Introduction

Wheezing is a high-pitched sound which can be produced by individuals with asthma, heart failure, or airway obstructions when they breathe in or out.¹ It occurs when the airways become narrow, which can be caused by different reasons. Wheezing can be due to inflammation of the airways in asthma and allergy, or the presence of a mass blocking them, such as a tumour or aspiration of foreign bodies.¹ A decrease in the speed at which the air flows in the airways produces rapid vibrations in the latter, which are heard in the form of a wheeze.¹

Wheezing is more prevalent in children compared to adolescents and adults (26% vs. approximately 12%).¹

Wheezing often manifests following an exposure to certain triggers. People with the aforementioned conditions are more sensitive to these triggers and hence more prone to experience episodes of wheezing, which are often accompanied by difficulty in breathing.

Environmental factors are the most common form of triggers of this symptom and can be subdivided into three categories, which are indoor, outdoor, and occupational triggers.

Being aware of these triggers allows sensitive people to determine which ones affect them the most, in order to avoid them and reduce their chance of being wheezy.

Indoor environmental triggers

Many people may be exposed to certain elements within the comfort of their households or workplace, which can irritate their airways. Below, we list some of the most common indoor irritants that sensitive people should look out for and try to eliminate when found.

Dust mites and household dust

Dust mites are very tiny creatures that live in every house and are not visible to the naked eye. They thrive in humid and warm conditions and feed off dead skin cells that humans shed. They are found mainly in bedding but also in carpets, clothing, upholstery and curtains. Their droppings are the cause of dust mite allergy because of certain proteins they contain.

Exposure to dust mites can be reduced, though not fully eliminated, by practising some hygiene measures regularly. Washing the beddings every week at high temperatures of 60°C or above kills the dust mites. Carpets should be avoided where possible, and if not, then they should be vacuumed at least once a week. The furniture should also be wiped down with a damp cloth to remove mites and their faeces. The house should be well aired and ventilated, and the use of dehumidifiers is also recommended to reduce indoor humidity below 50% so that the environment is less favourable for mites.

Mould and mildew

Mould is a type of fungus that grows in humid and damp conditions both indoors and outdoors. They are usually found on dead leaves and tree logs, and in bathrooms and kitchens in the house as they are usually humid and poorly ventilated.

It reproduces by releasing spores that float in the air, and which trigger an allergic reaction if they are inhaled. This is particularly more significant in individuals who have asthma or allergies, as their body’s reaction will be more pronounced.

Mildew is also a type of mould.

Knowing that mould grows best in wet and damp areas allows people to take some precautions to prevent it or eradicate it when it occurs.

Bathrooms and kitchens should always be checked for signs of mould, and when found, they should be removed using proper detergents and water. It is recommended that protective equipment, such as gloves, masks, and goggles, be worn to prevent inhalation of the spores when the mould is being removed. Bathrooms should ideally be ventilated during showers and for at least 15 minutes afterwards. Indoor humidity should also be monitored and reduced by using dehumidifiers if it exceeds 50%.

Maintaining good air flow in the house and tending to any leaks as soon as they happen are also important measures to curb mould infestations.

Pet dander

Many people are allergic to animals and pets, and around 10% to 20% worldwide have an allergy to dogs and cats.

The allergy is not caused by the animals’ fur but rather by a protein found in their urine, saliva, and dead skin cells, which are referred to as pet dander. When these proteins are in contact with the person’s airways, nose, or eyes, they may cause irritations and trigger an allergic reaction in sensitive individuals.

Pets can also carry another allergen, such as pollen or dust mites, on their skin and hair, which might further worsen the allergic reaction. This effect may last up to 6 months after the pet has been removed from the house.

The decision to keep a pet at home despite being allergic depends on how severe the allergy is. If the allergy is mild and can be managed by using allergy treatments like nasal sprays and antihistamines, some measures can be followed to reduce its severity. These include keeping the pets and their belongings outside of bedrooms, and showering and washing clothes after playing with them. Carpets and fabric furniture should be avoided where possible and, if not, vacuumed and cleaned on a weekly basis. All surfaces need to be wiped with a damp cloth, and an air purifier should be used for at least four hours daily to clean the air. The pet should also be washed at least once weekly to remove any dander or other irritants on their skin.

If the pet allergy is severe, the pet should be rehomed and the house thoroughly cleaned to rid it of dander, which might still remain for up to 6 months.

Tobacco smoke

Smoking is universally known as a common cause of preventable death. This is not due to the nicotine present in the cigarettes, but rather the other chemical products that enter in the making of tobacco, a lot of which are poisonous. Examples of these are arsenic, cyanide and formaldehyde.⁶ Smoking destroys the lungs, which are already under a lot of strain in individuals with asthma and other airway conditions. It causes irritation of the airways, which may further worsen wheezing. Breathing in tobacco smoke from being around a smoker, known as second-hand smoking, also worsens this symptom and is quite harmful as the person is breathing in the chemicals released in the smoke.⁶

Sensitive individuals who are smokers should try quitting smoking on their own or seek medical help, through the use of nicotine replacement therapy, to stop using tobacco. Non-smokers should also avoid being around anyone who smokes or being in spaces where smoking has just taken place by others.

Volatile organic compounds (VOCs)

Volatile organic compounds are compounds that are released into the air and do not dissolve in water easily. They come from many products and industrial processes. They are released from many products such as paints, cleaning supplies, gasoline and pesticides.

Breathing these substances in can be very harmful and trigger allergic reactions and wheezing. Some VOCs have also been found to be carcinogenic. Some common VOCs are trichloroethylene, which is a carcinogenic industrial solvent, chloroform, and formaldehyde.

In order to minimise the effects of VOCs on health, individuals should look for products with the “low VOC” label when shopping, and if not available, they should only buy an amount that suffices for the job they need them for, to avoid having leftover products. Manufacturers’ instructions should be properly followed in regard to the appropriate use and disposal of VOC-containing products.

Ensuring houses are ventilated when VOCs are being used is also necessary to avoid their harm.

Outdoor environmental triggers

Pollen and seasonal allergens

Wheeze is a common symptom of allergy, for which pollen is a well-known irritant. Therefore, individuals with allergies experience an increase in this symptom during seasons when pollen count is high. Pollen is classified into three categories, whether it originates from trees, grass or weeds, and these types of pollen are present at different times of the year. In the UK, the tree pollen season spans from late March to mid-May, whereas the grass and weed seasons are from mid-May to July and end of June to September, respectively.

Pollen is released into the air in the form of small particles, which the wind carries around to fertilise other plants of the same species. However, this pollen can often be inhaled or enter the eyes of humans, and this triggers an allergic reaction.

Sensitive individuals who suspect they might be allergic to pollen can have this confirmed based on a detailed medical history alongside an allergy prick test or a blood test to check for antibodies against pollen.

The weather forecast includes a section for the daily pollen count, which individuals should check regularly to avoid going outside when the count is high. It is also useful to know the season in which each type of pollen is prevalent to avoid exposure or to take allergy medications before the beginning of the season. It is also recommended to close windows during peak times and cover the eyes and nose while outside, and to remove shoes and shower once back home to remove any pollen that might have been carried by the person.

Air pollution and smog

Living in an industrialised world exposes people to many air pollutants that are detrimental to their health. Fumes and emissions from vehicles contain nitrogen dioxide and sulphur dioxide, which are common irritants. Ozone is another common trigger; it is known to be harmful when found at ground level. It is part of smog, which is smoke found in haze or fog, and is linked to fuel emissions and heat. All these pollutants harm the lungs and airways when inhaled, especially by asthmatics.

Cold air and weather changes

Cold air is known to irritate the airways and may also cause them to become narrow, which makes wheezing more prevalent and breathing more difficult. This can be managed by wearing face masks or a scarf around the mouth and nose whenever going out.

Occupational environmental triggers

The person’s workplace often puts them in direct exposure to certain products that may cause allergic reactions. Breathing in chemical fumes, containing ammonia or chlorine, for example, and dust can irritate the airways. Dust can also accumulate in the lungs and cause serious illnesses like pneumoconiosis.

People working in farms and with livestock are exposed to organic dust composed of animal and plant fragments, bacteria, fungi and pollen.¹² The inhalation of this organic dust can also irritate the lungs and worsen asthma, even promoting the development of chronic respiratory diseases.¹²

Conclusion

Wheezing is a common symptom in people with health conditions affecting their airways. It may be triggered or worsened by many environmental factors, both indoors and outdoors. A person’s occupation and workplace can also expose them to more irritants that contribute to their wheezing. Common indoor pollutants include dust mites, mould, pet dander, tobacco smoke and volatile organic compounds from paints and detergents.

When going outside, sensitive people should look out for triggers like a high pollen count, air pollution, and cold and dry weather. These factors can all be found in weather forecasts on a daily basis, so it is worth finding a reliable one to check out regularly.

Common workplace environmental triggers include chemical fumes and dust, both organic and inorganic.

It is crucial to be able to identify which irritants trigger a wheeze or worsen it for sensitive individuals. This will allow the person to look out for them and limit their exposure, thus reducing their chance of an allergic episode.

Once triggers are identified, the preventive measures mentioned above are quite useful in reducing the presence of the allergens or eradicating them completely. Hence, it is highly recommended that people follow them regularly and not just sporadically to guarantee their effectiveness.