UV Air Purifiers

UV (ultraviolet) light is another popular technology used in air purifiers. UV light is very effective in destroying airborne pathogens such germs, viruses, and bacterias. In fact, the CDC (Center for Disease Control) recommends UV light radiation as a method to prevent illness and disease.

An UV Air Purifier works by destroying the DNA of microbes such as yeast, mold, bacteria, viruses, and fungus. This causes these microbes unable to reproduce.

Air is drawn into the air purifier and passes through the UV light attached in the unit. The radiation from the UV light will then destroy the microbes and viruses.

Many modern hybrid air purifiers now includes UV in their technology because UV light is safe, effective and economical.

Gas Phased (activated carbon) Air Purifiers

Let's take a look at Gas Phase Air purifiers. Mechanical (eg. HEPA) and electronic air purifiers cannot remove gases and odors that are typically 0.3 microns or smaller. What is needed is a filtration system usually uses activated carbon to absorb these gases - usually called "gas phased" or "activated carbon" air purifiers

Activated carbon is basically charcoal that has been treated with oxygen and it has millions of tiny pores between the carbon atoms. The pores in these gase phased air purifiers then absorb the gas molecules, hence the name 'gas phase filters'.

When choosing a gas phased air purifier, you need to check the following:

Find out the quantity of activated carbon in the filter
The more activated carbon the air purifier has, the better it is in absorbing gases.

The thickness of the activated carbon filter.
A thick filter has a higher adsorption efficency because the gaseous pollutant has to go through a long maze of activated carbon.

Type of activated carbon - Impregnated carbon fiber pad or granular activated carbon? Air purifiers with granular activated carbon is more effective. I've explained why in this artile, activated carbon air purifiers

HEPA Air Purifiers

One of the favorite air purifiers are the HEPA based units. HEPA stands for "High Efficiency Particulate Arresting" and it was originally developed during the World War II by the US Atomic Commissions to protect its researchers from toxic particles. Since then, the HEPA technology has been widely used in many air purifiers

True HEPA filters are made from from high grade paper that acts as filters to remove 99.97% of all pollutants that are greater than 0.3 microns in size. There are many filters out there that has a "HEPA-Type" label on the air purifier units. . These are not true HEPA filters, and their efficiency ranges from 25% - 95% depending on the material used and the design.

True HEPA filters are recognized by OSHA/EPA as a proven method of cleaning the air. It's often regarded as the best form of air filtration. "Clean rooms" in hospitals, laboratories and high-tech research rooms often emply HEPA filters to create a contamination free environments.

If you want to read more about HEPA filters, follow this link: HEPA air purifiers

Ozone Air Purifiers

Ozone Air Purifiers is perhaps the most 'controversial' type of air purifiers. The safety of using an ozone purifier has been (and still is) being debated by various groups of people. How safe is an ozone air purifier?

Before we get into that, ozone is actually "activated oxygen", i.e. it has 3 atoms of oxygen - instead of the usual 2. This causes it to be highly reactive and it's a very strong oxidizing agent. When it comes into contact with air-borned pollutants, it loses one of its atoms and thus destroy the pollutant by "oxidizing" it. Ozone air purifiers have been known to remove mildew, bateria, odors and tobacco smoke.
I've personally tested a unit which was quite effective in eliminate petrol fumes.

Why is ozone considered harmful to humans? The same oxidizing properties that allow high concentrations of ozone to react with air borned pollutants also allows it to react with the chemicals/cells in our bodies. When inhaled, high concentration of ozone can damage the lungs. It has been known to cause chest pain, coughing, shortness of breath, and, throat irritation.

So, if ozone is harmful, why do manufacturers still use ozone? And why do some people still swears by them? For one, they do work in removing odors and some chemical pollutants, and the health effect (if any) may not be seen or felt immediately. Also, some manufacturers recommend that the air purifiers be switched on in an empty room to 'sanitize' or clean the room.

Note: the FDA stats that all sanitizers and air purifiers that emits ozone, should not exceed the 0.05 ppm concentration. Most if not all reputable air purifier manufacturers ensure that their air purifier unit will not exceed that level when operated according to their instructions.

So, what's my recommendation? Well, do your own research - search for ozone, safety, health, etc. If you're in doubt or you're not comfortable, then don't. If you're interested, you can learn more about the 5 different types of air purifiers

Which Air Purifier is the best?

Contrary to what some marketing literature may say, there is no such thing as the "best air purifier". There is no (not yet at least) single air purifier that can clean all the pollutants from the air.

The first thing you need to ask yourself is this - why do you need an air purifer for? Do you suffer from asthma as a result of some allergens such as pollen, dusts, etc? Do you live in an industrial area where there are toxic chemical fumes in the air?

In the first case, a good HEPA based filter OR a good Ionic Air Purifier will meet your needs.

In the 2nd case, you will need a Gas phased filter air purifier to absorb the chemical fumes.

Once you've determined the reason you need your air purifier, you can then make an informed choice. Here are the top 10 Tips that I've compiled on How to choose an Air-Purifier

5 Types of Air Purifiers

Although there are hundreds of different models and brand name air purifiers, there are essentially only 5 different types of air purifiers

These types are based on the technology used in the air purifier, i.e.

• HEPA air purifer
  
• UV Air Purifiers
  
• Ozone Air Purifier
  
• Negative Ion (ionizer) Purifier
  
• Gas Phased (activated carbon) Air Purifier
  

Of course, most if not all modern air purifiers sold in the stores are "hybrid air purifiers" - i.e. they use a combination of 2 or more of the technologies mentioned above.

For example, the air purifier that I personally use has a combination is an ionic air purifier with a germicidal UV lamp (a special Ultra violet lamp that renders bacteria and viruses harmless by destroying their DNA). This is an example of a hybrid air purifier

Indoor Air Quality

In my research for a good quality air purifier, I came across this shocking statement about the quality of indoor air in our homes:

"In April 1995, the US EPA (Environment Protection Agency) released an article stating that the air within homes and other buildings can be more seriously polluted (up to 2-5 times more polluted) than the outdoor air in even the largest and most industrialized cities."

In my case, I never noticed it until my neighbor started his renovation work. All the extra saw dust and air-borned particles finally caused my body to object by sneezing and coughing.

I found this fact quite interesting - an average person inhales 62 pounds (or 3400 galons) of air per day - I can just imagine the work our respiratory track and lungs
have to do each day to filter out all the pollutants from the air we breathe each day.

It's sad, but I guess nowadays, a good quality air purifier is becoming a necessity instead of luxury. The price to pay for "advancement" and "industrialization" I supppose!

Why a blog on pure air and air purifiers

About 3 months ago, my neighbor started a major renovation to their house. They were extending their kitchen. Everyday, the workmen hammered, sawed and worked from 9am to around 4pm.

At the end of the day, there were a fine layer of saw dust on my furniture. That's when I started to sneeze and cough. Each morning, I woke up with thick flem in my throat. It grew worst until I had to see my doctor.

He advised me to wear a mask. I did ... it helped a little but it was very uncomfortable. A friend at work suggested why not get an air purifier.

I started looking and searching the net. To my surprise, there were so many models
and brands of air purifiers to choose from. That prompted me to enquire further.

I've compiled all the data on indoor air quality and air purifiers on this website on all about air purifiers to share my findings.