New Delhi, one of the most polluted cities in the world, is not just unsafe outdoors, but also indoors.

But how unsafe is the indoor air in our homes, really? While global agencies peg indoor air with nearly 5x or 10x as much pollutants as outdoor air, BreatheEasy Consultants Pvt Ltd (BE) found different results as it conducted several studies on indoor air pollution for all types of homes located in various parts of Delhi-NCR.

The results of the study say this:

While outdoor air CO2 concentration mostly ranges between 400ppm to 450ppm in the Indian subcontinent, ISHRAE prescribes that CO2 concentration must never exceed 750ppm.

For CO2 concentration analysis, the study segregated the collected air quality data in 3 categories - Occupied Homes with Air Purification (doors/windows closed), Occupied Homes without Air Purification (doors/windows closed) and Occupied Homes without Air Purification (doors/windows open).

In Occupied Homes with Air Purification (doors/windows closed), the average CO2 concentration obtained was ~2400ppm and in Occupied Homes without Air Purification (doors/windows closed), the average CO2 concentration obtained was ~2380ppm. In both these cases there was no allowance of fresh air into the indoor spaces.

On the contrary, when data for Occupied Homes without Air Purification (doors/windows open) was analysed, the average CO2 concentration obtained was ~600ppm which is well within standard recommendation.

TVOCs: TVOCs concentrations in households result from odour from washroom and kitchen, usage of chemical cleaning solutions, adhesives, oil diffusers, deodorants, perfumes, mosquito repellents, off-gasing from carpet, paint, wooden furniture and home furnishings. It is also caused due to improper ventilation.

Average TVOCs concentrations observed in this study were higher than the ISHRAE prescribed limit of 200 µg/m3.

In homes where air fragrance sprays were used rigorously or mosquito repellents were constantly in use, TVOCs concentration exceeded even 1000 µg/m3

The study's authors make the following observations about the state of indoor air pollution in Delhi homes.

1. Marketing claims that indoor air is 10x worse than outdoors is ONLY partly true. The main pollutant that most common air purifiers tend to “improve”, is actually marginally better indoors than outdoors.
2. The pollutants that tend to be 5x – 10x worse indoors – CO2 (only when windows are closed) and TVOC’s, are NOT “removed” or “improved” by most common air purifiers.
3. Even with common air purifiers, PM2.5 levels are typically ABOVE the WHO annual safe exposure levels and TVOC levels are much higher than the standard
4. Carbon Dioxide (CO2) is a big pollutant that has gone unnoticed and has a big impact on quality of life
5. TVOCs can be managed dramatically with lifestyle choices in terms of materials used indoors and natural plants.