Millions of tiny critters fight over food and a comfortable place to settle and multiply. Fortunately you can’t see them, because most are too small to be seen. Biological contaminants are either living organisms, such as bacteria, viruses, fungi and dust mites; or are organic dead substances, such as animal dander and dried insect droppings.
Cleaning will reduce the number of settled pollutants on e.g. your bookshelves or the carpet. The emphasis is on ‘settled,’ because the slightest air movements may catapult the microscopic substances into the air where they may remain suspended for hours, sometimes days – depending on their size and weight.
Like you and I, these little polluters like to live in comfort. While we, however, may not like warm and humid conditions, most of them do. But some don’t care about the temperature and also thrive in cool and damp places. The nastier ones, like viruses and bacteria, prefer a living host as their home. Another condition for the living organisms to survive is the availability of food – nutrients. In that instance they aren’t very fussy. A bit of damp wallpaper or fabric will do fine.
Despite someone’s claim of a spotless home, there are many potential places where biological pollutants can hide. Some, such as plant pollen, are drawn in from the garden and drift in the indoor air until a person inhales the allergen. Or they hide somewhere in the home until a disturbance raises them back into the air. Others are invited by air inlets that draw their ‘fresh’ air from near a site of potential contamination, such as is the case when an air inlet is located underneath a gutter with standing water, or a bird thought the eaves just above the inlet are an excellent place to raise some young.
Air conditioning and heating systems, especially if they are ducted, are a major source of contamination, because the air conditioner generates water through condensation and the ducts will invariably become dusty. Have you thought of cleaning the drip pan behind your refrigerator? Just like an air conditioner, the cooling coils of the refrigerator condense water vapour and the excess drips into the pan.
In the kitchen, the bathroom and the laundry there is always some water that seeps into tiny cracks between the tiles or into the furniture – ideal conditions for mould growth. Have you had your carpet steam-cleaned recently? The moisture in carpets remains for several days, if not weeks, and provides another breeding ground for biological contaminants. Oh, and don’t forget your cat or your dog – a reservoir for allergens.
Some micro-organisms catch a ride in tiny water droplets. Wherever water is dispersed as a fine spray, as in spray humidifiers or even when water bubbles burst in your whirlpool spa, microscopic droplets are propelled into the air. Some may contain bacteria that are harmful when inhaled and can cause dangerous diseases, such as Legionnaires’ disease.
Health Effects of Biological Pollution
We have to live with organisms, but don’t be frightened. Most of the time their numbers are not enough to overwhelm the immune system of a healthy person. Even if they are present in large numbers, not everyone reacts with health problems. But if someone does show symptoms, then they can be the result of an allergic, infectious or toxic reaction. Most at risk are people with breathing problems, such as asthma sufferers, and people with compromised or underdeveloped immune systems, as is the case with sick people or the elderly and the very young.
An allergic reaction to biological contaminants is probably the most common health effect. It may develop after repeated exposure to triggers such as dust mites, animal dander and mould spores. Once the allergy is established, however, the reaction may occur almost immediately.
Common symptoms are:
Congested nose and sinuses
Inflammation of eyes
Shortness of breath
Bacteria and viruses like the indoor air, because there they are likely to find a host where they can multiply and cause infectious diseases in the process. Influenza, the common cold, measles, chicken pox and tuberculosis are just some examples.
Approximately 200 different kinds of viruses cause symptoms of the common cold. Several others lead to influenza. Often, the first signs are sneezing and a sore throat, followed by the inflammation of the sinuses (sinusitis) and the lungs (bronchitis). Fever generally occurs with influenza only. A third kind of virus (Herpes simplex) attacks the weakened human body and causes a cold sore.
These illnesses are most frequent during the colder months of the year. Whenever the person next to you sneezes or coughs, he or she dislodges tiny droplets that contain a large number of viruses. In summer, the fresh air outdoors rapidly dilutes the density of the viruses per given volume and the risk of catching the germ is lower – not so in winter. During the winter months people tend to spend more time indoors with windows closed to save energy. The virus concentration is high and with it comes the risk of inhaling a few.
With every exposure to any of the viruses’ strains, the body develops immunity and protects the person against that particular germ when it appears the next time. The children’s immune system, however, hasn’t had much experience with viruses. It is still learning how to recognize the different strains. Until their body develops the relevant immunities, they will be sick more often. Vaccines induce the body to produce such immunities.
Hypersensitivity pneumonitis and humidifier fever share the same flu-like symptoms, such as fever, headache and chills, and are caused by bacterial or fungal contamination of home heating and cooling systems and of humidifiers. Only meticulous cleaning and disinfection of the equipment is effective in preventing the recurrence of the disease. In both cases, smokers appear to have more serious symptoms than non-smokers.