Saturday, June 13, 2009

Cigarettes & Indoor Air Pollution

Hello World! This is Govindraj Umarji. Dr. Sunita has invited me to write a post for A Greener You. I am really glad to be a part of this initiative.

A few bits about me: My basic degree is in Chemical Engineering. I completed my Masters under the guidance of Professor Patil (CESE 2007 Batch), with the topic being Improvement of the Indoor Micro-environment in Commercial Kitchens. Dr. Sunita & I share our Guide, Professor Patil and a passion for topics relating to Indoor Air Pollution. All right, then. On to my post.

These days, we hear a lot about indoor air pollution and its effect on human health. But what exactly is indoor air pollution? What are the sources of indoor air pollution? Why does it occur in the first place? Well, this post will try to provide some insights on that. Indoor air pollution is an area that is close to my heart and you will hear more on IAP on this blog from me.

To start with, let me get to pollution in general. Contrary to popular belief, a pollutant is defined as a substance present in excess of its normal concentration in the environment. That means, any substance on this earth has a the potential to be a pollutant, if it is in the wrong place at the wrong time. Air pollution is a serious issue because unlike water and land pollution, physical boundaries are not sufficient to contain it. Pollution, in that sense, is a unifying factor across national and international boundaries! Consider the case in point: rapid industrialization in Germany and France led to Sweden’s lakes turning acidic due to acid rain! Now, that is what they mean when they say that the world is getting closer.

Another myth is that CO2 is a pollutant. CO2 is a green house gas and is not a pollutant. CO2 will be called a pollutant if it is present in amounts exceeding 5000 ppm and since there are a lot many sinks to this particular gas, there is scant possibility of this gas making it to that high a concentration. Anyway, coming back to the point at hand, we all know what ambient air pollution is. There are standards set by the Central Pollution Control Board [CPCB] which are known as National Ambient Air Quality Standards [NAAQS]. More information can be found at the website:

However, there are no standards prescribed for the indoor environment. Why is this so?Consider the fact that there are at least a million registered and un-registered architects all over the world and each one has her / his own way of designing buildings. Each one gives different weightage to lighting and ventilation factors. Ergo, it becomes difficult to gauge how much air is going into an indoor environment and how much is leaking to the atmosphere from it. Also, the definition of the indoor environment is such that it becomes difficult to make a standard. An indoor environment is any place / location where one is not exposed to the ambient air directly. That means every place, right from schools to cars to trains and aeroplanes fall in this category. That makes a difficult job, that of specifying standards, impossible.

What then, are the sources of indoor air pollution? There are many, and a partial list can be found here: [The website of the United States Environmental Protection Agency] You will find among the many listed sources a source called Environmental Tobacco Smoke (ETS). Note the use of the word Environmental. Cigarette smoke has not been referred to directly, because cigarette smoke itself is a part of ETS. ETS is constituted by cigarette smoke as well as the smoke that the smoker exhales. Overall, ETS is more harmful than cigarette smoke by itself is.

The cigarette burns at a very high temperature when the smoker inhales and the tip of the cigarette can be at as high a temperature as 900 C. This explains why cigarette burns take so long to heal. Nicotine, the habit forming chemical present in tobacco, does not lead to the production of harmful gases / particulate matter. It is the “tar” present in the tobacco which leads to production of carbon monoxide and carcinogens and poly aromatic hydrocarbos like phenanthrene, flouranthene, etc. Carbon Monoxide, another combustion product, reduces the oxygen carrying capacity of human blood because it forms an irreversible bond with haemoglobin. Particulate matter settles in the lungs, and cigarette smoke has such small particles that they can deposit in the alveoli, which are the places where gas transfer takes place in the lungs i.e. oxygen is swapped for CO2.

The smoke that a smoker exhales has more of these smaller particles than he/she has himself/herself inhaled, because they are too small to get deposited in the smoker’s lungs. However, in the time that elapses between a smoker exhaling and a passive smoker inhaling, these condense on other particles and grow sufficiently in size to get deposited in the passive smoker’s lungs. This is what makes passive smoking such a threat to humans! There are of course many other sources of indoor air pollution and I haven’t even scratched the surface of this topic. However, I do believe that I will have generated sufficient interest in this topic by this small article for all of you to do some reading on your own. Based on the popularity of this post, I will decide whether to part with some more interesting information!
Till then, adieu!

Some links for reading up on indoor air pollution:

Govindraj Umarji


  1. Govind,
    Thanks a lot. Very nice and informative post. Would like to hear more from you on IAP

  2. Nice post and great blogging initiative. Govind what is the typical size of particles that get deposited in the lungs and the size of the particles exhaled by the smoker. Also if you could cite the reference of this study, that'll be great.

    Thanks again for the nice post

  3. Dear Snigdha,

    Will revert with the details soon. Thanks for dropping by & reading the article! :)



  4. Snigdha
    Thanks for the comments and visiting the blogspot. Do subscribe through email - that way new posts will come straight to your mailbox. Thanks

  5. Definitely thought provoking, apart from being an eye-opener for the layman!


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