Air pollution linked with cardiovascular diseases

Air pollution is emerging as one of the main risk factors for cardiovascular deaths in developing countries, according to a new study.

A large proportion of cardiovascular disease events and mortality can be attributed to a small number of modifiable risk factors. This cohort study has been carried out in 21 countries where the researchers have examined 14 modifiable risk factors.

Approximately 70% of cardiovascular disease cases and deaths in the overall study population were attributed to modifiable risk factors. The modifiable risk factors are tobacco use, alcohol, diet, physical activity and sodium intake. Metabolic factors include lipids, blood pressure, diabetes and obesity. Socioeconomic factors included are education, symptoms of depression, besides household and ambient pollution.

The study highlighted the importance of addressing both household and ambient air pollution to reduce cardiovascular disease and death. “In the middle-income and low-income countries exposure to both forms of air pollution is high. Ambient air pollution is primarily associated with a higher risk of cardiovascular disease, while indoor air pollution is strongly associated with a higher risk of death,” said Dr Manmeet Kaur, Post Graduate Institute of Medical Education and Research, Chandigarh while speaking with India Science Wire.

"Several risk factors such as low education and indoor and outdoor air pollution that were underappreciated in the past have turned out to be more important than others,” said Philip Joseph, a joint lead author of the paper.

The study included four high-income countries, twelve middle-income countries and five low-income countries. In the study, the researchers examined associations of 14 modifiable risk factors with mortality and cardiovascular disease of 155,722 participants without a prior history of cardiovascular disease. Out of these participants, 35,793 were from India.

“In developing countries women are more prone to cardiovascular diseases than men, as being at home they encounter indoor pollution more than men. The particulate matter is found to be more indoors” said Prof V R Kutty (Health Action by People, Trivandrum).

The study also points out that among the behavioural risk factors, tobacco had the strongest association with cardiovascular disease, followed by physical inactivity and low-quality diet. Of the metabolic risk factors, hypertension was strongly associated with cardiovascular disease followed by diabetes, elevated non-HDL (High- Density Lipoprotein) cholesterol and increased waist-to-hip ratio. Other important factors that are associated with a higher risk of cardiovascular disease like low education levels, symptoms of depression, low grip strength and household pollution.

The study also says that in high-income countries the risk of cardiovascular diseases is highly associated with tobacco whereas in low-income countries, the risk was highest with low education levels. And the risk associated with diabetes was highest in high-income countries and low-income countries both.

The research paper has been published in the journal The Lancet and the research was led by researchers of the Population Health Research Institute (PHRI) of McMaster University and Hamilton Health Sciences in Hamilton, Canada.

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(India Science Wire)