Since 1987, the member states of the World Health Organisation (WHO) on 31 May of every year celebrate the World No Tobacco Day.
Why do we do so? The prime intention is to draw global attention to the tobacco epidemic and the preventable death and disease it causes.
This article is intended to give an overview of the beginnings of tobacco, the relation between smoking and public health and the advances in research from the chemistry perspective with focus on the indoor environment.
The history of smoking dates back to 5000–3000 BCE, when the agricultural product began to be cultivated in Mesoamerica and South America. The initial burning of the tobacco plant substance either by accident or to explore other means of consumption marked the first exposure to tobacco smoke. Smoking in the Americas was generally associated with the incense-burning ceremonies of shamans but later was embraced for pleasure or in a social context. Tobacco smoking and various hallucinogenic drugs were used to achieve trances and to come into contact with the spirit world. In 1560, Jean Nicot de Villemain, introduced tobacco in Europe when he sent tobacco and seeds to the French King who promoted its medicinal use. At the time smoking was believed to protect against illness, in particular against the plague.
By the mid-17th century, most major civilisations had already assimilated the use of tobacco into the native culture, despite some occasional attempts to control its use. Anti-smoking groups were active in Germany already around 1912, however in the 20th century, smoking was common through social events favouring and promoting the use through a “smoke night”. From 1950 onwards, the first studies associating tobacco smoking with lung cancer were published. The British Doctors Study, initiated in 1951 and the United States Surgeon General’s Report on Smoking and Health in 1964, were two pioneering studies that have shown the link between smoking and cancer. Scientific evidence supporting these claims increased substantially in the 1980s.
Fast forward 40 years ... where do we stand?
At least 1.3 billion people worldwide use some form of tobacco.
Although the global prevalence of daily smoking has decreased, the absolute number of smokers has increased. About 6 trillion cigarettes were smoked worldwide in 2016. From the knowledge of particulate matter and nicotine emission rates, conservatively, during tobacco smoking worldwide, releases about 22 million kilograms of nicotine and about 135 million kilograms of particulate matter into the atmosphere each year.
By 2013, the total number of deaths worldwide attributable to passive use was approximately 6 million (1%). Tobacco use remains a significant health concern because it is the leading global cause of preventable death, with 450 million deaths projected in the next few decades. Approximately 90% of lung cancer mortality in populations with prolonged use is attributed to cigarette smoking and more than 3000 people in the world succumb to this deadly and relatively incurable disease daily. Lower respiratory infections in children younger than 5 years, ischaemic heart disease in adults, and asthma in adults and children indicate there is no risk-free level of exposure to Second Hand Smoke (SHS) or passive smoke. The European Environment Agency, supports the evidence that tobacco smoking in the indoor environment has always been the most important and significant contributor to indoor particulate matter and thus to a poor indoor air quality.
Nicotine, the principal chemical that is responsible for the addiction to cigarette smoking has been widely researched in the last four decades. Its behavior and characteristics in the exhaled smoke, together with the smouldering cigarette fumes, collectively termed as passive smoke or SHS, were studied carefully in controlled and indoor environments such as homes, offices and leisure places.
Throughout these years, through very expensive clinical studies carried out all around the globe we have a clear understanding of the compounds of nicotine inside our body and how they behave. We know with statistical certainty that the abovementioned health effects associated with tobacco smoke are devastating and a lot of effort and money have been and is being spent to curb this habit.
At first glance, it appears that the knowledge about passive smoking has been acquired and its effects have been well understood. Through targeted educational campaigns and a regulatory framework encouraged by the WHO that supports smoke-free environments in many public and indoor places, one hoped for a real change and a drastic reduction in tobacco smoking. Unfortunately it does not seem the case where even in Malta, although a decrease in the smoking prevalence occurred over the years, it is not as low as one wishes. According to the 6th Edition of the Tobacco Atlas published by the The American Cancer Society in 2018, in Malta, 23.5% of adult males and 13.7% of adult females (age 15+), 2.5% of boys and 3.0% of girls (10-14 years) use tobacco daily. Apart from the adult males, the other categories smoke more than the average in the very high human development index countries.
When it comes to deaths, 19% of males and 5% of females died because of tobacco. In both cases the levels are lower than the average in the very high human development index countries. This index goes beyond the income considerations but incorporates additional critical indicators such as health and education.
Especially in the United States, through the Third Hand Smoke (THS) research consortium of the University of California substantial funding is now being devoted to research on the potentially more dangerous THS. This is defined as the peril looming around us after a cigarette is extinguished! Smoking outside or smoking in a balcony or a yard, especially when children are around is enough? Are risks due to exposure eliminated by smoking outdoors? Not smoking in an enclosed environment reduces the risks of exposure but certainly does not eliminate them.
The fact that nicotine is extremely sticky to any surface, its presence on the clothes and our body makes it inevitable to be found indoors.
Nicotine is found even in non-smokers’ houses, whilst in smokers’ houses it is typically thousand times higher. Over time, the smoke particles and nicotine on surfaces are exposed to further reactions.
Most Tobacco Specific Nitrosamines (TSNAs) are formed in tobacco during the post-harvest period, while a number are produced when a cigarette is burned. Way back in 1978 it was shown that three main TSNAs are formed in the reaction of nicotine and gaseous nitrous acid, namely, NNA, NNK and NNN. Due to its reactivity and instability at high temperatures during tobacco pyrolysis, NNA has not been reported previously in the atmosphere. However, NNK and NNN, both potent carcinogens, are known to be the most abundant in tobacco smoke particles, others like NAT and NAB are also present. Evidence is mounting to support the role of TSNAs important causative factors for cancers of the lung, pancreas, esophagus, and oral cavity in people who use tobacco products.
In the last decade the mechanism of the atmospheric production of TSNAs was outlined. It appears that the formation of TSNAs outdoors is hindered by sunlight, however in a landmark study by Dr Aquilina et al in 2021, a tobacco smoke particulate matter marker has been identified, indicating also that TSNAs are ubiquitously present in fine particulate matter. We cannot choose not to breathe, thus a possible chronic exposure to TSNAs by the inhalation pathway cannot be ignored, even for non-smokers.
The dominant source of indoor particulate matter is cooking and others such as incense and candle burning, gas heating, wood burning in fireplaces, use of air fresheners, vacuum cleaning and wet cleaning contribute to a complex environment. From an atmospheric chemistry point of view the level of scientific understanding is still on the low side.
However adding up to the abovementioned sources, when smoking occurs indoors, apart from the enormous production of fine particulate matter that includes a myriad of combustion driven compounds such as polycyclic aromatic hydrocarbons, a suite of compounds that is equally carcinogenic, as tobacco smoke ages, within a few hours TSNAs form. Their concentration indoors could be appreciable because TSNAs and nitrous acid are less susceptible to photochemical decomposition. Furthermore the deposition of particulate matter over time in the indoor environment, especially in reduced ventilation will land the TSNAs all over the place. A case in point are carpets and rugs favour the accumulation of TSNAs in our houses. Before we wash the floors, the particulate matter will be re-suspended in air every time we walk around or dry sweep the floors. We will continue to breathe this plume for the whole period we are indoors. It has been shown that although they are called air purifiers, their use does not really clean the air of nicotine or the TSNAs. If the indoor spaces are not adequately ventilated the TSNAs increase in concentration over weeks. This leads to a very important health consideration. Apart from inhaling indoor particulate matter, young children in our homes hang around on floors and carpets and tend to touch surfaces and ingest particulate matter through floor-to-mouth touching. This implies that the exposure to TSNAs would be higher in children and thus the cancer risk is higher.
Several scientific issues are still unanswered however. The main concern is associated with the intake dose of TSNAs by children and how it effects their long-term risk for various cancers. Dr Noel Aquilina and few other scientists in Europe teamed up with the THS consortium to advance our understanding.
For the World No Tobacco Day 2021, the WHO’s motto is Commit to Quit.
Quoting the WHO, the benefits of quitting tobacco are almost immediate. After just 20 minutes of quitting smoking, your heart rate drops. Within 12 hours, the carbon monoxide level in your blood drops to normal. Within 2-12 weeks, your circulation improves and lung function increases. Within 1-9 months, coughing and shortness of breath decrease. Within 5-15 years, your stroke risk is reduced to that of a non-smoker. Within 10 years, your lung cancer death rate is about half that of a smoker. Within 15 years, your risk of heart disease is that of a non-smoker. Is that enough to give everyone a nice health gift especially to our children?