Monday, May 2, 2011

Why some gases are Deadly Dangerous-O3 and Odours

The last post asked what we'd do if we had to make a choice between the environment and some of our life giving activities. It is a tough choice to make. At a certain point in time will we have to make that choice? Not if we modify our activities to benefit both - us and the environment.

To be able to do that we first need to understand what exactly human activities have been responsible for.
To date what we've done is, taken a resource from the earth, used it to make whatever's useful and ended the process there. We haven’t had to think about what by-product we’ve created.

All too often this has been a pollutant that poisons our air, waters and soil and damages our health.

a. This article tells us why certain gases like ground level ozone are deadly dangerous for our health. It helps us understand why these gases shouldn’t be the end product of our activities.
b. Ground level ozone shouldn't be confused with stratospheric ozone which is a protective layer of ozone.
c. This article also explains how dangerous odours from garbage, sewage, and industrial processes are for human health.


Ozone or O3 is naturally present in the stratosphere – high above the earth. This ozone layer acts like a shield and prevents dangerous parts of UV light from the sun to reach the Earth. This ozone layer is highly desirable. It is the beneficial layer of ozone. Unfortunately, due to human activities, the ozone in our stratosphere is getting depleted.

In New Zealand, they inform us there is a hole in the ozone layer and we are advised daily that “burn time” is so many minutes (this number varies). This means that we should remain in the sun only for that many minutes, say seventeen minutes, and then move into the shade. We are constantly advised to slap on “sun block”, wear hats, thin long sleeves in summer and take precautions so that we aren’t exposed to the dangerous parts of UV light from the sun.

There is a high risk of skin cancer in places whose ozone layer has been depleted by human activity. The harmful UV rays could also give us cataract, impaired immune systems, destroy plants and plankton which is food for marine life and the most effective carbon absorber on planet Earth.

Which Human Activities cause ozone depletion in the Stratosphere?

Ozone-depleting agents are used in coolants, foaming agents, fire extinguishers, solvents, and aerosols. It sometimes takes these ozone-depleting chemicals years to reach the stratosphere. Substances released into the air today will contribute to ozone destruction well into the future. The main culprits are chlorine and bromine compounds.
One chlorine or bromine molecule can destroy 100,000 ozone molecules, so ozone is currently being destroyed much more quickly than nature can replace it.

Ground Level (or Dangerous) Ozone and Smog

Smog Over Delhi from Google Free Images Courtesy:
The ozone that is dangerous to human health is ground level ozone. It is exactly the same chemical formula as stratospheric (or protective) ozone – O3. Yet, it is a major health hazard and a major constituent of photochemical smog.
Previously smog was a combination of just smoke and fog. Today smog is a chemical mixture of various gases and particulate matter (PM) that forms a brownish-yellow haze primarily over urban areas.
Nitrogen oxides and hydrocarbons (except methane) react in the presence of heat and sunlight to form ozone. It is a white haze that can be seen over many modern cities, especially the ones with sunny, warm, dry climates and a large number of motor vehicles. Because it travels with the wind, it can affect sparsely populated areas as well. It is close to the Earth in the troposphere and is called tropospheric ozone. This ozone is one component of smog.

It reacts with other components like sulphur dioxide, VOCs etc in various ways to form the brownish yellow haze, the modern day smog, that we see over so many cities with a poorly controlled environment. As the smog levels build, polluted air can be trapped and re-circulated for days so that car exhaust fumes are found in our atmosphere even when we aren’t driving.

Ground level ozone becomes a threat to the functioning of all living things after it reaches 82 ppb (parts per billion).
What are the effects of ground level ozone on our environment and health? 

Human exposure to ozone can produce shortness of breath and, over time, permanent lung damage. Research shows that ozone may be harmful at levels even lower than the current federal air standard Excessive ground level ozone can cause breathing problems, irritation, congestion, coughing, chest pain and swelling in the lungs. It triggers asthma. Even healthy adults and children get affected.
It affects the immune system. Many of the chemicals that cause ground-level ozone also contribute to other health effects, including cancer, and tissue and organ damage.
High ozone concentrations also cause damage to the leaves of plants, resulting in the loss of agricultural crop yields and forest ecosystems.

Odours such as from garbage, sewage, and industrial processes

Everyone knows the dangers to health and the environment of spitting, rubbish throwing, urinating and defecating on our streets. We all know the dangers of garbage piled high on our streets. What we don’t know is that apart from hygiene issues, it badly affects our olfactory (smell) and other systems.

As a result we have varied reactions like eye irritations and sore throats, coughs, drowsiness, asthma and even depression.

Odours disturb concentration and diminish productivity as our disgust with our environment remains uppermost in our minds.

At the same time, we tend to ignore and not complain about our symptoms of discomfort but productivity in such an environment goes down considerably. Our ability to perform tasks may decrease as our dislike for particular odours increases. Work force populations vary in levels of discomfort from odours because of exposure history and habituation. But whether we may, or may not realize the possible risks of consistent bad odours, they affect human health and well being.

All images from here


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Some other gases that are harmful to humans. Click on each:

Carbon Monoxide  

Carbon Dioxide  

Sulphur Dioxide  

Nitrogen Dioxide  

Acid Rain

Particulate Matter  

Ground Level Ozone and Odours



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