Particle Sizes of Airborne Allergens

The particle sizes of airborne allergens are important variables in considering the effects on the human body and the likelihood of inhaling it.

The smaller the allergen, the longer it will stay airborne and the farther it can go into the respiratory passages.

The larger the allergen size, the less time it will stay airborne and the more likely that it will be trapped by the hairs and mucus in the nose.

The Micron Size of Allergens

Allergens causing allergy symptoms can range from 1-500 microns. At the larger end of the scale are dust mites and larger size pollen. Even though they are capable of triggering allergic symptoms, they settle out of the air quickly. They are less likely for to be inhaled.

The micron size of allergens causing most allergic symptoms range from 1 to 80 microns with particles under 50 microns in size being inhaled the most. Most of the pollen that triggers allergic symptoms range in size of 15 to 40 microns.

Allergens Entering into the Body

Particle sizes under 40 microns easily enter into the eyes and cause allergic symptoms. Eye allergies (Allergic Conjunctivitis) are caused by the same airborne allergens that produce hay fever symptoms including itchy, red, and watery eyes.

The micron size of the allergen particles determines how deep into the body it will penetrate.

• Allergens around 100 microns and larger are generally not inhaled very often.
• Allergens around 10 microns and larger are usually filtered out by the nose. They are caught by the hairs and/or mucus in the nose.
• Allergens between 4 to 10 microns can get past the nose and reach the bronchi tubes. This size and smaller is especially dangerous for people who have asthma.
• Allergens smaller than 4 microns can reach beyond the bronchi and enter into the lungs themselves.

Settle Time

The time it takes for particles to settle out of the air is another important variable. The longer an allergen stays airborne, the more of a chance it can be inhaled and produce allergic rhinitis symptoms.

The density of the particle and the aerodynamic properties of the allergen, along with the size, will play a role in the time it takes for it to settle out of the air. If the shape of the allergen is thin and flat, it will stay aloft longer than round or oval shapes from allergens of the same size. For example, cockroach wing parts could possible stay airborne longer than its fecal waste matter.

The way of nature to spread different kinds of pollen is by using the wind. This type of pollen has many aerodynamic characteristics that will allow it to catch wind currents and stay aloft.

Particle sizes larger than 40 microns tend to settle out of the air quickly, resulting in less being breathed in. Particle sizes above 50 microns will begin collecting together making the visible household dust that we see in our homes.

At the smaller end of the scale, allergens under 10 microns do not settle very quickly. It is estimated that the particle size of 5 microns could take up to 4-6 hours to drop 10 feet (from the ceiling to the floor). This happens under the conditions of no air movement. It takes longer for settling if someone is walking around in the room and disturbing the air.

Allergens Becoming Airborne

The small allergens can be propelled into the air easier than larger and heavier size particles. The way in which these particles are propelled into the air can make a difference also. Walking on the carpet may send allergens into the air. However, walking on the carpet may not send the particles very high into the air. Considering the average height of people, our noses may not be affected by this. On the other hand, vacuuming the carpet without a HEPA filter can propel the allergen high enough to cause problems and longer settling times.

Particle Sizes of Allergens

Below is a general range of particle sizes in microns. All these have the potential to be smaller as nature performs the natural process of decay.

Summary

Allergens can be very small in size. This small size and light weight keeps the particles airborne for a while before settling.

Human hair comes in a side variety of thickness and diameter. As a general rule, the micron size of human hair is considered to be between 80 to 120 microns. One single strand of hair is easily seen because of the length. But would it be so easy to see if the length was the same size as the width? The point is; the human eye (with good vision) can see down to about 70 microns. These allergens are much smaller than that.

Pet allergens and mold spores are the smaller particle sizes. It is easy to see why their size can present problems when you compare them to:

Go to the nasal allergy HOME PAGE from particle sizes.

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