Allergic Rhinitis: Reducing Allergen Exposure in a Changing Environment
With allergic rhinitis (sometimes called hay fever), the environment around you is just as important as your anatomy. Scientists have a term for all of the environmental factors that surround you throughout your life – the “exposome”. For those suffering with allergies, the exposome includes the overall environment and the micro-environment (your personal, close-up environment) including allergens, irritants and air pollution.
Allergic rhinitis is caused by exposure to seasonal and perennial allergens in susceptible individuals. Seasonal allergens are represented by tree, grass and weed pollens. Symptoms occur when levels of these pollens are elevated. On the other hand, perennial allergens are responsible for allergic rhinitis symptoms year-round. The most common perennial allergens are dust mites, cockroach, mice, rats, molds and pets. A large proportion of allergic patients have perennial allergic rhinitis with seasonal exacerbations because of allergies to multiple environmental allergens, both seasonal and perennial.
Irritants (such as strong smells, cleaning products, perfumes, smoke, car exhaust), physical activity or sudden changes in temperature (e.g., going from a warm room to cold weather outside), can also cause nasal symptoms. These non-allergic stimuli cause inflammation and an irritative response in the nasal passages, resulting in rhinitis symptoms.
Exposure to aeroallergens and irritants can lead to chronic airway inflammation. This is why reducing contact with the allergen or irritant is a necessary part of treatment. However, there are times when it’s difficult to control the environment around you. Mechanical barriers such as masks, nasal filters and air purifiers are needed to prevent exposure to aeroallergens and irritants, particularly when one cannot stay indoors during the heavy pollen season.
• A mask is a covering fitted over the nose and mouth that blocks particles in the air like allergens, pollutants and viruses. Studies have shown wearing a face mask may also reduce rhinitis symptoms by altering the humidity and temperature of breathed air. There are many types of masks available on the market. Standard surgical masks filter particles bigger than 3 μm (micrometers), whereas N95 respirators can filter particles as small as 0.04 μm. Therefore, using either face mask will reduce exposure to the common allergens such as pollens (10-100 μm), fungal spores (2-50 μm), and house dust mites (10-40 μm).
• A nasal filter is a barrier using a fibrous or porous mesh designed to fit closely inside the nostrils and filter allergens from the inhaled air. It may have a role in situations of high allergen exposure.
• A HEPA (high-efficiency particulate air) air purifier contains a type of mechanical air filter that works by forcing air through a fine mesh. It is a portable device that you can use in an indoor space to trap and reduce unwanted aerosolized particles such as pollen, pet dander, dust mites, and tobacco smoke in the air you breathe. However, air purifiers are not efficient in removing settled allergens on the surface of furniture, walls or floors.
We also must consider an evolving environment when assessing the risk for future aeroallergen exposure. Climate change is agreed on by all the major scientific societies and professions. With the changing climate, pollen seasons are starting earlier, evidenced by earlier tree pollen blooming in the eastern part of the United States, and lasting longer in length. Average daily pollen count has increased over the past 25 years and is projected to increase further in the coming decades. In addition, plant species, such as Bermuda grass, have been extending northward, exposing a greater number of people to this unique grass pollen.
Air pollution exposure in early childhood has been associated with the development of allergies to pollens and animal dander as well as a greater likelihood of developing asthma. Air pollution has also been shown to increase asthma and hay fever symptoms and exacerbations.
When thinking about allergies, environmental avoidance measures are important to treat the underlying cause. As the climate is changing, allergy seasons are becoming more intense and measures to reduce exposure, such as masks, nasal filters and air purifiers, are helpful in treating allergies. Knowledge of your personal allergy profile through allergy testing can help you modify your environment to reduce your personal exposure to allergens and irritants.