When we talk about polluted air, we immediately think of busy streets and industrial fumes. However, polluted air can also be found inside the house due to how we cook, illuminate, furnish, clean or heat the rooms in which we live. Often, in fact, malfunctioning stoves, not good quality candles, fireplaces, cigarette smoke, dry-cleaned clothes, but also new furniture, parquet, the use of glues and cleaning products can be a source of pollutants to which also allergens, molds and pathogenic microorganisms that worsen the quality of the air in the house are added. In addition to internal sources of pollution, however, we certainly must also deal with pollution that comes from outside, especially if we live in the city center or near very busy streets (Das et al, PLoS One, 2021). But exactly, what damage may cause pollution inside homes and offices? And what can we do to improve the air at home? We try to answer these questions based, as always, on scientific research.
The dangers of indoor pollution
Pollution is a health risk since it can cause respiratory tract diseases, such as lung infections, worsen pre-existing conditions such as asthma or persistent cough, and increase the risk of cardiovascular disease and cellular degenerations (Das et al, PLoS One, 2021). It is also believed that exposure to polluting particles, especially fine particulate matter 2,5, can even increase blood pressure, altering the balance of the nervous system by favoring the sympathetic nervous system with a stimulating and exciting function, increasing oxidative stress and by modifying the endothelium, which is the lining of blood vessels (Huang et al, JMIR Public Health Surveill, 2021).
How to improve the indoor air, some small tips
It is certainly important to ventilate the house often, while avoiding the hours of increased traffic in order not to introduce large quantities of particulates inside the house. Then, another ally to improve home air is represented by air filters, which nowadays are able to filter allergens but also pollutants such as particulate matter (Vijayan et al, Lung India, 2015). However, it is necessary to look for good quality air filtering systems that do not release ozone. In fact, the ozone generated by some air purifiers can even worsen indoor pollution, triggering chemical reactions with the terpene, a substance contained in cleaning products, and causing the formation of particles with possible adverse effects on eyes and respiratory system (Norgaard et al, Environ Sci Technol, 2014 - Hubbard et al, Indoor Air, 2005).
How to improve the indoor air, the role of plants
Another system to improve the air of the house is given by plants. Some plants are, in fact, able to remove toxic and carcinogenic substances from the air, such as mercury, formaldehyde, benzene and toluene, essentially in two ways. First, they can metabolize some pollutants and then release other harmless substances, then, they can incorporate toxic substances such as heavy metals into the plant tissue, thus sequestering toxins (Claudio et al, Environ Health Perspect., 2011). It was a large study commissioned by NASA that lasted more than 30 years to focus for the first time on the ability of plants to remove pollutants from the air. Scientist Bill Wolverton, the author of the study, identified a list of just over 50 plants capable of improving the indoor air (Wolverton et al, NASA, 1989). The most powerful plants to improve the air are the areca palm, or chrysalidocarpus lutescens, lady palm, or rhapis excelsa, the bamboo palm, or chamaedorea erumpens, rubber fig, or ficus elastica, the dracaena, the ivy, or hedera helix, the dwarf palm or phoenix roebelenii, but also the fern, which is actually one of the best at removing formaldehyde. Not only that, Spanish moss, or Tillandsia usneoides, has been shown to effectively remove mercury vapors that can be found in the house, for example, following the breakdown of old thermometers (Claudio et al, Environ Health Perspect., 2011). Wolverton also observed that plants' ability to purify air can be significantly improved by increasing the circulation of air near the plant's roots. Therefore, a good choice may be to remove the lower leaves leaving the soil uncovered. In this way, the plant shows a greater ability to remove pollutants since more soil is in contact with the environment (Wolverton, Interior Landscape Plants for Indoor Air Pollution Abatement, 1989).
How to improve the indoor air, it is important to regulate the humidity
A house with a climate that is too dry is certainly not an ideal environment but excessive humidity is also to be avoided. The right humidity to protect health is believed to be between 40 and 60%. In fact, it has been observed that limiting humidity, avoiding excessive values, leads to a decrease in the amount of allergens and molds in the air. Not only that, the release of formaldehyde, a carcinogenic substance, is also linked to humidity (Johnson et al, Allergy Asthma Proc, 2009). In particular, the higher the humidity, the more the release of formaldehyde (Wang et al, Wei Sheng Yan Jiu, 2008).
How to improve the indoor air, essential oils
Some essential oils show powerful antifungal and antimicrobial properties, useful for combating viruses, bacteria and fungi that cause problems in the respiratory system. It has also been shown that, for essential oils, the germicidal action is greater when these act diffused in the air than when they are diluted in solution (Bolashikov et al, Build Environ, 2009). In any case, never exaggerate with the quantity used, just a few drops in an oil burner per room. In fact, essential oils can cause irritation, if in excessive quantities (Bolashikov et al, Build Environ, 2009). Combinations of cypress and tea tree or oregano and tea tree essential oils have been shown to counteract the bacteria responsible for respiratory tract infections. Instead, lemon and sandalwood are excellent at combating fungi and the infections connected to them, while coriander and cinnamon are the most efficient at purifying the air against a wide range of pathogens (Leigh de Rapper et al, Antibiotics, Dec 2021). Excellent antifungal properties are also shown by the essential oils of lemongrass, patchouli, palmarosa and orange, which also has the ability to improve mood and this also helps (Pattnaik et al, Microbios, 1996)!