Second-hand smoking may increase asthma risk: study

Second-hand smoking may increase asthma risk: study

Countries with higher male smoking rates such as India and Bangladesh may develop higher asthma and wheezing rates as a result of more exposure to second-hand smoke, scientists say.

Underweight and obese women who also drink alcohol and smoke tobacco have a two-fold higher risk of being diagnosed with asthma than women with a healthy body mass index who do not drink or smoke, a new study has found.

Women with low and high body mass indexes, or BMIs, who smoked and drank were also two to three times more likely to experience wheezing, the study found.

Asthma is a respiratory condition where spasms in the air pathways of the lungs cause difficulty breathing; usually triggered by an allergy or sensitivity in the environment.

Asthma is a global health priority due to the extent and duration of disability, affecting 334 million people worldwide, researchers said.

The study, published in BMJ Open Respiratory Research, is the first to assess the combined effects of BMI, smoking, drinking alcohol and solid fuel use on asthma risk.

The study included data gathered between 2002 and 2004 from about 175,000 people aged 18 to 44, across 51 countries.

“Although individual physical and behavioural factors associated with asthma have been examined before, people are often exposed to multiple risk factors so it’s important we understand the combined impact,” said Dr Jayadeep Patra, lead author of the study and an epidemiologist at the Centre for Global Health Research of St Michael’s Hospital in Canada.

“Our research found overall increased risk for wheezing and asthma in both men and women, but the magnitude of the combined effects from low or high BMI, smoking and drinking was consistently higher among women than men,” said Patra.

Men showed higher prevalence of smoking and use of alcohol than women, but more women had unhealthy BMIs (underweight or obese) than men, highlighting the greater impact of female BMI as a risk factor.

Patra also noted there are significant variations in diagnosed asthma between countries, with increasing rates found in low-income and middle-income countries, potentially because of higher exposure to multiple risk factors, including the use of solid fuel.

In low and middle-income countries, solid fuels such as dung, charcoal or wood are used for cooking and are common in many households.

These fuels are known to contribute to higher risk of developing respiratory and cardiovascular disease, compared to individuals who cook with gas or electric devices.

Patra said the combined effects of identified risk factors have not been sufficiently studied as of yet, with many questions still unanswered.

For example, exposure to air pollution or second-hand smoke in lower income countries could contribute to higher rates of asthma and respiratory issues.

“Countries with higher male smoking rates such as India or Bangladesh could effect on higher asthma and wheezing rates as a result of more exposure to second-hand smoke,” Patra said.