Daijiworld Media Network - New Delhi

New Delhi, Sep 2: In a groundbreaking study conducted by the Bose Institute under India’s Department of Science and Technology, researchers have found that airborne pathogens—bacteria capable of triggering respiratory, gut, oral, and skin infections—are present in twice the concentration in densely populated urban areas compared to less crowded regions. The study, which focused on Delhi as a representative urban metropolis, was published in the international journal Atmospheric Environment: X.

The culprit behind this bacterial boom is PM2.5—tiny pollutant particles that dominate the city’s air. These microscopic particles act as efficient carriers for pathogenic bacteria, allowing them to travel deep into the human body via inhalation. Dr. Sanat Kumar Das, who led the research, emphasized that PM2.5 particles "hitch bacteria a ride" through the city’s air, making them more dangerous due to their ability to penetrate deep into lung tissue.

Delhi, situated in the Indo-Gangetic Plain, already ranks among the world’s most polluted and densely populated regions. The study observed that the combination of high pollution levels, dense population, and seasonal weather patterns—particularly during winter—creates ideal conditions for airborne bacteria to survive and spread. With winter comes western disturbances that lower temperatures and increase humidity, causing stagnant air and trapping pollutants close to the ground. This environment acts as an incubator for airborne microbes, particularly during hazy days or winter rains.

While previous research has noted higher microbial populations in the Indo-Gangetic region during winter, this study fills a crucial gap by connecting the dots between weather, pollution, and population density to bacterial health risks. The researchers warned that this dynamic mix significantly raises the odds of infection and could increase the likelihood of outbreaks in major cities.

Calling the findings a potential “wake-up call for urban health planning,” the team highlighted the urgent need for integrated approaches that combine meteorology, pollution control, urban design, and healthcare strategies. In megacities like Delhi, where millions already grapple with toxic air, residents might also be unknowingly exposed to invisible bacterial threats. Understanding this airborne bacterial ecosystem could become crucial for early disease surveillance, public health interventions, and smarter city planning in the face of rising urbanisation.