So occupational lungdiseases are diseases of the lung that occur inresponse to some occupational or some work-related exposure. And at least in the developed world, the most common type ofoccupational lung disease is occupational, occupational,occupational asthma.
So the most common type ofoccupational lung disease is occupational asthma. And you’ve probably heardof plain old regular asthma before but what distinguishesoccupational asthma from regular old asthma isfirstly, that occupational asthma is something that develops in adulthood. So it’s a type of adult onset asthma. And secondly, occupationalasthma occurs in response to some trigger that’s found at work. So these patients will oftenexperience signs and symptoms of asthma when they’re at work, when they’re exposed tothis trigger at work. But when they come home, withina few hours of coming home, these symptoms will resolve on their own. And on days that they don’t go into work, such as let’s say the weekend, they don’t experience thesesigns and symptoms of asthma. So here’s a lung, okay. And let’s say I was to take across-section of one of these airways like that and I wasto look at that head on, so that this is my eye over here, what I would see wouldbe something like this. I’d see the wall of the airway. This is the wall of the airway end. On the inside, this isthe inner lining or– Actually, that’s not really good. So on the inside what I’dsee is the inner lining of the airway. So that this hole in the center is a lumen through which the air actually travels, so this white arrow that I’mdrawing is the air traveling through lumen of the airway.
So what happens in occupationalasthma is in response to some work-related trigger,some work-related trigger, a couple of changes occur to this airway. So firstly what happens to the airway is that it becomes smaller. So you can see this airway issmaller than it normally is. And secondly, you see that– Secondly, you see thatthe lumen of the airway becomes smaller as well. And just looking at this veryplain and simplistic diagram, you can see that trying tobreathe through this airway is much more difficult thantrying to breathe through a normal airway and thisis what accounts for the symptoms of asthma. So I guess what’s left toexplore is what are these work-related triggersthat I’m talking about. And actually, there have beengreater than 350 described causes of occupational asthma. And at least in the UnitedStates, the most common cause, one of the most common causesis different types of flours. So that bakers are at an increased risk. And also different types of isocyanates. And isocyanates are these molecules that different industryworkers, such as plumbers, such as plumbers and thosewho work with roofing and painters can oftentimes become exposed to and also insulators canbecome exposed, too. And something that is reallyimportant to keep in mind, is that even though thereare 350 identified causes, not everyone exposedto one of these causes is going to develop occupational asthma. So occupational asthma, most common type ofoccupational lung disease. Now let’s move on to anothertype of occupational lung disease and that is– Let me get that squared away. And that is mesothelioma,so meso, meso, thelioma. Mesothelioma. And I’m sure you’ve heardof mesothelioma before, because it’s hard towatch even a day of TV without encountering one ofthose ads about mesothelioma. And how you or a lovedone with mesothelioma are entitled to compensation. So what is mesothelioma? Well, first, let’s explorethe linings of the lungs. So in pink over here, yousee the visceral pleura. So this is the lining of thelung that’s directly adjacent to the lung, closest to the lung. And then what you see in orange over here, is the parietal pleura,the parietal pleura. So the parietal pleura isthe lining of the lung, that’s adjacent to the chest wall, so further away from the lung. Now the pleura or the lining of the lung, is made up of cells called mesothelial, mesothelial cells. And mesothelial cells havethis really important function.
They secrete this fluidthat comes in between these two layers of the pleuraand this fluid is really important because itreduces the friction between the two layers of the pleura. And mesothelioma is acancer of mesothelial cells. And the reason why weconsider it an occupational lung disease is because mesothelioma is related to asbestos exposure. It’s related to asbestos exposure. And asbestos exposureoccurs with many types of occupations such as painters. Painters can be exposed to asbestos, as can shipyard workers. Shipyard, shipyard workers,and also those in plumbing. So plumbers can alsobecome exposed to asbestos. And something, unfortunately,to keep in mind about mesothelioma is that,unfortunately, mesothelioma has a very high associated mortality, a very high associated mortality. And so those are two of the,two types of occupational lung diseases and now we’llconsider some other types.