Why the air inside our homes and offices can be more dangerous than what we’re breathing outside

“Stay indoors.”

This is the most common advice dispensed by both governments and news channels every time air pollution reaches hazardous levels in our cities in late autumn.

If you live in an Indian city, the outdoor pollution is often so tangible that you can almost touch it with your fingers. When you’re walking down a busy street, with your nose and mouth covered to protect you from vehicular fumes, sometimes even wearing a mask during the winter, you often quicken your pace to make it back to your homes or offices because that’s where you know you’ll be safer.

Staying indoors when outside air is poor is good advice if you have an excellent air purifying solution at home. But if you don’t have an air purifying system, simply being indoors doesn’t ensure your safety. Hoping to protect yourself from outdoor air by shutting all doors and windows doesn’t work. And there’s a good reason for it. The air inside our homes and offices is as or more dangerous than outside air. It’s another aspect of air pollution that we have to contend with.

So why is indoor air more polluted?

There are two parts that make up indoor air. One is the outside air that is constantly moving into our homes, and the other is the air indoors. Both components have their own share of pollutants. We know the major pollutants of outside air: PM, carbon dioxide, ozone, nitrogen oxide and sulphur oxide. But indoor air also has its own particular breed of pollutants that most of us aren’t aware of.

What are the toxins inside our homes that make air bad? To understand this, I’ll dissect the air inside your home and show you the different elements. Indoor air is a combination of VOCs, mould, pollen dust, fumes from varnishes and paint, pet hair, smoke from candles and agarbattis, inks and, of course, the carbon dioxide we breathe out constantly.

These toxins, combined with the polluted outside air – which moves freely through all indoor spaces – compounds the toxicity levels. Knowing this can make you look at your home with a new perspective. Most Indian homes, when not cleaned, protected and sealed properly, are often more polluted than the traffic-riddled, dust-clouded, dirty cities we live in.

Did you ever think your sofa or the carpet in your living room could be polluting the air in your home? Probably not. But the truth is they do.

When outdoor air comes into our homes bringing in harmful PM and other gases, it combines with the indoor carbon dioxide and VOCs to create a beast of a problem.

Indoor air pollution is actually more complex because not only are we dealing with outdoor air pollution seeping in but it is compounded by the fact that everything inside our homes pollutes the air in any case. Even in a country like Switzerland which has very clean air, there is indoor pollution. With a critical difference: their outside air is much cleaner than ours. So all they need to do is open their windows and doors to let in fresh air that can sweep through the house and carry out harmful gases.

So what are VOCs?

To understand this, we need to go back to a little bit of physics. Don’t worry; I’m not going to bore you with lessons. Just keep in mind: the world is in constant motion. What this means is that the world around us is in a constant state of flux. From a macro point of view, this means the sun shines, the earth revolves around the sun, the earth rotates on its axis, there is day and there is night, there are seasons. Every wave in the ocean is different.

Then there are the other, smaller changes, which we can observe, sense and feel. We grow taller, we grow older, our skin sheds, our nails regrow, we lose our teeth, and we gain some, our organs degenerate.

There is a third kind of change, a subtler one, that occurs at the molecular level. All matter – solid, liquid and gas – is made up of tiny particles called atoms that join to form molecules. And these atoms are changing state every moment. This is the Kinetic Theory of Matter. By this principle, everything you own in your home – tables, chairs, cutlery, books, the television, clothes, paper, electronics, just about everything, is in a constant state of flux. And a by-product of this transformation are gases. The bed you’re lounging in right now is releasing a gas. This gas is called a volatile organic compound or VOC – a natural by-product of the maxim of change.

Not all gases released by our beloved things at home are toxic. If the objects are made from green-friendly substances then they are not.

I once measured the levels of VOCs inside my house and this was what I found. In an ordinary bedroom with closed windows and doors and two people sleeping, the next morning these were the results: PM was equal to that in outside air or 20 to 30 per cent less than in outside air, sulphur and nitrogen oxide were equal to or 10 to 15 per cent lower than in outside air. When the indoor carbon dioxide level was 2500 ppm, the outside air had a carbon dioxide reading of 400 ppm. High carbon dioxide levels are always a good indicator of high VOCs in the room.

VOCs are ten times higher in a closed room. But this does not mean that outside air is not dangerous. What I’m trying to explain is that both types of air (outdoor and indoor) have their fair share of pollutants. Of course, outside air has the most dangerous pollutants. But since we spend more time indoors, we also need to examine the pollutants there.

Excerpted with permission from How To Grow Fresh Air, Kamal Meattle and Barun Aggarwal, Juggernaut.