Besides other life threatening ailments, air pollution is literally making people fat; gain weight.
Number of obese people has almost trebled globally in past three decades and India is not far behind. Experts suggest that besides excess calorie intake, poor physical activity and genetic susceptibility, environmental pollutants are a major contributor to Indian’s weight gain; becoming fat.
Environmental pollutants are making us FAT
The hypothesis about ‘environmental pollution’ contributing to ‘people becoming fat’ was first highlighted at a 2001 multidisciplinary meeting held at Wisconsin, USA and the report was substantiated by the widely accepted article published in the Journal of Alternative and Complementary Medicine in 2002 by Paula Baillie-Hamilton.Her study was the follow up research of a 1970’s assessment that environment pollutants may be making people fat.
‘’Obesogens’ or ‘Endocrine disrupting chemicals’ are the main culprits for Weight Gain
‘’Obesogens’ or ‘Endocrine disrupting chemicals’ present in air, food and water have the potential to alter metabolic processes in the body. So far, 800 endocrine disrupting chemicals have been identified, but only a small fraction of these have been studied,”… Sneha Limaye.
Among these obesogens Indians usually encounter PM 2.5, the most potent obesogen generated from combustion emissions such as automobile exhaust. It can reach various organs of body and trigger a host of diseases including asthma, bronchitis, cancer, cerebrovascular diseases, Type II diabetes mellitus and Obesity.
Delhi is the most PM2.5 saturated city in the World
180 cities in India have fine particulate matter (PM2.5) six times more than the permissible limit set by WHO. As revealed by India’s central pollution control board recent data, Delhi has world’s highest annual average concentration of PM2.5.
PM2.5 damages Health
Thrombosis and atherosclerotic lesion. Experiments with animal models suggest plausible mechanisms by which PM exposure could cause series of metabolic disorders. Studies have shown that 6 months exposure to pm2.5 leads to thrombosis and formation of atherosclerotic lesion (fat deposition in blood vessels).
Type II Diabetes Mellitus. This PM2.5 can spread to other organs once they appear in blood and respiratory circulation. It causes insulin resistance i.e. body become less sensitive to insulin (hormone responsible for glucose metabolism) thus causing type II diabetes mellitus.
Insulin resistance. Insulin resistance is triggered by inflammation of adipose (fat) tissue. Adipocytes are a major endocrine gland that play important role in appetite regulation and energy hemostasis, thereby causes whole body insulin resistance.
Weight gain and Autoimmune diseases. PM2.5 induces obesity via alteration in weight controlling hormones, alteration in sensitivity to neurotransmitters or by alteration in activity of sympathetic nervous system.
However, the exact mechanism is not fully understood. Further, it produces inflammatory byproduct cytokines which trigger immune cells to invade otherwise healthy tissues (autoimmune diseases).
Such systemic response could provide explanation of the effect of inhaled pollutant is not only bound to lungs only.
A few of the Research findings
1. Extensive research in both humans and animals demonstrate the adverse impact of continuous exposure of PM2.5. In a study by Qinghua sun at Ohio state university, laboratory mice were kept in different atmospheric conditions for 10 weeks. The mice, which were exposed to air pollution, showed greater body fat deposition both around the belly as well as around the internal organs.
2. Corresponding human data is also in agreement. ”Children born to mothers who smoked during pregnancy have 50-80% greater risk of being obese or overweight,’’ said researcher Sneha Limaye of chest research foundation (CRF) chest physician and director of CRF Sundeep Salvi has published an article in Immunology and Allergy clinics of North America, 2014 where he has gathered evidence from globally published literature to suggest that air pollution play a key role in causing obesity among adults and children.
3. In 2015, Abby fleish, from Harvard Medical School has published an article where she has described that in first six months, babies of mothers in polluted areas appear to put on more weight more than those in cleaner areas.
4. In 2016, Robert Brook et al, provide important global public health warnings that “air pollution may pose a risk to cardiometabolic health even at the extremely high concentrations faced by billions of people in the developing world today”. He and his colleagues in china found that problems like insulin resistance and hypertension peaked whenever smog descends in city, in two year retrospective study-providing more concrete evidence.
Extensive work is already going on globally to find the missing links to fill gaps in our knowledge. Sooner or later these missing links will be proven, but how concerned should we be? Scientists stress that although short-term risk is minimal, it should not be used as a precursor for obesity by itself, without considering other aspects of your lifestyle. But a great number of people are living in areas with high pollution; over the long term mortality is going to increase.
The solutions are familiar, but difficult to implement
1. The first and foremost option is to restrict traffic pollution by promoting battery-operated and low emission vehicles.
2. Replacing private vehicles with comfortable public transport should be the priority for city planners in growing cities like Delhi.
3. Streets could also be redesigned to reduce the exposure to pedestrians and cyclists.
4. As an immediate measure, air purifiers can be added to more homes, schools and offices to filter out some of the harmful particles.
Chandra Venkataraman from the Indian institute of Bombay, in Mumbai warned “despite proposed emission control there is significant growth in demand for electricity as well as industrial production, so by 2050, this growth will lead to an increase in future air pollution in India”.