Asbestos is a naturally occurring mineral that has been linked to human lung disease. It has been used in a huge number of products due to its high tensile strength, relative resistance to acid and temperature, and its varying textures and degrees of flexibility. It does not evaporate, dissolve, burn or undergo significant reactions with other chemicals. Because of the widespread use of asbestos, its fibres are ubiquitous in the environment. Building insulation materials manufactured since 1975 should no longer contain asbestos; however, products made or stockpiled before this time remain in many homes. Indoor air may become contaminated with fibres released from building materials, especially if they are damaged or crumbling.

One of the three types of asbestos-related diseases is asbestosis, a process of lung tissue scarring caused by asbestos fibres. The symptoms of asbestosis usually include slowly progressing shortness of breath and cough, often 20 to 40 years after exposure. Breathlessness advances throughout the disease, even without further asbestos inhalation. This fact is highlighted in the case of a 67-year-old retired plumber. He was on ramipril to treat his hypertension and developed a persistent dry cough, which his doctor presumed to be an ACE inhibitor induced cough. The ramipril was changed to losartan. The patient had never smoked and did not have a history of asthma or COPD. His cough worsened and he complained of breathlessness on exertion. In view of this history and the fact that he was a non-smoker, he was referred for a chest X-ray and to the local respiratory physician. His doctor was surprised to learn that the patient had asbestosis, diagnosed by a high-resolution CT scan. The patient then began legal proceedings to claim compensation as he had worked in a dockyard 25 years previously, during which time he was exposed to asbestos.

There are two major groups of asbestos fibres: the amphibole and chrysotile fibres. The amphiboles are much more likely to cause cancer of the lining of the lung (mesothelioma) and scarring of the lining of the lung (pleural fibrosis). Either group of fibres can cause disease of the lung, such as asbestosis. The risk of developing asbestos-related lung cancer varies between fibre types. Studies of groups of patients exposed to chrysotile fibres show only a moderate increase in risk. On the other hand, exposure to amphibole fibres or to both types of fibres increases the risk of lung cancer twofold. Although the Occupational Safety and Health Administration (OSHA) has a standard for workplace exposure to asbestos (fibres/millilitre of air), there is debate over what constitutes a safe level of exposure. While some believe asbestos-related disease is a 'threshold phenomenon', which requires a certain level of exposure for disease to occur, others believe there is no safe level of asbestos.

Depending on their shape and size, asbestos fibres deposit in different areas of the lung. Fibres less than 3mm easily move into the lung tissue and the lining surrounding the lung. Long fibres (greater than 8mm) cannot be completely broken down by scavenger cells (macrophages) and become lodged in the lung tissue, causing inflammation. Substances damaging to the lungs are then released by cells that are responding to the foreign asbestos material. The persistence of these long fibres in the lung tissue and the resulting inflammation seem to initiate the process of cancer formation. As inflammation and damage to tissue around the asbestos fibres continues, the resulting scarring can extend from the small airways to the larger airways and the tiny air sacs (alveoli) at the end of the airways.

There is no cure for asbestosis. Treatments focus on a patient's ability to breathe. Medications like bronchodilators, aspirin and antibiotics are often prescribed and such treatments as oxygen therapy and postural drainage may be recommended. If symptoms are so severe that medications don't work, surgery may be recommended to remove scar tissue. Patients with asbestosis, like others with chronic lung disease, are at a higher risk of serious infections that take advantage of diseased or scarred lung tissue, so prevention and rapid treatment is vital. Flu and pneumococcal vaccinations are a part of routine care for these patients. Patients with progressive disease may be given corticosteroids and cyclophosphamide with limited improvement.

Chrysotile is the only form of asbestos that is currently in production today. Despite their association with lung cancer, chrysotile products are still used in 60 countries, according to the industry-sponsored Asbestos Institute. Although the asbestos industry proclaims the 'safety' of chrysotile fibres, which are now imbedded in less friable and 'dusty' products, little is known about the long term effects of these products because of the long delay in the development of disease. In spite of their potential health risks, the durability and cheapness of these products continue to attract commercial applications.

Asbestosis remains a significant clinical problem even after marked reductions in on-the-job exposure to asbestos. Again, this is due to the long period of time between exposure and the onset of disease.

An important component of a patient's history and physical examination is the question of 'medication compliance,' the term used by physicians to designate whether, or not, a patient is taking his or her medications. Many a hospital chart bears the notorious comment 'Patient has a history of non-compliance.' Now, under a new experimental program in Philadelphia, USA, patients are being paid to take their medications. The concept makes sense in theory – failure to comply is one of the most common reasons that patients are readmitted to hospital shortly after being discharged.

Compliant patients take their medications because they want to live as long as possible; some simply do so because they're responsible, conscientious individuals by nature. But the hustle and bustle of daily life and employment often get in the way of taking medications, especially those that are timed inconveniently or in frequent doses, even for such well-intentioned patients. For the elderly and the mentally or physically impaired, US insurance companies will often pay for a daily visit by a nurse, to ensure a patient gets at least one set of the most vital pills. But other patients are left to fend for themselves, and it is not uncommon these days for patients to be taking a considerable number of vital pills daily.

Some patients have not been properly educated about the importance of their medications in layman's terms. They have told me, for instance, that they don't have high blood pressure because they were once prescribed a high blood pressure pill – in essence, they view an antihypertensive as an antibiotic that can be used as short-term treatment for a short-term problem. Others have told me that they never had a heart attack because they were taken to the cardiac catheterization lab and 'fixed'. As physicians we are responsible for making sure patients understand their own medical history and their own medications.

Not uncommonly patients will say, 'I googled it the other day, and there was a long list of side effects.' But a simple conversation with the patient at this juncture can easily change their perspective. As with many things in medicine, it's all about risks versus benefits – that's what we as physicians are trained to analyse. And patients can rest assured that we'll monitor them closely for side effects and address any that are unpleasant, either by treating them or by trying a different medication.

But to return to the program in Philadelphia, my firm belief is that if patients don't have strong enough incentives to take their medications so they can live longer, healthier lives, then the long-term benefits of providing a financial incentive are likely to be minimal. At the outset, the rewards may be substantial enough to elicit a response. But one isolated system or patient study is not an accurate depiction of the real-life scenario: patients will have to be taking these medications for decades.

Although a simple financial incentives program has its appeal, its complications abound. What's worse, it seems to be saying to society: as physicians, we tell our patients that not only do we work to care for them, but we'll now pay them to take better care of themselves. And by the way, for all you medication-compliant patients out there, you can have the inherent reward of a longer, healthier life, but we're not going to bother sending you money. This seems like some sort of implied punishment.

But more generally, what advice can be given to doctors with non-compliant patients? Dr John Steiner has written a paper on the matter: 'Be compassionate,' he urges doctors. 'Understand what a complicated balancing act it is for patients.' He's surely right on that score. Doctors and patients need to work together to figure out what is reasonable and realistic, prioritizing which measures are most important. For one patient, taking the diabetes pills might be more crucial than trying to quit smoking. For another, treating depression is more critical than treating cholesterol. 'Improving compliance is a team sport,' Dr Steiner adds. 'Input from nurses, care managers, social workers and pharmacists is critical.'

When discussing the complicated nuances of compliance with my students, I give the example of my grandmother. A thrifty, no-nonsense woman, she routinely sliced all the cholesterol and heart disease pills her doctor prescribed in half, taking only half the dose. If I questioned this, she'd wave me off with, 'What do those doctors know, anyway?' Sadly, she died suddenly, aged 87, most likely of a massive heart attack. Had she taken her medicines at the appropriate doses, she might have survived it. But then maybe she'd have died a more painful death from some other ailment. Her biggest fear had always been ending up dependent in a nursing home, and by luck or design, she was able to avoid that. Perhaps there was some wisdom in her 'non-compliance.'