‘Leaky’ urban homes can’t keep pollution out: Study

Ahmedabad: As residents of Bodakdev prepared for bed around 10pm, their air quality monitors revealed something unsettling: PM 2.5 levels climbed to 61 µg/m3 (micrograms per cubic metre) — more than 50% above the safe threshold of 40. Meanwhile, PM 10 levels soared to 153 µg/m3, nearly triple the acceptable limit of 60. We often think of our homes as safe havens, shielding us from the hustle and bustle and the pollution of the outside world. But what if researchers told you that your home might not be as airtight as you think? And what if that lack of airtightness was actually contributing to the poor air quality you're trying to escape?
Buildings or apartments have inevitable openings, whether they're intentional (like doors and windows) or accidental (near the joints of walls, floors, and windows). These openings let air in and out. A unique experiment, the "blower door test", was carried out to find out how leaky a building envelope is. It was conducted in 20 apartments in Ahmedabad and Delhi between 2021 and 2023 by researchers from IIT Roorkee and Shri Mata Vaishno Devi University, helping to understand how outdoor pollution seeps into our homes.
"The results showed that the buildings had an infiltration range of 0.53 to 1.63 air changes per hour (ACH). ACH is a measure of how many times the air inside a room or building is replaced by outside air in an hour," state researchers Atul Anand Jha and Prabhjot Chani from IIT Roorkee and Anoop Sharma of Shri Mata Vaishno Devi University. This data was then used to calculate the Effective Leakage Area (ELA). The ELA is a hypothetical measurement representing the total area of holes that air is flowing through.
"Most of the residences in the study had a normalised ELA between 2-4cm per square metre of exposed wall surface area. During winter (Nov to Jan), the study states, air quality often falls into ‘poor' to ‘severe' categories due to low temperatures and still winds, which keep pollutants suspended longer. The main culprit is particulate matter, especially PM10 — inhalable particles with diameters of 10 micrometres and smaller. These pose serious risks, making it crucial to understand how they travel indoors.