Delhi's polluted air may put young hearts at risk, doctors warn 

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Delhi’s polluted air may be posing a risk to the cardiovascular health of young adults, with doctors warning that prolonged exposure to PM2.5, along with poor sleep, stress and physical inactivity, could add to existing heart-health risks.

A recent study conducted by researchers from across disciplines at University of Delhi’s Hindu College and Zakir Hussain College found that the capital’s average winter PM2.5 concentration was 269.35 micrograms per cubic metre nearly seven times the national standard and about 18 times of the WHO guideline cited in the study.

Nearly 98 per cent of the PM2.5 readings recorded during the study period exceeded the national standard, while levels crossed 700 micrograms per cubic metre in late December. The winter average was more than five times the levels recorded during summer and monsoon, the study findings — published in the ‘Frontiers in Sustainable Cities’ journal in March 2026 — said.

“Cardiovascular risk in younger adults cannot always be attributed to a single factor. Prolonged exposure to air pollution, inadequate or irregular sleep, chronic stress and physical inactivity can compound conventional risk factors such as hypertension, diabetes and high cholesterol,” said Dr Udgeath Dhir, principal director, Cardio Thoracic and Vascular Surgery, Fortis Gurugram.

Fine particles can promote vascular inflammation, oxidative stress and endothelial dysfunction, while poor sleep can disrupt blood pressure regulation and metabolic function, potentially increasing cardiovascular vulnerability, he said.

The University of Delhi study — conducted between October 17, 2023, and January 12, 2024 — used air-quality measurements and health-risk models to assess the potential impact of prolonged PM2.5 exposure among young adults. It projected a 1.65-fold increase in cardiopulmonary mortality risk under the prevailing annual exposure conditions.

The researchers, however, stressed that this was a model population-level estimate of long-term cardiovascular risks and did not mean that 1.65 times more young adults had developed heart disease or suffered heart attacks. The study estimated the potential health burden associated with exposure rather than following participants to record cardiovascular events.

The study found that PM2.5 exposure remained high beyond winters. The annual mean concentration recorded at the Central Pollution Control Board (CPCB) North Campus monitoring station in 2023 was 98.72 micrograms per cubic metre.

PM2.5 is particularly concerning because the micro-particles can enter the circulatory system. The study noted that exposure is associated with oxidative stress, systemic inflammation and cellular damage, which can contribute to cardiovascular as well as respiratory conditions.

For young adults, such exposure can continue for years before conventional cardiovascular diseases becomes clinically visible. The study noted that adolescents and young adults may be particularly vulnerable because of higher respiratory rates and ongoing physiological development.

Dr Dhir said young people should be cautious regarding exercise or physical exhaustion, particularly during periods of severe pollution.

“Not everybody is an athlete, and not every person needs an athlete’s level of training to have a healthy heart. Regular, moderate and appropriately progressed exercise is highly beneficial, but suddenly pushing an untrained body into long-distance running, marathon training or high-intensity workouts can place unnecessary and acute stress on the cardiovascular system,” he said.

“Exercise should be prescribed according to an individual’s age, fitness, medical history and conditioning — not according to social-media fitness trends or another person’s performance. The heart needs time to adapt to increasing workloads,” Dhir said.

The study logged the highest short-term exposure burden during winters. The mean winter-hazard quotient was calculated to 6.73 against the national reference concentration and 17.96 against the WHO parameter, both substantially above the safety threshold of one.

The researchers also found that 60.7 per cent of surveyed young adults reported worsening symptoms such as coughing, sneezing, shortness of breath or eye irritation during the highly polluted winter months, while 10.3 per cent reported respiratory conditions such as bronchitis or asthma.

They cautioned that these were self-reported observations and should not be treated as evidence of a direct individual exposure-response relationship.

Dr Dhir further said sleep health is increasingly relevant to cardiovascular risk, particularly in younger adults. Persistent snoring can sometimes be a marker of underlying disordered breathing during sleep and should not be ignored.

He said inadequate or irregular sleep could compound the effects of other cardiovascular risks. “Fine particulate matter can promote vascular inflammation, oxidative stress and endothelial dysfunction, while chronic sleep deprivation can disrupt blood-pressure regulation and metabolic function. These mechanisms may collectively increase cardiovascular vulnerability,” he said.

He advised young adults to get seven to nine hours of regular sleep, remain physically active, monitor blood pressure, blood sugar and cholesterol, and reduce exposure during severe pollution episodes. Dhir also cautioned against suddenly undertaking strenuous workouts, particularly when the body is not conditioned for them.

“The message is not to stop running or exercising; it is to exercise intelligently. Gradual progression, adequate recovery and recognising warning symptoms such as chest discomfort, unusual breathlessness, dizziness, fainting or palpitations are essential,” he added.

With World Heart Day being observed on September 29, doctors said cardiovascular health among young adults needs to be viewed beyond traditional risk factors, with air pollution, sleep, stress and physical activity also forming part of the broader picture.

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