Air inside Delhi homes as harmful as outdoors: Study

Long term exposure to high fungal and bacterial concentrations make indoor air in several parts of Delhi almost as harmful as the smog outside

- PRESS TRUST OF INDIA

As Delhi braces for winters and likely another spell of the late fall smog, a study has found that the air inside city homes are filled with fungal spores 12 times higher than the WHO safety limit, causing skin allergies, respiratory issues as well as anxiety among residents.

The study by Delhi University’s Satyawati College, Jamia Millia Islamia and US's South Dakota State University, has also revealed that the bacterial levels were recorded to be 10 fold higher than the World Health Organization (WHO) safety limits.

Long term exposure to high fungal and bacterial concentrations make indoor air in several parts of Delhi almost as harmful as the smog outside, noted the study published in Frontiers in Public Health, 2025.

The study also noted that most fungal particles were smaller than 2.5 microns, small enough to penetrate deep into the lungs and cause lasting respiratory damage.

It observed a clear seasonal pattern. Fungal levels rose steadily from winter and reached their highest concentration at around 6,050 CFU per cubic metre in fall between September and November -- the period just before Delhi’s smog sets in.

Bacterial levels increased from winter to summer, peaking in August, before declining in fall, it said.