“Stay Indoors” is what the government and the news channel advice whenever the pollution reaches a higher level in the cities.
While walking down a busy road in an urban city, we often cover our nose and mouth to protect ourselves from dust and pollution.
Sometimes, we even wear a mask during the winters.
And we speed up our pace to reach our homes or offices. Because that’s where we know that we’ll be safe!
But, just being inside the home does not mean that you are safe. Staying indoors is good advice only if you have an efficient air purifying system in your home.
You must have heard about an Air Purifier. If you do basic research on air purifiers on the internet, you’ll come across a word, HEPA.
You can read our reviews & buying guide on Best Air Purifiers.
It is an important and popular air purification method.
So, let us delve into the concept of HEPA in air purifiers.
What Does HEPA Mean?
HEPA stands for High-Efficiency Particulate Air.
It is used to describe the filters which can trap 99.97% of the particles which are 0.3 microns or larger.
What Is the Importance of ‘0.3 Microns’ Here?
Scientists refer the micron size as MPPS (Most Penetrating Particle Size).
The particles with micron size evade the air filters more than the larger particles.
Therefore, if a filter claims that it can trap 99.9% of the large particles may be weak at capturing the ultra-fine particles.
Similarly, if a filter touts that it can trap ‘smallest’ of the particles, it isn’t telling you ‘how much small’ particles it can capture! It doesn’t tell if it can trap 0.3 microns sized particles or not, which are the most dangerous and the hardest one to filter.
Let us look at the size of various airborne particles:
|Spores||3 to 50 microns|
|Molds||3 to 12 microns|
|Bacteria||0.3 to 60 microns|
|Emissions from a Car||1 to 150 microns|
Anything which is less than 10 micrometre cannot be seen through the naked eyes.
Why Is It Important to Remove Such Small Particles From the Air?
As discussed above, scientists refer these fine particles as MPPS.
Larger particles such as pollen, mold spores, etc. are filtered out in the nose and throat.
But, some microscopic particles easily enter into the lungs and may damage our health. It may carry pathogens of a serious disease. Patients of allergies and Asthma suffers the most.
So, it is really important to filter out large as well as small particles from the air.
What Is a HEPA Filter?
HEPA is a type of high quality air filter which meets the HEPA filter standard.
A HEPA filter removes the smallest of the particles. Along with 0.3-micron sized particles, it is even more efficient at removing at PM 10, PM 2.5 and the larger ones.
How Does HEPA Filter Work in an Air Purifier?
HEPA consists of thousands of glass fibres which are arranged into a mat. They possess a diameter of 0.5 – 2.0 micrometres.
The three key factors which affect its function are:
- Diameter of the fibre.
- Thickness of the filter.
As the particles pass through the fibrous web, they are filtered out in the following ways:
The air changes its flow as it reaches the filter. Larger particles like dust, mold and pollen can’t follow the curving path of the air stream. Hence, they travel in a straight path, collide with the fibre and stick to it.
Higher the velocity of air, higher is the impaction.
The air stream carries a particle between the two fibres. If the size of the particle is larger than the gap between the fibres, it gets entrapped.
The flow of air is active enough to re-route its path around the fibres. But, with the moment of inertia, particles continue their way and stick at the fibres.
This method works on the principle of ‘Brownian Movement.’
This method filters smallest of the particles, especially less than 0.1 micrometres in size.
When these fine molecules collide with the gas molecules, they get slow down. It entraps the particles either through Impaction or Interception.
This method works the best at the lower air velocity.
Types of HEPA Filters
Depending upon the efficiency, HEPA filters have been classified with A to E stickers.
Type A is considered the least efficient while Type E, the most efficient.
Generally, Type E HEPA is used in defense-grade applications.
Vacuum cleaners make use of Type A HEPA filters which works well within our house.
Pros of Using HEPA Filters
- It captures both small and large particles, thus gives fresh and clean air.
- It keeps away 99.97% of the pollutants of minute size. So, even the dust has no chances against the HEPA.
- These are available in different sizes and cost to match the budget of your wallet.
Cons of Using HEPA Filters
- Some of the HEPA filters are washable while others are not. They can just be replaced which is a costly affair.
- Replacing the prior HEPA filters with that of branded quality shells out huge money.
- The filters need utmost care while cleaning and installing.
- A HEPA filter cannot remove gas molecules, fumes and odours, whose size is less than 0.3 micrometres.
Reasons to Choose a HEPA Filter
HEPA filters are worth buying these days as the pollution has increased to a high level. Though they are expensive, they provide value for the money you invest into buying them.
Apart from the ‘Air Pollution’ other reasons to choose a HEPA filter are :
Removing pet danders from the air saves you from allergy symptoms. An Air Purifier with both a HEPA and a Carbon filter removes allergens and odours.
Parents concerned with airborne pollutants should consider an air purifier with HEPA filter. Since a baby’s lungs are very delicate and are still developing, the presence of airborne particles may impact his health and hamper the natural growth.
By choosing a good HEPA air purifier for home, Asthma and allergy patients can enjoy a refuge from the unpleasant symptoms of the disease.
Cleaner the Home, Better the Peace of Mind
We take around 23,000 breaths every day.
Though we might not be able to control where we live, we can have some control over what we breathe.
This small change in your home can result in a big improvement which will ensure clean and safe air for you.
There are many sources by which you can buy a HEPA Filter Air Purifier. Many kinds of air purifiers are available in the market which makes use of different technologies.
Some use HEPA, Carbon, UV, Vitamin C Filters and many more.
Buy only the best quality product from the reliable sources.
Avoid buying ‘HEPA-type’ or ‘HEPA-like’ filters. These do not provide the best results as compared to a True HEPA filter.