Our lungs are the interface between blood and air. Their role in oxygenating our bloodstream is their primary function, and they bear the brunt of a lot more than just pressures of oxygen and carbon dioxide. Borne upon the air are numerous chemicals, pollutants and particles that can generate many patterns of lung disease.
Author
Dan Baumgardt
Senior Lecturer, School of Physiology, Pharmacology and Neuroscience, University of Bristol
Inner-city pollution can lead to inhalation of gases including nitrogen dioxide, which have been shown to affect other respiratory diseases like asthma. Coal dust led to a condition known as emphysema - known today as chronic obstructive pulmonary disease - in miners.
But some inhaled particles can cause unusually named diseases of their own and are more common in people who have certain jobs - or indeed certain pastimes. Asbestos is perhaps the best known example.
The history of asbestos is long and ultimately malignant. It is a naturally occurring substance - a strong, durable and heat-resistant material - and was once used extensively in the construction industry and in shipbuilding.
When asbestos breaks apart, it releases fibres into the air that can easily be inhaled. In migrating into the respiratory tract, it can first affect the lungs, generating a form of scarring that prevents them from inflating normally. This is called asbestosis.
It can also move outwards to irritate and thicken the pleura (the membranous lining of the lungs), which restricts them from expanding even further.
Perhaps the worst association is that between asbestos and the aggressive form of cancer known as mesothelioma - which is serious and sadly incurable.
The spectrum of patients afflicted with asbestos-related illnesses isn't just limited to men in the workplace either. Many wives who laundered their husbands' dirty clothes were exposed too, as were children who shared the house.
The first established diagnosis of asbestosis was in 1924. What's staggering is the delay between the first recognition of asbestos-related illness (and indeed death) in the early 1900s, before it was eventually banned from being used in some countries in the 1980s-90s, with its removal and disposal being carefully regulated.
Birds, brass and blue cheese
It isn't just your job that can put you at risk of developing certain lung diseases. Sometimes, it's the things you do with your spare time.
Take avian enthusiasts, for instance, those who keep pigeons to race or birds in the house as pets. If you are such a person, remain vigilant for chest symptoms such as persistent cough or shortness of breath, and take them seriously if they appear.
The pathology we're looking at here has the elaborate name extrinsic allergic alveolitis or EAA. In a nutshell, inflammation of the tiny air sacs of the lungs (the alveoli) generated by an allergic response to an alien particle entering the body. It shares several features with asbestosis: a cough, tightness in the chest and shortness of breath.
EAA can be diagnosed on radiographic imaging. On a chest X-ray, the lung fields have a haziness to them that looks like ground glass. It can also be investigated with blood tests and a special respiratory test where the patient blows into a tube to measure their lung volumes and airflow on exhaling. We call this spirometry.
Back to feathered friends and the problems they can cause.
Dust from feathers and bird droppings contains avian proteins that can inflame the lungs when inhaled. These can come from a variety of different bird species. It is observed in pigeon keepers, but can also be seen in poultry farmers and those who sell birds as well as keep them. Even keeping small birds, such as canaries or budgerigars, can present a risk, but so can larger birds, such as cockatiels and parrots.
EAA has other causes aside from repeatedly inhaling particles from birds. The list is both extensive and quirky, including a variety of allergens that come from many fields.
Take the culinary industry, for instance. Imagine inhaling the fungi from the rinds of blue cheeses and contracting cheese-washer's lung. Or the fungi from moulding grapes and developing wine-grower's lung. Similar particles can come off of coffee beans, molasses sugar, mushrooms and barley, each creating its own form of respiratory illness.
Those who work with dried grass or hay - farmers or thatchers, for instance - can also find themselves on the receiving end of other inflammatory fungi. Other sources include sawdust, fertilisers and mosses.
It also appears that playing music or taking a dip in the hot tub is not entirely risk free. Bacteria related to those causing tuberculosis can be inhaled from a brass instrument or the bubbling water. They're also colloquially referred to as brass player's lung and hot-tub lung.
Most of these conditions can be treated with steroids, but the primary objective is to avoid exposure to the allergen in question. For some, this is easier than others. Getting rid of a beloved pets may prove as difficult as switching careers.
Part of the difficulty may be in establishing what it is that's causing the problem. That's why it is always important for a doctor to ask about both occupation and hobbies in a consultation about respiratory symptoms.
So don't underestimate how the air we breathe can affect our lungs. Both city and country air can work their influence.
Dan Baumgardt does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
