The idea that smokers’ lungs work less efficiently should come as no surprise to anyone who has ever smoked. No scientific knowledge of the structure and function of the lungs is necessary to confirm this fact. All that is required is a handful of basic observations. Even to those with no knowledge of physiology at all, it is obvious that the lungs are not designed to smoke tobacco with. Seeing the tar collect on the kitchen tiles and feeling out of breath running for the bus, for example, should all be telling us that smoking does us more harm than good.
Amazingly enough, neither this, nor the government warnings and information availiable today on the damage it causes, is not enough to stop people smoking. It is only in recent years the risks of smoking have become more scientifically defined, and publicised, but the nicotine in cigarettes has been long recognised as a lethal poison in high quantities, and studies from the nineteenth century and earlier have shown consistently that the aerobic performance of smokers is considerably poorer than non-smokers.
We have known sine the first cigar was rolled that smoking may not be the healthiest pastime. Nowadays, we can enforce this by pinpointing why and how. The human lung contains on average 15 million alveoli. These are the air-sacs in the lungs where gas exchange takes place in the body. Oxygen from the air diffuses through the thin epithelial cells of the alveolar and capillary walls, into the surrounding capillaries, as Carbon Dioxide diffuses from the capillaries to the alveoli.
The body needs to exchange these gases as quickly and efficiently as possible if it is to function. Fick’s Law tells us that : diffusion rate = surface area x concentration gradient diffusion pathway This is the reason we have several million alveoli – to give the lungs the largest possible surface area for the O2 and CO2 to diffuse across, so increasing the rate of diffusion. If we are to pay urther attention to the way we have evolved, we might also observe that much of the respiratory tract is designed to keep out small unwanted particles that may damage these alveoli.
The nostrils contain small hairs. The nasal cavities collect debris on a layer of mucus. Protruding from this mucous layer are the cilia, tiny hair-like structures which sweep the offending foreign particles up towards the throat. Cigarette smoke contains many chemical compounds. None of them are beneficial, and a large proportion are harmful in some way or other. Smoke has been found to immobilise the cilia for several hours, and continued exposure destroys them.
While they can regenerate to an extent, smoke over a long time can erode the mucous layer so that it can no longer support the cilia. Tobacco destroys the respiratory system’s first line of defence. Other chemicals in the smoke can kill the white blood cells protecting the respiratory tract. Also, many of the chemicals are recognised as carcinogens. The very act of smoking defeats the object of a well designed system. The defences take care of any dust, debris or small insects one may encounter, but are simply not geared to deliberately inhaling large quantities of smoke.