Our sense of taste and smell can sometimes feel like a mixed blessing. When smelling, say, warm toast or fresh cut grass, we’re reminded of the gift of this sense. But day to day life can sometimes seem like an assault on our senses, as we inhale the smells of rubbish, vehicle fumes and – of course – cigarettes.

However, foul smells have a purpose too, nudging us towards fresher, healthier air and away from dangerous fumes and contaminated food, from noxious gases to sour milk.

Thirst for clean air

We take smell for granted, but perhaps we shouldn’t, given the sheer volume of air we pump into our bodies every day. As writer Diane Ackerman poetically puts it: “Each day, we breathe about 23,040 times and move around 438 cubic feet of air. It takes us about five seconds to breathe — two seconds to inhale and three seconds to exhale — and, in that time, molecules of odour flood through our systems. We smell odours [as we exhale as well as when we inhale]. Smells coat us, swirl around us, enter our bodies, and emanate from us. We live in a constant wash of them.”

Taking our sense for granted

One of these smells, cigarette smoke, is an unfortunate component of modern life and a notorious side-effect of traditional smoking. A quick Google search will generate literally millions of theories – some conflicting and many with an air of panic – on how to get rid of it. We all know the dangers of first hand and second hand smoke, but even “third hand” smoke is a worry to many in the science community.

“Third-hand smoke refers to the tobacco toxins that build up over time,” Jonathan Winickoff, a paediatrician at the Dana–Farber/Harvard Cancer Centre in Boston told Scientific American. “One cigarette will coat the surface of a certain room [a second cigarette will add another coat, and so on]. The third-hand smoke is the stuff that remains [after visible or ‘second-hand smoke’ has dissipated from the air]….You can’t really quantify it, because it depends on the space….In a tiny space like a car the deposition is really heavy….Smokers [may] smoke in another room or turn on a fan. They don’t see the smoke going into a child’s nose; they think that if they cannot see it, it’s not affecting [their children].”

Israeli scientists have even used human aversion to unhealthy smells to help smokers quit, using rotten eggs and fish to try to create a negative association with cigarettes.

Recipe of a scent

Smoke, in general, doesn’t smell good, and with good cause – our lungs crave clean oxygen and we have evolved to detect toxic smells the moment breathing air is contaminated. Cigarette smoke’s foul, persistent and insidious smell can remain in a couch, in the air and even on your skin and hair long after a smoker has stubbed out. So what’s in it? What are our senses warning us about?

Medical News Today contains a list of some of the ingredients of cigarette smoke, with the foreword: “Experts say that cigarette smoke contains over 4,000 different compounds. A significant number of them are toxic (poisonous) and can damage our cells. Many of them are carcinogenic (cause cancer).”

So what do these 4,000 compounds include? The list includes: Acrolein – commonly used in herbicides and polyester resins and also used in chemical warfare and as an ingredient in tear gas; Bensise, which is a common gasoline ingredient; Chromium, a common wood preservative; Lead; and unsurprisingly, Tar, described in the article as containing “several cancer-causing chemicals”.

Of course, you don’t need to read the full list of 4,000+ toxins in a cigarette. All you have to do is trust your nose, and its thousands of years of evolutionary experience.

The vaping alternative

For your sense of smell, and that of others around you it may be time for you to switch to e-cigarettes. As well as being an effective alternative to traditional smoking, scented vaping products can also enhance the experience further. Its variety of flavours can even work as an accompaniment or compliment to your meal.