Each cigarette smoked a day by heavier smokers may increase the risk of contracting diseases such as respiratory disorders, cancers and cardiovascular ailments by more than 30 per cent, according to a study.
The study by researchers links heavier smoking with 28 separate health conditions, revealing a 17-fold increase in emphysema, 8-fold increase in atherosclerosis or clogged arteries and a 6.5-fold higher incidence of lung cancer.
Light smokers on average smoke less than 10 cigarettes a day, moderate smokers 10 to 19 cigarettes a day, and 20 or more cigarettes a day is classified as heavy smoking, they said. The findings, published in the journal EClinicalMedicine, analysed hospital data and mortality statistics from more than 152,483 smokers in the UK Biobank to look how heavier smoking affects disease risks.
The risk of suffering respiratory diseases, cancers and cardiovascular diseases increased with each cigarette smoked per day, the researchers said. The links between heavier smoking and emphysema, heart disease, pneumonia and respiratory cancers were particularly high.
However, the researchers also found associations with many other respiratory diseases, renal failure, septicaemia, eye disorders, and complications of surgery or medical procedures. "Tobacco smoking is the leading preventable cause of death worldwide and smokers typically die 10 years earlier than non-smokers," said UniSA Professor Elina Hypponen.
"Despite a global decline in smoking over the last 20 years, an estimated 20 per cent of the world's population aged over 15 years are still smoking tobacco," Hypponen said. Several known smoking outcomes, including stroke, were not identified in the study, which only counted cases above 200 for each health condition, the researchers said.
"We only looked at how heavier smoking further affects disease risks in a group of people who are all at least past smokers, so compared to never smokers, the health effects are going to be even more notable. "Other factors, including when people start smoking or how long they have smoked, may also affect the health consequences arising from smoking," Hypponen said.