Tuesday, October 3, 2023

Indoor air pollution: An overview

Indoor air pollution originates from different sources than the outdoor one. And most people don't know about them, keeping them unprepared to face that evil.

Executive Summary

Air pollution is becoming a serious problem. And, more and more data is getting published about its harmful effects.

Most of us read and worry about outdoor pollution. However, indoor pollution is worse because it involves outdoor polluted air and some more pollutants that are found only inside a household or an office cabin. Plus, indoor pollution is what you can do something about.

There are 3 types of pollutants in indoor air: physical, chemical and biological. All three of them need different technologies to remove them.

It is worth knowing this because your chances of death are 1% per decade, even if you are living in clean air (AQI = 50). The only solution is to breathe far cleaner air, whenever you can.

The article discusses these issues in more detail, and provides reference links for further reading.

In recent times, air pollution is becoming a more and more serious concern. We see images of polluted cities regularly on news channels. Research papers are emerging about medical conditions caused by air pollution.

Yet, all that dramatic part is only about outdoor pollution. Much worse is the indoor pollution, which is essentially outdoor pollution, plus some. And those additional sources are far worse than what we face outdoors.

Outdoor pollution

Worsening air quality

The quality of the air we breathe is slowly worsening. This is happening in most of the developing countries, such as India and Indonesia. Polluted air is also observed in some of the cities in the developed world. For example, Vienna and Paris have air quality that often crosses into ‘not–so–safe’ category.

Why are we noticing air pollution problems now?

Scientists are noticing more and more health problems arising from air pollution. There are three reasons for this:

Insufficient pollution data

In the past, not much data was available about air pollution worldwide. With healthcare costs rising due to air pollution, such air pollution data is now tracked in hundreds of countries. So, it is easier to draw conclusions.

Slow poison

Food pollution and water pollution show their effects within a few hours of exposure to polluted sources. However, air pollution is a slow poison. It takes years of exposure to air pollution to face significant health damage.

Of course, accidents such as the toxic gas leak in Bhopal, India in 1984 can kill thousands of people instantly. But, when we talk about the polluted air that we breathe day in and day out, it does not cause instant damage.

The damage rises with the level of pollution. The world was less polluted earlier. So, we did not notice such an increase in health problems in the past.

Masking of problems

Most of the air pollution–related problems are similar to what one gets even living in unpolluted air. For example, air pollution increases the chances of cancer, heart disease, diabetes, and stroke. These are common lifestyle ailments, even in the unpolluted world.

Ask anyone to guess what problems air pollution would cause. He would say: asthma, bronchitis, and pneumonia.

Most of us would not connect stroke and heart attacks to be caused by air pollution. But, one of the largest studies of any kind ever done on earth shows that stroke and heart attack are the two biggest fatalities caused by air pollution, ahead of COPD, respiratory problems, and lung cancer. The link downloads a pdf file from the WHO website.

Only way to figure this out is by taking the incidence of stroke in polluted areas, along with the average pollution in those areas, and compare it with the incidence of stroke in unpolluted areas. If the difference is statistically significant, we have a conclusion.

Indoor air pollution

When someone talks of air pollution, we think of a polluted chemical industrial zone, or toxic fumes blackening the sky. But, the real insidious pollution is what exists in your house and mine.

This is because the air inside our house looks quite clean. There is no noxious chemical smell, nor blackening ash that reduces visibility.

The reason why our indoor pollution is more dangerous is because we live in it. Most of us do not spend any time in chemical industrial zones at all. So that danger is quite far, unlike that in your bedroom air.

The indoor pollution is what you are breathing just now, as you are reading this article. By a billionth of a percentage every second, it is reducing your life. And, those of your loved ones in your house.

All this is even when the air pollution in your house is rated clean. Read on.

Chances of death due to air pollution

Incidentally, 32 years is one billion seconds. And, as per the World Health Organisation (W.H.O.), the chance your dying due to air pollution is about 0.3% in a decade. This is for the pollution levels considered safe (AQI = 50).

To understand these air pollution–related acronyms, such as AQI, various numbers, and their units, read an article on this website: Air pollution: various acronym, numbers, and units.

So, even if you are living in air which is rated safe for living, your chance of dying is 1% (≈ 0.3% x 3.2 decades) in one billion seconds. So your chance of dying increases by 1 billionth of a percentage every second you live in air which is borderline safe (AQI = 50).

Thus, I was not trying to be dramatic when I mentioned ‘one billionth of a percentage every second’.

Add to this, a similar chance of death for every family member in your house. After all, when you become obese and increase your chances of death due to obesity, your 20–year son faces no added risk. But, he breathes the same air as you do, in your house. So, he gets the same increase in his chances of death, as you do.

Thus, a family of four living even in ‘safe’ air (it will be much worse in an actually polluted air, when AQI > 50) will have a 1.2% chance of one of them dying in the coming decade, purely because of air pollution.

This is too high a risk to ignore. So, I would suggest you read this article and links to other air pollution–related articles on this website to understand the full scope of this issue. And then, take steps to protect your family from this modern evil.

And, before I forget, the percentages above are the chances calculated mainly for outdoor pollution. Add to that the indoor pollution, and the risk is even higher.

Components of air pollution

Broadly speaking, there are three types of air pollutants: physical, chemical, and biological.

Physical pollution

Physical pollution arises because of the physical characteristics of things in the air. For example, the particle size. Any particle below a certain size becomes dangerous because it can enter your lungs, and then your blood, reaching all organs of your body.

Chemical pollution

Chemical pollution arises because of the chemical nature of some things in the air. For example, chemicals in gaseous form are absorbed into your blood in your lungs. So, if the gases have harmful chemicals, they can lead to increased risk of illness and death.

Obvious household chemicals are disinfectants, nail polish removers, cooking gases, etc. However, there are certain dangerous gases that you may not know of. These are toxic gases emitted by your bed linen, furniture, curtains and other upholstery, wall paints, etc.

Since these are minuscule in quantity, the effect is not noticed easily. However, these days, with many air–conditioned rooms having windows kept closed for long periods, such as in summer or winter, the gases accumulate in the air.

Formaldehyde is one such dangerous gas. In the quantities that it is released into the air by indoor furniture, it is safe for inhalation every second; but dangerous for inhalation over months and years.

Biological pollution

Biological pollution arises due to bio–matter in the air. Examples are pollen, mildew, and spores of fungus in certain seasons.

If someone sneezes in your room, the virus will stay forever in your room, lurking somewhere. And, you have to hope that it does not get airborne at some later point.

In highly frequented rooms such as office spaces, showrooms, and aeroplanes, where too many people come and go, even a single person bringing in some viruses or bacteria will make the room contaminated. Since the air circulation in such places is a closed system, due to air–conditioning, the people in the room would get multiple exposures to the pathogens.

This bio–pollution problem is even more acute in medical places such as hospital, clinics, and biological research laboratories.

Technologies for air pollution removal

At the institutional and corporate level, there will be air pollution treatment plants that clean the air. They remove dust contaminants, scrub the air of chemical components, and use specialised ultraviolet chambers to decontaminate the air of living organisms.

There are various standards prescribed in the industry to specific grades of air cleanliness. For example, the air cleanliness required for a semiconductor fabrication clean room will be much higher than that needed in a hospital. However, hospitals have more stringer control over biological matter, which the clean rooms do not need to worry about.

Gadgets required for large volume cleaning, such as outdoor pollution removal, generally work on different technologies than those used for small area use, such as a household use.

I will mainly focus my other articles on household and office use, because most of us can control those. Removing air pollution of a city, neighbourhood, or even a large corporate office is not in hands of most of us; but we can certainly make a difference to our own air space.

Actionable tip

Use a good air purifier or air filtration system in the house.
Spend as much time as possible in unpolluted, filtered air in your house.

First published on: 24th July, 2019

Image credit: Vasilijus Bortnikas from Pixabay


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