As a society, my feeling is that we don't put enough emphasis on protecting our lungs against harmful macro and microscopic particles; this is a huge mistake, as reduced lung capacity is, in my mind, more damaging to quality of life than say, sub-optimal digestion, mild to moderate liver dysfunction, or even reduced cardiac output. If you strongly disagree with this opinion, I'm willing to bet that you'll change your mind if you spend some time in any intensive care unit and sit by a few patients who are unable to properly oxygenate their blood because of reduced lung capacity - this is a heart-wrenching scenario, one that I don't wish upon the grouchiest people I know.

Why are healthy lungs so vital to the rest of your organs and body parts? It's within the very thinnest branches of tissue that line the base of your lungs where your body accepts oxygen from your environment and expels carbon dioxide. Without this ongoing exchange of gases, you can't adequately convert nutrients from food into usable energy.

As a part of every routine physical evaluation, I look for signs of lung dysfunction with the following measures:

Inspection I look for signs of strained breathing; sometimes, it's as subtle as seeing overuse of smaller muscles in the neck region in an effort to assist ribcage expansion during laboured inhalation. Other obvious signs of lung dysfunction are slightly purple/blue lips or fingernails, and audible distress with breathing. Palpation Placing my hands symmetrically on both sides of the posterior aspect of a person's ribcage, I want to see my hands move about the same amount during deep inhalation. Assymetrical movement might indicate abnormal presence of fluid or air in the space between the lungs and the chest wall. I also want to feel the transmission of the person's voice as vibration (called tactile fremitus) against my palms as they're pressed up against his chest wall - physicians will typically ask you to repeat a phrase like "ninety-nine" while assessing tactile fremitus. Abnormally strong vibration can indicate fluid accumulation within lung tissue, while decreased fremitus might mean that there is fluid build-up between the lungs and chest wall. Percussion To help confirm palpatory findings, percussion is used, whereby I use my hands to steadily percuss against the chest wall while listening to how hollow or full the chest cavity sounds along different points. This is much like tapping a wall to detect the presence of a stud - where there is a hollow sound on percussion, I know there is air; where there is a full, deadened sound on tapping, I know that there is something substantial behind the chest wall that is absorbing my percussive force, likely fluid associated with inflammation. Basically, I'm hoping for a slightly hollow sound on percussion to indicate normal presence of air in the lungs - I don't want the feedback to be too resonate, which is characteristic of chronic obstructive pulmonary disease, or too dead, which usually means that there is unwanted fluid in the area. Auscultation Auscultation is the process of listening to lung sounds with a stethoscope. During auscultation, I'm hoping to hear what we call "vesicular breath sounds," which is to describe a mild influx of air with inhalation, and little sound during exhalation. Whistling-type noises, scratchy sounds, noise that resembles what you hear when breathing through a snorkel, gurgling, and an abnormally quiet lung field all indicate some form of distress.

Here's the thing: you don't want to wait for your doctor to stumble upon an abnormal finding before becoming mindful of what you're breathing in during everyday activities. In most cases, by the time I come upon a significant finding using the screening procedures described above, chances are that dysfunction and disease have been at play for a good while.

Living in a neighbourhood with good air quality is a huge plus. But the most important priority in preventing lung disease is to minimize exposure to concentrated sources of lung irritants, and where such exposure is near impossible to avoid, it's vital to take proper precaution with optimal ventilation and protective gear.

For example, when sanding down minor repair jobs, drilling into wood, or doing any other basic chores that require being close to even a small cloud of dust, as much as it might seem going overboard, I think it's well worth the effort to wear a respirator with a decent filter, something as simple as the one found here:

3M Low-Maintenance Half-Mask Organic Vapor Respirator

This sort of protective gear is absolutely essential if you're taking on an extended project that involves steady exposure to dust, a good example being landscaping work where there is regular cutting of fresh stone, which kicks up all sorts of lung irritants like fibreglass and carborundum grit. (Crystalline silica and mica in drywall dust are probably the most common workplace lung irritants in first world nations.)

To those who tell me that they cut stone or sand drywall joints for a living and feel fine after taking a good long shower after work (all without wearing a respirator), I remind them that repeated exposure to irritants can lead to numbing of our natural feedback mechanisms, kind of like how a smoker eventually learns to inhale tobacco smoke without experiencing much of a negative physiological reaction. But if you think back to the first few times you were exposed, you're likely to remember your body's attempts to eliminate harmful particles through sneezing, coughing, tearing up, mucous production, and perhaps even an infection deep within the lungs. Bottom line: please don't neglect use of an effective respirator.

The most common lung irritants tend to harden when they come into contact with moisture. So even a few times of being exposed to concentrated stone, wood, sanded drywall mud, or other type of construction-related dust can cause acute lung tissue damage and lead to development of any number of lung problems, the more common ones being fibrosis and cancer. Just think of each particle of dust as a tiny metal-like shard, and imagine the damage that occurs when millions of these particles enter your lungs over the course of a couple of hours.

Please remember that it's not just visible dust that you should strive to avoid and protect yourself against. If chemicals that you work with give off strong smells that make you feel nauseous, you need to figure out how to avoid these substances - nausea that's triggered by stimulation of your olfactory system is a strong sign that you're in the presence of lung irritants that, over time, can create irreversible damage.

Here's a look at six substances that are highly capable of causing lung damage:

1. Crystalline silica

Crystalline silica is a component of soil, sand, and rocks (like granite and quartzite). Only quartz and cristobalite silica that can be inhaled as particles are designated known carcinogens.

Where is it found?

In the air during mining, cutting, and drilling.

Drywall mud, household cleaners, paints, glass, brick, ceramics, silicon metals in electronics, plastics, paints, and abrasives in soaps.

Occupations most at risk:

Quarry workers, plasterers, drywallers, construction workers, brick workers, miners, stonecutters (including jewellery), workers involved in drilling, polishing, and crushing, pottery makers, glassmakers, soap or detergent manufacturers, farmers, dentists, and auto workers.

2. Wood dust

Wood dust is made up of particles of wood that are created by cutting and sanding.

Where is it found?

Anywhere wood is chipped, turned, drilled, or sanded.

Occupations most at risk:

Those in the construction industry, and to some extent, those in the logging industry. Specific occupational settings that typically involve significant exposure include furniture/cabinetry shops, timber mills, window/door manufacturers, joinery shops, wooden boat manufacturers, and pulp and paper manufacturers.

3. Asbestos

Asbestos is a group of naturally occurring minerals that form heat-resistant fibers.

Where is it found?

Naturally in rock formations.

In some auto parts like brakes, gaskets, and friction products.

In some industrial textiles.

In some safety clothing.

Occupations most at risk:

Asbestos miners, brake repair mechanics, building demolition or maintenance workers, carpenters, cabinetmakers, construction workers, electricians, plumbers, plaster and drywall installers, auto mechanics.

4. Chromium (hexavalent)

Chromium is a naturally occurring mineral that becomes carcinogenic when it is transformed into its hexavalent form through industrial processes.

Where is it found?

In the manufacturing of stainless steel and other alloys.

In the industrial wood preservative, CCA (Chromated Copper Arsenate).

Used in small amounts in printer ink toners, textile dyes, and during water treatment.

Occupations most at risk:

Welders while welding stainless steel, printing machine and press operators, machinists, and pipefitters.

5. Nickel and its compounds

Metallic nickel, a possible carcinogen, is a silver-like, hard metal or grey powder. Nickel compounds, known carcinogens, tend to be green to black, but yellow when heated.

Where is it found?

Used to make stainless steel, and also found in magnets, electrical contacts, batteries, spark plugs, and surgical/dental prostheses.

Occupations most at risk:

Welders, construction millwrights, industrial mechanics, metal spraying workers, machinists, machining/tooling inspectors, nickel refinery workers, iron/steel mill workers, metal ore miners, and manufacturers in structural metals, motor vehicle parts, boilers, and shipping containers.

6. Formaldehyde

Associated cancers:

Nasopharyngeal cancer, leukemia

What is it?

A colorless, combustible gas with a pungent odour.

Where is it found?

Used in the manufacture of textiles, resins, wood products, and plastics.

As a preservative, formaldehyde is found in embalming fluid.

As a preservative and disinfectant, it's used in soaps, shampoos, deodorants, mouthwash, and cosmetics.

Occupations most at risk:

Embalmers, pathology lab operators, wood and paper product workers, and health care professionals (nurses, dentists) exposed during use of medicinal products that contain formaldehyde. Also at risk are painters, manual labourers, product assemblers, foundry workers, and those who teach in cadaver laboratories.

How Important Are Your Lungs?

Consider that of the total amount of waste materials that your body eliminates via urine, stools, mucous, breath, and sweat, approximately 75 percent by volume is handled by your lungs. Put another way, your lungs are at least as important to your body's ability to experience ongoing cleansing and detoxification as your digestive tract and kidneys. And to maintain healthy lungs, you have to minimize your exposure to the pollutants described above.

Beyond avoiding concentrated pollutants, here are a few tips to help ensure healthy gas exchange within your lungs: