 Imagine a situation in which you are driving behind this loaded truck on a dusty road and for some reason you are not able to roll up your window shields and all this dust is getting inside your car and you have no way out but to breathe that dusty polluted air. How will you feel? Well, even imagining this must have made you uncomfortable right? Now think of workers who construct roads. They have to stay in situations like these for hours or have a look at this picture. This is from the sandstone mines of Rajasthan and I read in a news article that people who work in these sandstone mines, they don't leave more than 45 to 50 years of age. How sad is that? Because you see what situation they are exposed to. They don't have proper preventive equipments. They keep inhaling these dust particles and the dust keep accumulating in their lungs and alveoli for years and thus giving them a very short lifespan. And this is true for any occupation in which the employees are exposed to dust particles. They develop a type of respiratory disorder which we call occupational respiratory diseases or we also call them nemoconiosis. Nemo means lungs. Coney means dust and oses means an ongoing disease. Now let's have a look at the lungs of a person with nemoconiosis. Let's look deep inside their lungs and see what goes wrong. So here is the lungs enlarged. These are the alveoli and they will have close association with the blood capillaries. Now when the person inhales the dust particle and dust particle which is less than 10 micrometre in diameter enters the respiratory tract, it has the capacity to slowly pass through this respiratory tract and settle in these alveolar sacs because they are so so tiny. Okay? Once they enter the alveolus, they will have to face the immune cells present there. So let's just write IC for immune cells that are present there. These are the immune cells, okay? And let's say these are the dust particles that entered. Now the immune cells will initially tackle the dust that has entered the alveolus, okay? But here we are talking about nemoconiosis, a condition in which a person is always exposed to dust particle, it is due to his occupation mainly. So the immune cells there will give up the battle after some time. They will not be able to fight the dust that will enter the lungs every single day. So the dust particle will get a chance to settle on these alveolar cells and will gradually try to destroy these alveolar cells, okay? So let's say these are the cells that got destroyed. One here, the other here and maybe one here. Now every time a cell is dead or damaged, our body has its natural mechanism to heal it, just like how your cut or wound is healed within three to five days without you even bothering about it. Just the same thing happens here. And this happens because the dead and damaged cells, they send out signals asking for help and those signals are released in the form of chemicals, okay? So they release certain chemicals in their periphery which is recognized by few cells which are in their periphery, okay? And these cells in case of alveolus are fibroblast cells. These fibroblast cells are naturally there and they are responsible to form the extracellular matrix, the basement membrane. You will remember this if you have watched the video of diffusion membrane, okay? Where we discussed about this yellow colored lining which is the extracellular matrix forming the basement membrane. So this extracellular matrix is present outside the cells everywhere in every organ of your body. And as we just discussed, it is produced by these fibroblast cells. And this fibroblast cells becomes hyperactive in response to any damage or any wound in the body, okay? And they start secreting the extracellular fluid, extracellular matrix or in this case they start secreting a lot of collagen fiber. And the fibroblast cells release collagen with the aim of healing the damaged tissues, right? But as we are talking about the occupational respiratory disease in which the dust particle will keep coming into the alveolus, okay? There is no stop to that. So it will keep damaging these cells of the alveolar membrane and these cells will keep sending the signals to the fibroblast asking for help. So in turn what happens is the fibroblast cells end up producing way too much of collagen fiber in the periphery, making the entire structure of the alveolus very stiff and non-elastic. And we know that the blood capillary will sit very close to the alveolar membrane but due to the production of extra collagen in the periphery, there will be obstruction between the alveolar membrane and the blood capillaries as well. This will definitely obstruct the gaseous exchange between the alveolus and the blood, right? And this condition of the lungs is also called fibrosis. Now the severity of fibrosis will depend on the concentration of dust in the air and also on the period of exposure. And again, nemoconeosis is actually an umbrella term, okay? Depending upon the type of dust particle a person is exposed to or depending upon the chemical composition of the dust, each disease, each respiratory disease has given a different name. The first and the most famous one is silicosis. And from the name you can guess that it is a disease due to the exposure to silica dust. And do you know that silicosis was first reported by the workers in the Kolar gold mines or the Kolar gold fields? If you have watched the movie KGF, which is a famous South Indian movie, you will know what I'm talking about. This movie clearly shows the poor condition of the gold mine workers and the silicosis disease was first reported in the workers of the Kolar gold fields. Next to silicosis, the most common nemoconeosis is anthracosis. Anthrac means coal. So it is a nemoconeosis due to coal dust. It happens to coal mine workers. It is also called as coal workers nemoconeosis or the black lung disease, because this is what their lungs look like after years of exposure to coal dust. Next we have another famous nemoconeosis, which is called asbestosis. It happens because of the exposure to asbestos. Now asbestos is a naturally occurring fibrous silicate mineral, but it is again of different types and are used in various different industries for different purposes. It can be used in the cement factories, the fireproof textile industries, in roofers, in shipping industries and is one of the topmost nemoconeosis causing dust particle. Next in the list is bisinosis. It is a nemoconeosis caused due to the exposure to cotton fibres which is suspended in the air and it happens to people who works in cotton textile industries. So these are a few different types of nemoconeosis, but there are so many more depending upon the different chemical composition of the dust, it has given different names. Now the worst part about nemoconeosis or the occupational respiratory disorders is that they do not have any cure. Prevention is the only way.