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February 9, 2007
Ozone In The Low Zone
In light of the carbon challenge put forth by Sir Richard Branson, I started thinking about what are some of the greenhouse gasses we have to deal with nowadays. I decided to go back to the ozone layer problem and look at UV rays and global warming and I learned some things about ozone I hadn't known before...
They've Penetrated Our Shields: Ozone Holes
The ozone holes are located in the stratosphere, the second layer of Earth's atmosphere from the inside. It is situated between about 10 km-50 km above the Earth's surface, but only about 8 km from the surface at the poles. If you're thinking of building some sort of air filter to reach the stratosphere, then build it on one of the poles.In comparison, the main Trans-Alaska Pipeline runs 1,300 km from the Arctic Ocean at Prudhoe Bay, Alaska to the Gulf of Alaska at Valdez, Alaska. Planes routinely fly in the stratosphere.
Holes: A How To
The destruction of our nice layers of atmosphere has been attributed, at least in part, to chlorofluorocarbons (CFC's) and halons. It takes about five years for CFCs to get up to the stratosphere. Once they reach the upper ozone layer, they are no longer so protected from UVB rays from the sun. The UVB breaks down the CFC's, resulting in lots of free chlorine atoms. A single Cl atom in the stratosphere can destroy many thousands of ozone molecules.
We have too many CFCs in the stratosphere and not enough ozone. So we want to make more ozone, right? Wrong!
Good Up High - Bad Nearby
Lower in the atmosphere, like in the troposphere and on the Earth's surface, ozone is considered a bad greenhouse gas. And we have a lot of it.
According to the U.S. EPA, "10 to 20 percent of all summertime respiratory-related hospital visits in the northeastern U.S. are associated with [ground-level] ozone pollution".
Ground-level ozone is at its highest concentration in summer, so if we're going to do something drastic about ground level ozone, it makes sense to target summers as the most vital time.
We've limited CFC's, so how are we making ozone?
More sunlight (UVB radiation specifically) passes through the stratosphere, now that it has holes in it. This same UVB then interacts with the gases, both man-made and natural, which exist closer to the Earth's surface. The pollutants we emit from cars and factories react, creating harmful levels of ozone down low where we can breathe them.
We also generate ozone directly by our usage of high voltage electrical equipment like ionic air purifiers, laser printers and photocopiers. Due to its highly reactive state, ozone has been used extensively for water purification and high concentrations in the air can help decontaminate places from certain chemical or biological contaminants or odors.
However, it's nice to know that no ozone is generated when the HP LaserJet series printer is in standby mode, so you can leave it on if you need to, but printing less will limit the emissions and save trees, too.
Look Lower: Problems below the Stratosphere
Volatile organic compounds (VOCs) are emitted as gases from certain solids or liquids. There are both natural and man-made contributors to the levels of volatile organic compounds in the air we breathe. Man-made culprits include fuels, paints, solvents and glues, cleaners, pesticides, building materials, and machines like such as copiers and printers. Even permanent markers emit these harmful fumes. Basically, if you can sniff it, its likely a VOC. These noxious gases and fumes interact with the UV sunlight coming into the atmophere and generate even more ozone.
Nature Fumes
Volatile organic compounds aren't just produced by nasty manmade agents. In fact, trees are a significant producer - they emit isoprene and monoterpenes that react with nitrogen oxides (like smog) to form ozone.
There have been studies to determine which trees and shrubs produce minimal VOCs. There is even a Cal Poly project called SelecTree that helps people select tree and shrub species to plant based on their "features" including biogenic emission levels, fire resistance, and whether or not they are wildlife friendly. It shouldn't come as much of a surprise that sniffy trees like Eucalyptus top the list of VOC producers...
Posted by sorsha at February 9, 2007 7:36 PM
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Comments
So, ionic air purifiers create ozone. And ground-level ozone causes respiratory illnesses. The ionizing air purifiers are supposed to create air that is better to breathe and they're even starting to come in some cars standard.
What's up with this dilemma?
Posted by: Shane Conder | February 11, 2007 11:11 PM
Remember, ozone is used to "clean" air or remove airborne contaminates. Because ozone (O3) is highly reactive, it splits and bonds easily with other unwanted particles in the air, neutralizing them.
Basically, O3 is not tightly bonded, so one of the oxygen atoms breaks off and attaches to the bad air particle, leaving behind O2 (that stuff we need to breathe).
Oxygen is a component of many organic compounds and combines easily with most other elements. Since oxygen is the element with the second highest oxidation potential, the resulting molecule breaks down.
The problem is that many air filters don't do a very good job at cleaning the air, instead filling it with too much ozone, which has its own health issues.
For example, according to aircleaners.com,
Sharper Image shares fell nearly 9 percent after Consumer Reports claimed that Sharper Image's Ionic Breeze Quadra Silent Air Purifier and four other similar air purifiers fail to significantly clean the air -- some can also expose users to potentially harmful ozone levels.
They tested several popular ionizing cleaners and found that two of the ionizing cleaners emitted high levels of ozone in the 150-300 ppb range.
The EPA standards for outdoor ozone concentration exposure is 80 ppb over 8 hours. Exposure to ozone levels of 100 ppb can cause respiratory problems and bring on asthma-like reactions in people.
Posted by: Lauren Darcey | February 13, 2007 3:21 PM
Have been using an "Environizer ifD Air Purifier" next to bed for two nights now and feel all stuffed up in the morning. I am allergic to pollens. Is ground level ozone from this machine worsening my condition?
Posted by: Russell Strathdee | May 12, 2008 4:15 AM
Honestly, that's a question for your doctor. My suggestion is:
If your DOCTOR suggested this type of filter, give it a bit longer to work. If YOU are trying to figure how what's making you stuffed up on your own, go see an allergy specialist and follow their recommendations.
Regarding air purifiers... I would read up everything you can about the model and the type of purifier. HEPA filters are generally good. They will often have their emissions listed either on the box or on a website testing them or on their corporate website. Read the manual.
I have pretty bad allergies to dust and grasses and cats and dogs. I used to go through a couple boxes of Kleenex each week. My morning stuffed-up-ness was caused by dust mites that live in mattresses, etc. So I got allergy covers for my mattress and pillows and I wash my sheets at high temps at least once a week. Now I breathe clearly.
The best thing I ever did was go to the doctor and get tested for exactly what I was allergic to, and then follow their instructions and recommendations on lifestyle changes to minimize my contact with what makes me show allergy symptoms. Nowadays, I don't need any meds for it and I rarely need a tissue.
Posted by: Lauren Darcey | May 12, 2008 6:25 AM