Water sprinkler set in the streetlights pole at ITO, to contain pollution, at New Delhi. (Source: Express Archives)Not just your lungs, high levels of air pollution may be damaging your kidneys too. Researchers found that increases in exposure to PM2.5 were linked with reduced filtration efficiency of the kidneys, according to results of a study that followed over 12,000 people for six to ten years. The findings were recently published in the journal Kidney International Reports. This decline was evident even when the researchers controlled for other risk factors such as diabetes and hypertension.“This is a part of an ongoing series of studies that looks at the impact of air pollution on different diseases. So far, we have shown an association with higher air pollution levels and increased risk of hypertension, diabetes and dyslipidemia (high levels of blood fats like cholesterol and triglycerides). Now, we have shown that it impacts kidney function as well. And, the association remained consistent even after controlling for other factors, meaning the impact of air pollution on kidneys is not through the increases in diabetes and hypertension, but independently as well,” says Dr V Mohan, one of the authors of the study and chairperson of Dr Mohan’s Diabetes Specialties Centre, Chennai.The participants were from Delhi and Chennai — two cities with very different levels of ambient air pollution. “The findings show that long-term exposure to fine air pollution may gradually reduce kidney function even in younger adults who do not already have chronic kidney disease (CKD),” adds Dr Mohan.First, what did the study find?The PM2.5 levels in Delhi were much higher than Chennai during all three hospital visits by the participants during the study. The baseline PM2.5 level in Chennai stood at 33 μg/m3 and in Delhi 118 μg/m3. The levels stood at 37μg/m3 and 30 μg/m3 for Chennai during the subsequent visits and 123 μg/m3 and 130 μg/m3 for Delhi.The doctors measured the estimated glomerular filtration rates (eGFR) — used to check the health of the kidney — and found it to be 112 mL/min/1.73 m2 for the Chennai residents and 106.4 for Delhi residents. While both values are considered to be normal, people in Delhi were already starting with lower reserves.The decline was also sharper. The study found that every 5 μg/m3 increase in annual average PM2.5 levels led to a decline of kidney function by 0.42 in Delhi residents and 0.32 in Chennai residents.“The study clearly shows that an increase in PM2.5 exposure is linked with worsening kidney function. There could be as much as 4% decline in a year. We know that kidney function goes down with age, but if you start with lower reserves, the damage with age would be quicker,” says Dr Dorairaj Prabhakaran, one of the authors and executive director of Centre for Chronic Disease Control.Story continues below this adWhy is this significant?There are 143 million people who live with chronic kidney disease in India. And they live in places with some of the highest PM2.5 exposure in the world. “While we know of the impact of high pollution levels on the respiratory system, this adds to the evidence on the impact of the particulate matter on other organs as well. This provides further stimulus for policies to address air pollution,” says Dr Mohan. Controlling diabetes, hypertension, and obesity is as important as taking care of this environmental factor in reducing levels of chronic kidney disease in India.How does pollution impact the kidneys?Doctors say that there may be several ways in which PM2.5 may be affecting the kidneys. This includes chronic systemic inflammation, oxidative stress leading to cell damage, dysfunction of the lining of the blood vessels, damage to the tiny blood vessels, and the small particles directly going into the blood circulation and thereby the kidneys. “These may be the possible ways in which the kidney is being damaged by air pollution,” says Dr Mohan.What needs to be done?There is a need to curb air pollution. Dr Prabhakaran says, “This also means that there is an urgent need to address air pollution levels in places such as Delhi. In the meantime, people can protect themselves by donning N-95 masks when they go for their morning walks. Air purifiers are also a good idea. But, of course, overall policy measures to address pollution levels are needed.”While masking up may be the short-term measure, Dr Mohan says reducing pollution levels is possible through public action as seen in other places across the world. He says: “It is not impossible. A couple of decades back, Los Angeles was probably as polluted as Delhi but they identified the problem areas and worked on it. People were involved and now the LA skies are clear. Take the example of Indore, if they are able to maintain a clean city year after year, action can be taken through similar mechanisms to curb pollution as well.”Anonna Dutt is a Principal Correspondent who writes primarily on health at the Indian Express. She reports on myriad topics ranging from the growing burden of non-communicable diseases such as diabetes and hypertension to the problems with pervasive infectious conditions. She reported on the government’s management of the Covid-19 pandemic and closely followed the vaccination programme. Her stories have resulted in the city government investing in high-end tests for the poor and acknowledging errors in their official reports. Dutt also takes a keen interest in the country’s space programme and has written on key missions like Chandrayaan 2 and 3, Aditya L1, and Gaganyaan. She was among the first batch of eleven media fellows with RBM Partnership to End Malaria. She was also selected to participate in the short-term programme on early childhood reporting at Columbia University’s Dart Centre. Dutt has a Bachelor’s Degree from the Symbiosis Institute of Media and Communication, Pune and a PG Diploma from the Asian College of Journalism, Chennai. She started her reporting career with the Hindustan Times. When not at work, she tries to appease the Duolingo owl with her French skills and sometimes takes to the dance floor. ... Read More Tags:air pollutionkidney