Dublin Air Pollution Illustrated (photo)

by Mags Thu Apr 10, 2003 17:33

I noticed that last night, in the dark and from a fair distance. I was wondering if it was part of the design, but it clearly wasn't. So that is what gets in our lungs :(

by Daithi Thu Apr 10, 2003 17:38

Don't worry JD. In a few weeks time the spire will be the same colour from top to bottom once more...

by Raymond McInerney Thu Apr 10, 2003 17:42

Maybe the dull colour is an oxide layer formed on the surface of the spire to protect it from corrosion.

by kokomero Thu Apr 10, 2003 18:28

Sorry to disagree with you Ray but the spike is stainless steel and Iron Oxides are reddish in colour.

Rust is the common name for a very common compound, iron oxide. Iron oxide, the chemical Fe2O3, is common because iron combines very readily with oxygen -- so readily, in fact, that pure iron is only rarely found in nature. Iron (or steel) rusting is an example of corrosion -- an electrochemical process involving an anode (a piece of metal that readily gives up electrons), an electrolyte (a liquid that helps electrons move) and a cathode (a piece of metal that readily accepts electrons). When a piece of metal corrodes, the electrolyte helps provide oxygen to the anode. As oxygen combines with the metal, electrons are liberated. When they flow through the electrolyte to the cathode, the metal of the anode disappears, swept away by the electrical flow or converted into metal cations in a form such as rust.

For iron to become iron oxide, three things are required: iron, water and oxygen. Here's what happens when the three get together:

When a drop of water hits an iron object, two things begin to happen almost immediately. First, the water, a good electrolyte, combines with carbon dioxide in the air to form a weak carbonic acid, an even better electrolyte. As the acid is formed and the iron dissolved, some of the water will begin to break down into its component pieces -- hydrogen and oxygen. The free oxygen and dissolved iron bond into iron oxide, in the process freeing electrons. The electrons liberated from the anode portion of the iron flow to the cathode, which may be a piece of a metal less electrically reactive than iron, or another point on the piece of iron itself.

The chemical compounds found in liquids like acid rain, seawater and the salt-loaded spray from snow-belt roads make them better electrolytes than pure water, allowing their presence to speed the process of rusting on iron and other forms of corrosion on other metals.

Here are some interesting links:

Materials Science and Technology Teacher's Workshop
What is Corrosion?
Corrosionsource.com
How does iron rust?

http://science.howstuffworks.com/iron4.htm

by Joe Murphy Thu Apr 10, 2003 18:36 doire98 at yahoo dot com

The levels of pollution in Dublin city centre seem to be getting worse. Quite a lot of cars still use O'Connell Street regardless of the attempts by the Corporation to reduce non public transport use.
You can taste the pollution hitting you in mouth as you wait for a bus, my sympathy to anyone with a particular breathing difficulty trying to walk through the city centre.

by Ray McInerney Thu Apr 10, 2003 18:36

But doesn't stainless steel when exposed to air become some what dull, something similar to aluminium.

Not disputing that pollution is having an affect.

by Phuq Hedd Thu Apr 10, 2003 19:06

There are at least 5 different main types of stainless steel. They have different rates of corrosion (loss of valence electrons) in different conditions.

It is entirely plausible that the "stainless steel" is corroding.

The discolouration is not evidence on its own for "pollution" (which is an undefined term) which has been better measured by several studies undertaken over years.

Raymond's point is valid and claiming that the tarnishing of the spike is evidence (for what? CO2?, particulates?) looks hysterical.

by Phuq Hedd Thu Apr 10, 2003 19:10

what actually makes the most common stainless steels, "stainless" is a layer of oxidized iron/chromium on the outside that forms a dense film which prevents oxygen etc from penetrating and "rusting" the iron.

by won't say Thu Apr 10, 2003 19:20

It might affect your health or even shorten your life a bit but its worth it to be able to travel around the city at around of 6 miles an hour IN YOUR VERY OWN CAR.

That's progress.

by Gaillimhed Fri Apr 11, 2003 12:24

Argue as you will over whether the spike is discoloured from pollution or weathering but the fact is that when you arrive in dublin and step out into the city air the first thing you notice is that taste of engine, that chokey smell that clings to the bottom of your lungs and makes your snot go black, mixed up with the charnel house stench from McDonalds et al of flash-cooked industrial meat products. Not to mention the smell from the overflowing bins in their back alleys chock full of decomposing happy-meals not purchased within 10 minutes of cooking, and their attendant vermin.
Thats enough to turn anything a funny colour.

by me - in a personal capacity Fri Apr 11, 2003 15:13

Woooo hooooo