What Are Biological Aerosols and How Do They Affect Indoor Air Quality?

Biological Aerosols

Biological aerosols, or bioaerosols, include all kinds of microorganisms including bacteria, viruses, mold, fungi, insects, pollen, and pet dander as well as cellular fragments, spores, fungal hyphae or by-products of microbial metabolism. These bio particles are released from terrestrial and marine ecosystems and can be found traveling through the atmosphere and also on surfaces.

Whilst some microorganisms may play beneficial roles, many can be seriously harmful to people. In particular, some bioaerosols behave as a biological pollutant, and are a major contributor to poor indoor air quality. Here’s how bioaerosols can reduce air quality and cause issues such as allergies, asthma attacks, and respiratory discomfort and infections.

What are biological pollutants?

Biological pollutants are dander, skin flakes or microorganisms, including their parts or products of their metabolism, that are typically small and can be inhaled easily, and that can be harmful to humans. The US EPA covers a full list of sources of biological pollutants, which includes:

  • Bacteria and viruses, some of which live and travel through the air causing respiratory diseases such as pneumonia or tuberculosis, and other types can be carried by animals and people or found in plant debris and soil.
  • Household pets and homestead animals can shed animal dander (skin flakes), hair (fur and feathers), and also spread pollutants via their feces, urine, and saliva.
  • Mold is often the unknown cause of many health issues. It is a pathogen that thrives in damp conditions and is typically found in damp corners of bathrooms and kitchens. Mold is particularly harmful and is also a silent threat, as it releases spores into the atmosphere which can travel throughout the home, causing mold patches to emerge in other rooms. These spores also aggravate sinuses and can trigger allergies and asthma flare-ups. Mold, yeast, and mushrooms are part of the fungi family, and any unwanted and unplanned fungi growths indoors can pose a threat to human health.
  • Pests and insects can shed skin, leave droppings, and create bacteria havens with rotting carcasses and remnants of body parts. A certain protein found in rats’ urine can become airborne once the urine has dried. This protein is recognized as a strong allergen that can be very harmful to humans.
  • Pollen from plants and trees, grown indoor or outdoor, can become airborne and become an allergen for pets and people.

Many of these sources of biological pollution transform into bioaerosols, which can do just as much harm to humans as their source can. Whilst many cleaning products target signs of physical dirt such as dust, droppings, mold, and pollen, the cleaning products do not necessarily remove all airborne contaminants.  Consequently, many harmful particles can still remain in the air. These invisible biological contaminants cannot escape spaces that appear to be well-ventilated by air conditioning systems, but are in fact trapping harmful airborne particles in closed indoor spaces.

How does biological contamination harm people?

Households, and crowded places with airborne biological pollutants may notice a distinctive decline in health and wellbeing of the occupants of those spaces. From mild irritations to their sinuses to the extremes of cancer diagnosis, the list of symptoms range from causing minor irritation to triggering or causing life-threatening illnesses. Biological pollutants can cause:

  • Acute toxic effects can cause damage to the liver, digestive system, and the immune system and can lead to long term illnesses and irreversible harm.
  • Allergic rhinitis, more commonly known as hay fever and often identified as general allergies to certain allergens including dust mites, pet dander, and aerosols, can cause swelling around the eyes, itchy nose and eyes, blocked sinuses, runny noses, and sneezing.
  • Asthma, although not all types of asthma are the result of biological factors. Asthma sufferers may experience flare-ups or attacks, during which they may encounter breathing difficulties, bronchospasms, and may require an inhaler to alleviate shortness of breath and feelings of tight-chestedness.
  • Cancer, specifically lung cancer, has been found to increase in individuals exposed to indoor air pollution, according to one study. Another study highlights that nasopharyngeal cancer is also strongly associated with pollution.
  • Cystic fibrosis can be aggravated by poor indoor air quality. One study indicated an increased risk of death for individuals with cystic fibrosis who are exposed to indoor air pollution.
  • Diseases from animal feces are also possible: mouse droppings carry various pathogens, including hantavirus, leptospirosis, lymphocytic choriomeningitis virus and salmonella.
  • Hypersensitivity pneumonitis, also called extrinsic allergic alveolitis, is a form of pulmonary fibrosis caused by the repetitive inhalation of antigens.
  • Infectious diseases such as flu, chicken pox, measles, and tuberculosis are all caused by bacteria and viruses that can be airborne.
  • Neurological effects can result in damage to the central nervous system, with studies linking indoor air pollution to poorer cognitive performance.
  • Undiagnosed illnesses, which is something many doctors encounter every year. Patients present with symptoms of coughs, headaches, rashes, and fatigue, and medical professionals cannot identify the causes. The reality is that many of these symptoms are thought to be triggered by bioaerosol contaminants found indoors. These health issues can last for years and eventually lead to serious health concerns, with doctors continuing to struggle to identify the cause. Recent cases of mold causing death to young children highlight the serious risk of indoor contaminants to peoples’ health.

Additionally, pets can suffer from allergies and reactions to airborne pollutants too.

How do biological pollutants impact air quality?

With a host of possible biological pollutants produced by plants, pets, and people, it is highly likely that these pollutants will become airborne and impact the quality of the air. With prolonged exposure, even healthy individuals may find themselves with symptoms of various health issues, such as sneezing, coughing, dizziness, headaches, and digestive problems. There is no doubt that these biological contaminants can drastically reduce the quality of air, both indoors and outside. Without correct ventilation, air pollutants can become trapped in homes and offices, resulting in permanently low air quality.

Mold poses a particular threat to indoor air quality, because of its ability to spread between rooms via the spores through the air. Spores can grow in warm damp areas, for example in a bathroom, and then release into the air and travel around the home or commercial space. They then colonize a new area of the indoor space, and release further spores, continuing the cycle. These mold spores irritate respiratory systems of both people and pets, and can present a serious health risk.

How can indoor air quality be improved?

In the past, targeted approaches focused on issues thought to be the main cause of indoor pollution. For example, droppings caused by rodents would be resolved with the help of pest control, or a child suffering from asthma might be medicated, and may have their bedroom retrofitted to remove carpets to try to alleviate symptoms. However, it is now understood that maintaining good quality air indoors requires a multi-faceted approach. Even in the cleanest of houses and offices, these indoor spaces that are sealed off from the outside world can still be an unhealthy environment for humans.

This is because indoor spaces increasingly rely on ventilation systems to circulate air and manage room temperature. Bioaerosols and biological pollutants are becoming trapped in these indoor spaces. The Covid pandemic was a reminder as to how quickly viruses can spread between humans, especially indoors. The virus is one of many viruses, bacteria and other airborne biological pollutants that pose a threat to human health.

Regular ventilation of houses and offices may be suitable in some cases and when the weather permits. In some parts of the world, opening windows and doors to help ventilate indoor spaces simply opens them up to other airborne pollutants, such as pollen and air pollution.

One of the best solutions is to purify indoor air with a technology that actively works to identify, capture, and remove toxic pollutants and allergens circulating in residential and office spaces.

Air purification devices can improve indoor air quality

As air pollution and biological contamination continues to threaten inhabitants of indoor spaces, air purifiers offer one of the most effective solutions to bring clean, pure air into homes, schools, work-places and hospitals. Research continues to highlight the dangers of bioaerosols and the number of pathogens trapped indoors, air purifiers offer an effective solution for improving indoor air quality.

What is an air purifier?

There are different types of air purifiers used today, with some models using mechanical filtration, some using UV light, and others using chemicals to neutralize pathogens. Some of the latest technology also uses hydrogen peroxide, which is an active biocide that neutralizes pollutants in the air.

Air purifiers that use filtration systems draw air through a filter to remove specific molecules from the air. They then blow the filtered air back out into the area. Air purifiers that provide chemical neutralization release active molecules, sometimes called “radicals” or “ions”. These float about the indoor air space and when they come into contact with other pathogens in the air, efficiently remove them by neutralizing them, or altering their chemical compounds so that they are no longer harmful. Chemical treatment of indoor air is safe for people, so much so that the technology can operate without requiring any vacation of the premises. The technology produces active molecules that are commonly found in the air and are harmless to humans. Occasionally, some byproducts of technology can be harmful to humans in certain quantities, and regulators have already put in place requirements to keep people safe.

Many popular solutions today are available as “add-ons” that can be retrofitted to existing air conditioning units. These devices transform A/C systems into efficient air purifiers, leveraging the HVAC systems’ airflow to chemically treat the air in the conditioned space.  Examples of air purifiers include the TADIRAN AIROW 1™ for ducted HVAC systems and the TADIRAN AIROW 3™ for wall-mounted air conditioners.

Can some air purifiers proactively clean the air?

Yes. Many air purification devices work on the premise that air must be sucked or drawn through their filtration systems. Most systems require electricity to operate the filtration systems; they need to be switched on to actively pull air through the filters, neutralize any toxins, and pass fresh air back out into the local environment.

Tadiran’s AIROW 1™ for HVACs and Tadiran’s AIROW 3™ for wall-mounted air conditioners  both use a more proactive approach. Instead of drawing air through their systems, they produce hydrogen peroxide. This chemical compound is emitted into the atmosphere air and when once it encounters pathogens, it neutralizes them safely. This method of tackling indoor pollution is much more effective than a passive approach for 3 reasons: it is quickly moved around the conditioned space with the airflow generated by the air conditioner; it is an active neutralizer; and it doesn’t produce any dangerous byproducts.

What is the effect of air purification on biological pollution?

Just like pest control helps remove unwanted visitors, air purification helps remove unwanted airborne particles that could harm human health. Air purification technology can be used in residential and commercial spaces and can be programmed to constantly purify air, creating safe and healthy environments for employees and families.

Filtration-based purifiers remove aerosols via mechanical separation, while hydrogen peroxide or hydroxyl based purifiers act as air disinfectors, via biocide agents that are released into the air and directly tackle bioaerosols that are harmful to people.

The effects of an air purifier include a drastic reduction in dust pollution, as well as the removal of around 99% of pollutant particles. HEPA filters can remove 99.97% of particles that are as small as .3 microns, eliminating biological contaminants from indoor spaces and preventing illnesses from biological pollution. However, many viruses and bacteria are much smaller, and so these solutions with filters are mainly limited to removing dust particles from the air. Purification devices by Tadiran, including the TADIRAN AIROW 3™ are proven to be effective against pathogens. Tests show that after just one hour of use, the presence of harmful molecules of the SARS-CoV-2 was reduced by 99.93%. This testing was conducted in the US-based laboratory Innovative Bioanalysis, which is BSL3 accredited.

Are some air purifiers more effective than others?

Although there is no all encompassing test that can help to answer this question, it is worth noting that many air purification systems require some form of maintenance to keep them operating effectively. In many instances, systems that use UVC-LED,, and filters, UV and hydroxyls, will all require some kind of maintenance after a period of time. The risk here is that where this maintenance isn’t carried out, the air purification systems’ effectiveness declines sharply.

Additionally, many air purification systems that either passively operate (drawing particles through a filter) or actively operate (emitting neutralizing compounds into the area) may not cover the areas required. As explored above, passive operating devices may never reach all the different air pockets of indoor spaces. More active air purification devices need to be able to cover reasonably large indoor areas, in order to be effective.

The TADIRAN AIROW 3™ can be retrofitted, and is a small, non-invasive device that covers large areas with a proactive, human-safe method of air purification. Tests show that within just 60 minutes of use, Tadiran’s AIROW 3™ substantially reduces bioaerosols from the air, including:

  • 99.93% reduction in the COVID Virus in a 16m3 chamber
  • 99.994% reduction in the RNA Virus MS2 Bacteriophage in a 1m3 chamber
  • 99.994% reduction in the bacteria Staphylococcus Epidermis in a 1m3 chamber

Additionally, tests showed a 99.4% reduction in Aerosolized Blue Mold (Penicillium Citrinum) in a 25m3 chamber after just three hours. View detailed test results for the TADIRAN AIROW 3™ here.

Air purification technology can proactively improve air quality indoors

By producing an active molecule that can efficiently neutralize harmful airborne pollutants, proactive air purification devices can make a big improvement to indoor air quality. The TADIRAN AIROW 3™ is a proactive solution for combatting airborne biological pollutants indoors and simultaneously raising indoor air quality. Discover more about Tadiran’s latest air purification device.

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