The Biology of House Dust Mites and Dust Mite Allergies

House Dust Mites (HDM) are a major source of allergen and found in temperate and humid areas. There is widely published data that shows how House Dust Mites avoidance can reduce exposure to allergens. This article looks at the properties of house dust mite and recommendations for reducing HDM in the home.

Biology of the house dust mite

House Dust Mites are arachnids not insects and related to ticks and spiders such as daddy long legs. Thirteen species of HDM have been found in dust however the two which are the most common and are the main source of the HDM allergen are Dermatophagoides farinae and Dermatophagoides pteronyssinus from the family Pyroglyphidae. The life cycle of the HDM Dermatophagoides pteronyssinus consists of 5 stages. An adult mated  먹튀검증사이트 female will lay 40 – 80 eggs in her lifetime, when the egg hatches a six legged larva emerges. There are two nymphal stages (which feed and moult before an eight legged adult is developed. The adult HDM has a mouth-like appendage and no eyes or antennae. The duration of the cycle is usually one month and dependent on the climate, ideally 25°C and 75% RH. An adult HDM can live for one to three months under favourable conditions.

Their translucent body is 300µm – 400µm in length and only visible under a microscope with the faecal pellets ranging from 20µm – 50µm, it is estimated that the HDM can produce 20 pellets per day. HDM are ~75% water by weight and therefore need to absorb water from the water vapour in the air making relative humidity (RH) a critical factor for survival.

Dust Mite Habitat

HDM primarily feed on organic detritus such as flakes of shed skin, other nutrients are provided by animal dander, pollen, bacteria and mould. HDM survive and reproduce the best in soft furnishings such as carpets with long pile, bedding and plush toys, which contains a large supply of their food source, this stable environmental dwelling is best provided by homes. Indoor humidity is very important and when it is less than 50% they are unable to maintain their water balance and are more susceptible to desiccation.

The HDM selects food that has been pre decomposed by fungi which reduces the fat content of the skin cells. The fungi in turn are using the house dust mite faeces and skin cells as a source of nitrogen (Woodcock et al. 2006) which forms a minute ecosystem in their environment.

Dust Mite Allergies

Allergy is a response of the human immune system to a foreign protein substance (allergen). A HDM allergy is the result of a hypersensitive immune system response to the mite faces. Faecal pellets are easily airborne and when they become suspended in the air they can be inhaled, the allergic reaction will cause sneezing, wheezing, headaches, coughing, eye irritation, fatigue or dizziness and are confirmed as a major trigger for acute asthma attacks in sensitive individuals. Roughly 1-2 % of the world population (65-130 million people are allergic to house dust mites (Collof, 1999)

Dermatophagoides farinae (commonly found in drier regions) and Dermatophagoides pteronyssinus (commonly found in temperate to tropical regions), produce at least ninteen different allergens each. These allergens are further classified depending on their biochemical characteristic by group numbers:

Group 1 allergens (Der p 1, Der f 1), glycoproteins originating from the digestive tract of the mites.

Group 2 allergens (Der p 2, Der f 2), non-glycosylated proteins with a high IgE binding capacity and associated with the mite bodies.

Group 3 allergens are associated with digestive enzymes, Group 4 allergens are sugar associated and so on.

Around 80% of mite allergic patients are sensitive to Group 1 and Group 2 allergens from HDM (Thomas, WR et al. 2004). Examples of other allergens include pollen, pet dander and mould. Allergy is the 5th leading chronic disease in the U.S. among all ages, and the 3rd most common chronic disease among children under 18 years old as reported in “Chronic Conditions: A Challenge for the 21st Centrury,” National Academy on an Aging Society, 2000

How to control allergen levels in the home

There is no cure for allergies to dust mites. The only way to avoid allergy symptoms when it comes to dust mites is to prevent exposure. The use of a multifactor approach to allergen control has been recommended by, the Report on the Third International Workshop on Indoor Allergens and Asthma (1997) as well as the National Heart, Lung and Blood Institute’s (NHLBI) National Asthma Education and Prevention Program (2007).

Maintaining RH below 50% by using dehumidifiers in homes is effective in reducing RH and therefore reducing mite populations. Regular vacuuming and steam cleaning carpets can kill mites and remove surface allergens. Encasing mattresses and pillows with products that have verified allergen barrier properties are effective in reducing exposure to HDM and their allergens.

Many products claim to reduce allergens without independent evaluation of their effectiveness making it difficult for the consumer to make the right choice; however Allergy Standards Limited (ASL) an international standards and certification body helps consumers and retailers identify toys, bedding, vacuum cleaners, dehumidifiers etc. for people concerned about allergies, asthma and indoor air quality. ASL’s independent certification standards have been written in consultation with industry, retailer and health care professionals and are the only standards that are accepted by the Asthma and Allergy Foundation of America. Reputable retailers should ensure that all allergen claims have been conducted in a meaningful way to avoid falling foul of labelling guidelines. Concerned consumers should also seek that all labelling where allergies are concerned have been validated by a third party independent testing authority.

ASL believes that a home allergen reduction plan which incorporates a number of changes is critical for reducing exposure to allergens.

The independent testing and research for the Asthma and Allergy Foundation of America certification program is conducted by the life sciences company airmid healthgroup ltd (AHG). The airmid healthgroup ltd research spans all disciplines relevant to indoor particulate contaminants, ranging from virology, microbiology, mycology, allergen, dust mite and bed bug research. The airmid healthgroup ltd laboratory offers a complete range of advanced Allergen Testing Services specialising in Allergen Barrier Services, Dust Mite related Testing, Claim verification services and Allergen detection.

Security Doors in the Workplace – Wood or Steel Security Doors?

For any business considering an investment in high security doors and are unsure whether to opt for wood or steel doors the following real life story will help make that decision;

A high-rise apartment building wished to offer residents the highest possible security. Double steel security doors were installed in every unit. One day whilst out & about, an elderly tenant had an accident and was taken to the hospital. Neighbours became worried when they noticed his untouched newspaper outside his apartment the following day and called the police to break in to see if the elderly gentleman was in trouble. The police and fire departments thought the door was a painted wooden one and attempted to break their way in. Upon realising it was a steel security door, they sent for additional assistance. After almost an hour using two determined workers with special tools the rescue team pried the steel framework apart enough to disengage the locks on this 30 year old steel door. The high security steel doors had done their job!

Statistics reflect that more than 70% of burglars focus on a building’s door to gain entry. No matter how high quality the locks may be, if a wooden door can be broken the locks are useless, unlike steel doors.

If the workplace consists of several offices/rooms in a commercial building open to the public a business is at even greater risk and security alarms often do not bring authorities until 10 or 15 minutes have passed. This is plenty of time for a wooden door or doorframe to be broken, the workplace entered, and valuables taken. There is a reason that most safes and safe deposit boxes aren’t made of wood!

With steel security doors tests on their strength are an industry requirement. These tests guarantee buyers that steel doors cannot be broken into in such a manner.

Every aspect of steel security doors’ design, manufacture and installation guarantee that a buyer is obtaining the optimum in security. This offers a peace of mind that is hard to find with other types of high security doors, and should be a priority to most business owners. Plus, although “fire doors” can be purchased, businesses still receive excellent protection against the spread of fire with steel security doors. (Providers should have their doors’ fire ratings and fire resistance standards available for discussion.) Steel doors also provide increased energy efficiency, since they insulate the cold air from outside up to 4 times better than wooden doors.

Steel doors are made to a building’s specifications, with many factors measured for an exact fit. Openings for the locks are expertly engineered with no room for error. The metal framework fits perfectly to eliminate any space in which Security doors & Window to slide the slimmest tool or crowbars. Installers take special measures to ensure the heavy doors are hung with perfect balance and all hardware is flush with surrounding surfaces. The entire process, including manufacture and delivery, can take several weeks, and the installation can require 5 hours, but the steel security door can last forever. It can’t rot, warp or otherwise change shape, thus eliminating a potentially dangerous situation!

There are many choices open to a business which is considering steel security doors, and after discussing the many options with a professional supplier, the buyer will know that they are getting a door that meets their unique needs. However, there are some aspects of high security doors that are standard, such as protections from rust and corrosion, various designs and finishes (most which require no maintenance), and the opportunity to choose locking mechanisms and the direction of swing. Some doors offer anti-lever cover plates, anti-crushing surfaces, anti-jimmy strips and reinforced steel edges to further enhance protection. With more than 65% of homeowners choosing entry doors made of steel, it makes sense for a business to consider them as well! Since every kind of steel security door can be accommodated by existing structures, even a business located in an old garage, carriage house, or condominium can take advantage of the protection it offers. Materials used in construction include galvanized or zintec steel. A few points to remember are that, when comparing types of steel, the stronger the steel, the lower the gauge number it carries. (Plus, the stronger it is, the more the steel will resist dents.) This number should be referred to as “true gauge” and not “nominal”, since the latter means it’s not quite at the rating it’s carrying. In addition, hot-dip galvanizing appears to offer more protection against rust than electro-galvanizing, which may leave some areas uncovered.

A steel door specialist can discuss what may be best for a buyer’s needs, and can explain the guarantee of parts, manufacture and anti-perforation abilities. He or she can also explain the pricing options; steel security doors range greatly in price, depending on customer choice. However, it is possible to purchase a high quality, high security door for less than expected. Although it may be a little more expensive than a standard wooden door, the benefits are definitely worth it!