust from these different mines to see whether the poor quality coal has more clay-coated silica. I am also going to study the surface of volcanic ash particles. Many experts are worried that volcanic ash could cause diseases like silicosis because it contains lots of crystalline silica particles. The ash doesn't seem to be that harmful though. I will investigate whether the silica is coated, perhaps with glass (this is likely because of the way the silica forms in volcanoes). I will also study desert dust storms. Millions of people are affected by these and there is evidence that some storms cause pneumoconiosis. So far nobody has ever studied the particles to see what they are made of or even if they are small enough to get into the lung. In order to do this work I will be developing new techniques for looking at these tiny particles, which are 1000 times smaller than a pin head! I want to be able to see what different parts of particles are made of. I will be using different kinds of electron microscopes at the University of Cambridge and the Natural History Museum (NHM), which allow me to focus on the particles and then analyse their composition. At Cambridge there is a group of researchers who study the formation and structure of minerals and they will be advising me on how to use the microscopes and the best techniques available. I will also be working with Dr. Ben Williamson at NHM, who is an expert in electron microscopy and analysis of fine particles. I will also work in Italy with Prof. Bice Fubini who is an expert in the reactions which occur between particles and cells in the lung. I will be based in Cambridge, which is home to the world's expert on the health effects of volcanic eruptions, Dr Peter Baxter. He will advise me on how we can use my work to help set exposure standards which take into account the features that make particles toxic: currently they are based on the mass of dust breathed in, but the state of the surface of particles may be more important. At the end of this project, I will be able to tell if some dusts are less harmful because the crystalline silica in them is coated. This will be a great step forward in our understanding of the health hazards of natural dusts.