Environmental Allergens
What are environmental allergens?
The environment around you is full of foreign substances. In people with environmental allergies, exposure to these substances triggers an immune response, which can result in allergy symptoms and cause discomfort.
Anything in the environment can trigger allergies, but here are the most common environmental allergens.
Pollen
Pollen is a fine powdery substance produced by plants and is transported by the wind, insects, or other animals. Depending on where you live, different types of pollen can be released.
Since pollen is an airborne allergen, exposure is most commonly through inhalation, but other routes of exposure such as skin contact and ingestion can occur.
There are three unique types of pollen that are produced by different types of plants during different times of the year: tree pollen, grass pollen, and weed pollen.
Weekly pollen counts by type, in Minneapolis, 2020:
Tree pollen
Tree pollen is usually the first type of pollen to trigger allergies each year, with its release typically being from early-April until late-May.
Some different types of tree pollen that can trigger allergies: Alder, ash, beech, birch, box elder, cedar, cottonwood, date palm, elm, mulberry, hickory, juniper, oak, pecan, Phoenix palm, red maple, silver maple, sycamore, walnut, and willow.
Grass pollen
Grass pollen is usually the second type of pollen to trigger allergies each year, with its release typically being from early-June and ending in July.
Some different types of grass pollen that can trigger allergies: Bahia, Bermuda, Fescue, Johnson, Kentucky bluegrass, Orchard, Redtop, Rye, Sweet vernal, and Timothy.
Weed pollen
Weed pollen is usually the last type of pollen to trigger allergies each year, with its release typically being from mid-June until the first hard frost. Levels of weed pollen peak in early-August through mid-October.
Some different types of weed pollen that can trigger allergies: Ragweed, Mugwort, Burning Bush, Cocklebur, English Plantain, Lamb's Quarters, Pigweed, Russian thistle, Sagebrush, and Tumbleweed.
Insects and pests
Insects and pests can be problematic for allergy sufferers both in and out of the home. There are three main insect and pest behaviors that lead to allergic reactions, invasion of indoor environments, defensive stinging, and feeding on you through biting.
Household Pests(12, 13)
Dust mites
Dust mites are insect-like pests that are too small to see without a microscope. They thrive in warm and humid environments and are commonly found in mattresses, bedding, upholstered furniture, carpets, and curtains within the home.
Dust mite allergens are proteins from dust mite feces, urine, or decaying bodies. These allergens do not typically stay in the air, as they quickly settle into dust or fabrics.
Stirring up dust makes these allergens airborne and leads to inhalation exposure. Exposure to dust mite allergens through contact or ingestion is also possible.
Cockroaches
Cockroaches are insect pests that typically shelter in dark cracks and crevices in people's homes. They are attracted to warm and humid environments and while common in rural environments, cockroaches are even more prevalent in urban areas being present in 78%-98% of urban homes.
Cockroach allergens are proteins from cockroach saliva, feces, or shedding body parts. These allergens do not typically stay in the air, as they quickly settle into dust or around the home.
Stirring up these allergens makes them airborne and leads to inhalation exposure. Exposure to cockroach allergens through contact or ingestion is also possible.
Stinging Insects14
Stinging insects such as honeybees, wasps, hornets, yellow jackets, and fire ants sting and inject venom, which typically leads to a local inflammatory reaction.
Most insect stings result in mild local reactions, but large local reactions and systemic reactions like anaphylaxis are possible and signal the presence of an allergy.
In stinging insect allergies, the allergens are proteins in the venom from a sting. Exposure to these allergens typically only occurs from getting stung.
Biting Insects
Biting insects such as mosquitos, fleas, bedbugs, flies, lice, spiders, and ticks bite and inject saliva, which typically leads to a local inflammatory reaction.
Most insect bites result in mild local reactions, but large local reactions and systemic reactions like anaphylaxis are possible and signal an allergy.
In biting insect allergies, the allergens are proteins in the saliva from a bite. Exposure to these allergens typically only occurs from getting bit.
Pets15
Pet allergies are most commonly associated with cats and dogs, but any animal kept around the home can be a source of allergies. Allergens that come from pets are through proteins in their shedding skin cells (dander), saliva, urine, and sweat. Many people think that fur is the source of allergies, but that is mainly because all different types of allergens (pollen, mold, dust mites, and pet allergens) get trapped and are present on a pet's fur.
Exposure to pet allergens commonly occurs through inhalation or contact. Dander is very small, easily stirred up, and can remain airborne for long periods of time. It also easily collects on surfaces and sticks to clothes. Saliva can also stick to surfaces and when dried, can become airborne like dander. Simple actions such as petting your dog or breathing in the household air can result in an allergic reaction.
Hypoallergenic is a term that is thrown around for pets that shed less fur than others. The theory is that less shedding results in lower quantities of airborne allergens, but in practice, someone with allergies is just as allergic to a hypoallergenic breed as the others.16
Mold17
When it comes to mold allergies, microscopic particles called mold spores are the culprit. These spores easily float through the air and stick to surfaces. Every environment, including both indoor and outdoor environments, has mold spores.
Since mold is an airborne allergen, exposure is most commonly through inhalation, but other routes of exposure such as skin contact and ingestion can occur.
Some of the most common molds that cause allergies: Alternaria, Aspergillus, Cladosporium, and Penicillium.
Drugs18
Drug allergy is when a person has an allergic response from exposure to a medication. Over-the-counter, prescription, and herbal medications all have the ability to induce a drug allergy.
Depending on the drug, exposure can occur through ingestion by taking pills, through injection via IV, through contact if applied to the skin, and inhalation if breathed in.
Common symptoms of a drug allergy include hives, rash, or fever.
Some of the most common types of medications that cause allergies are antibiotics (penicillin), pain-relievers (Aspirin, Motrin, Aleve), chemotherapy drugs, and medications for autoimmune diseases.
Latex19
Latex allergy is when a person has an allergic response from exposure to natural rubber latex, which is a product made from the rubber tree.
Exposure to latex can occur through contact with a latex-containing product or through inhalation of airborne latex particles that are released by latex products.
Common latex products: Rubber gloves, balloons, condoms, clothing, and rubber balls.
Some people with a Latex allergy experience "Latex-Food Syndrome." This has to do with protein similarity; the allergen these people are allergic to is similar to proteins in foods.
Common latex-food syndrome foods: Apple, avocado, banana, carrot, celery, chestnut, fig, kiwi, melon, nectarine, papaya, peaches, potato, and tomato.
Metals20
A metal allergy is when a person has an allergic response from exposure to metals. Exposure to metals typically only occurs through contact.
Nickel, cobalt, and chromates are the most common culprits for metal allergy, but any metal can induce an allergic response.
Common metal products that can cause a reaction: Jewelry, coins, doorknobs, tattoo inks, cell phones, glasses, clothing (buttons, zippers), and cosmetics.
Chemicals
A chemical allergy is when a person has an allergic response from exposure to a chemical. Exposure to chemicals typically occurs through contact, ingestion, or inhalation.
Contact chemicals such as:
- Formaldehyde resin from synthetic fibers (polyester) or nail care products
- Urushiol oil from poison ivy
Ingested chemicals such as:
- Food additives such as food coloring
Inhaled chemicals such as:
- Fragrances and perfumes in cosmetics
In the case of chemical allergies, a reaction to a toxic chemical like formaldehyde might be advantageous.