sharing our knowledge.
Photographic gallery.  Thousands of particles under the microscope.

Home Particles in General

The most common dust particles in homes are clothing fiber, skin flakes, and paper fiber. These all appear as "white dust". The relative contribution of each of these three will vary depending on the size of the home, the number of people in the space, and the habits of the individuals in that space. Skin flakes tend to dominate in apartments or homes of smaller volume occupied by two or more individuals. Clothing fiber may dominate in homes where frequent laundering or drier vent issues may be present. Paper fiber may dominate where tissues are frequently used, newspapers are read, etc. Pet debris, road debris, plant material, insect debris, fungal debris, spider and mite debris, cleaning residues, combustion products, construction debris, etc., begin to individualize each home environment. The contribution of dusts from pets includes dander, hair, fecal material, flea debris, pet powders, food debris, cat box debris, etc. Road debris includes natural minerals, tire wear, wear metals, soot, cenospheres, tailpipe emissions, nitrates, etc. The relative contribution of these materials is dependent on the types of roads close to the home, the amount of truck verse car traffic, the total amount of traffic, the outdoor/indoor exchange rate (high with open windows), the presence of an attached garage and how it is used, etc. Plant material, including pollen, can be a good indicator of the outdoor/indoor air exchange rate. Pollens are good indicators of the time of year (time of dust accumulation) as well as infiltration rates and particle persistence in the environment. Insect debris includes outdoor insects that are visitors as well as those that make their home in your home. The ones that live in the home tend to be the most bothersome from a health perspective, though some are potentially beneficial. Fungal debris often enters the home with pollen and other outdoor plant material. It is a problem if growing indoors and indicates a moisture control issue. Moisture management is the ultimate solution. The mite population in a home is generally of greater health concern than the spider population. There are in excess of one hundred types of mites that may live in the home. Most of these generate powerful allergens. The Dermatophagoides are the most common but certainly not the only mites of concern. Testing only for the Dermatophagoides allergens is not an effective test for the presence of mites. Cleaning residues includes a wide variety of particle types. They range from the agglomerates that are created as well a residual detergents, fresheners, etc., that add to the chemical background in the home. Combustion products include soot from candles, smoking, fireplaces, leaking furnaces, wood stoves, vehicle emissions, cooking emissions, house fires, backyard burning, etc. These particles can be indicators of serious carbon monoxide exposure issues in the home. Construction debris may be from the original construction or from remodeling. In either case, if not done properly it can be a source of irritants in the home that may persist for years. Human Skin Phase These are Human Skin Flakes with Phase Contrast Illumination. Notice the tendency to be roughly polygonal. When viewed with polarized light the cells can show stress birefringence.

Human Skin X-Pols Human Skin Flakes and Clothing Fiber Human Skin Flakes

Click here for more photos in this category Clothing fiber, as used here, refers to any textile fiber regardless of use. Environments both inside and out contain large numbers of these fibers. Most of these fibers are derived from clothing but carpets and other cloth surfaces also contribute to the environment.

Mixed Clothing Fiber This is an image from an environmental tapelift collected in a home. There are a number of different types of fibers in this image. The fiber running diagonally in the upper left corner is wool. The fiber bent in a "V" on its side in the lower center of the image is a linen fiber. The reddish fiber snaking through the image is a rayon fiber dyed red. The blue fiber running from the upper center to the center right is a mercerized cotton cotton fiber dyed blue. < Cotton Mercerized Cotton, Cat Hair, and Feather Barbule

Click here for more photos in this category

Paper Fiber

Paper and Insect Fiber Bag Cell

Click here for more photos in this category Bird Debris

Feather Barbule

Click here for more photos in this category

Cat Debris

Cat Skin Cat Skin Cat42 400Xa Cat-Tabby 1e Near End

Dog Debris

Dog Dander Dog Dander Dog43 400X1 Scale Dog Hair Near Root End

Guinea Pig Debris

Guinea Pig +200X Mid Shaft2 Guinea Pig +200X Fleece Guinea Pig +200X Near Tip

Click here for more Guinea Pig Debris photos

Mouse and Rat Debris

Mouse Hair Mouse Hair Mouse Hair Rat Hair

Click here for more Rat and Mouse Debris photos

Rabbit Debris

Click here for more Rabbit Debris photos

Construction Residue Construction Residue Construction Residue Construction Residue

Click here for more Construction Debris photos Paint Sphere Under the Microscope Paint Sphere Under the Microscope Paint Sphere Under the Microscope

Click here for more Paint Spheres Cosmetics

Click here for more photos in this category Charred Wood Charred Wood Mesquite Char Charred Wood

Click here for more photos in this category

Natural gas fired fireplaces introduce relatively small amount of soot and other particles into the home but they do contribute some. Heat modified glass fibers, the mock ember bed, may also be introduce into the living space.

Fireplace Fiber

The dark shading that forms behind picture frames on walls, at the baseboard, on walls at the ceiling, above incandescent lights near the ceiling, and other locations are due to the diffusional deposition of very small particles, typically dominated by combustion particles such as soot.

Black on Carpet Edge Ghosting Behind Picture Frame Ghosting Behind Picture Frame Ghosting on Ceiling and Walls Ghosting

Humans generate as much as 5 million skin flakes per minute in the home.

Human Skin Phase Human Skin X-Pols

Humus is a broad category that includes degraded biological materials that come in on shoes, on pets, or from animals in the environment.

Humus 400X AM#3 Feces

There are over 120 different types of mites that live in homes. Most of them can cause health effects in sensitive people. Typical allergen testing is sensitive to only two types of mite and these two are often not the most common in a home. Mite allergens are in the frass (feces) as well as the body parts of the mite.

400X AM#3 Feces Dust Mite Tyrophagus Mite Mite in Household Dust Dust Mite Tarsonemus Male Tarsonemus Male Tarsonemus Female

Click here for more photos in this category

Starch is a very common particle in all environments but can be very high in homes. Starch is used in cosmetics, body powders, as a powder on elastomers and plastics to prevent sticking, in some carpet fresheners, food, etc. Bathrooms, bedrooms, and the kitchen tend to be the rooms with the most starch. The last set of three photographs show the same field of view with different analytical lighting.

Starch Rice + Potato Starch Starch Starch

Click here for more photos in this category

Cigarette ash has a very high crystalline ash content due to the potassium nitrate and other additives to the tobacco. Cigar ash and other plant ashes have much less optically active ash. There is generally some charred plant residue that can be used to identify leaf or other plant parts.

Cigarette Smoke Cigarette Smoke Cigarette Smoke

These particle are an indication of the intrusion of exterior air or track-in debris into the interior space.

Click here for more photos of Tire Wear
Click here for more photos of Natural Minerals
Click here for more photos of Cenospheres
Click here for more photos of Charred Wood
Click here for more photos of Insect Parts
Click here for more photos of Plant Parts
Click here for more photos of Pollens
Click here for more photos of Fern Parts and Spores
Click here for more photos of Fungal Debris and Spores
Click here for more photos of Flyash

These particles are the result of exposure to smoke from fires inside or out side the home.

Click here for more photos of Fire Related Particles