How do air purifiers help reduce stress?

Scientific interest in the link between air pollution (indoor and outdoor alike) and mental health has grown within the last decade. Studies have begun focusing their efforts on determining the impact of air pollution exposure on brain health, finding that air pollution leads to a variety of psychological disorders including dementia, anxiety, depression, fatigue, and stress. The latter is a subject of growing importance. What is stress? How does air pollution contribute to its onset? How can an air purifier benefit those suffering from stress? Read on to learn more.

What is stress?

Stress is often associated with the feeling of mental tension or worry that is caused by situations that are difficult. More generally, stress is the body’s response to demands that require more effort than usual¹. The feeling of stress is a natural response to everyday life challenges or events that we do not feel able to control or manage².

Everyone has a different relationship with stress and, thus, different symptoms when it occurs. We all experience it to some degree, but for some individuals, it can be a crippling emotion that severely impacts quality of life and longevity.

What are stress hormones?

When a stressful situation occurs, the information is first sent to the amygdala. This is the part of the brain where emotions are processed. Upon interpreting the information, if the brain senses that the situation is dangerous, distress signals (stress hormones) will then be sent to the hypothalamus. Referred to as the brain’s ‘command centre’, the hypothalamus uses the autonomic nervous system to communicate with the rest of the body. The two components of the autonomic nervous system – the sympathetic and parasympathetic systems – balance the body’s ability to react to a stressful situation by initiating ‘fight or flight’ in response to a stressful situation, then ‘rest and digest’ to calm the body back down afterwards³.

What are the main stress hormones sent out by the body? The body releases three main stress hormones: cortisol, epinephrine (adrenaline), and norepinephrine.

• Cortisol: this hormone slows down all non-essential functions when the body is experiencing a ‘fight or flight’ response, like suppressing the digestive system
• Epinephrine (adrenaline): this hormone is released in large amounts in stressful situations, boosting your energy levels by increasing your heart rate and blood pressure and enabling you to ‘flight’ if warranted
• Norepinephrine (noradrenaline): this hormone is released in smaller quantities and increases alertness and vigilance^1,4

Chronic exposure to stress hormones

Long-term exposure to stress hormones, especially catecholamines (which include epinephrine and norepinephrine), impacts many aspects of human health. It may lead to increased risk of anxiety, depression, digestive problems, chronic pain, headaches, heart disease, problems sleeping, and problems with memory and concentration⁴.

PM2.5 and stress

Particulate matter, especially PM2.5, and ozone at home and in the office are considered to be the two airborne pollutants that have the greatest impact on morbidity and mortality. In fact, the Global Burden of Disease estimates that 4.2 million people die every year as a result of particulate matter exposure and 254,000 deaths as a result of ozone exposure.

Air pollution impacts nearly all of the systems in the human body: respiratory (increasing the risk of causing and aggravating respiratory diseases and conditions like allergies), cardiac (increasing the risk of  causing and aggravating heart conditions), reproductive (increasing the risk of infertility), metabolic mechanisms, and neurological, to name a few, though studies suggest that ‘the societal impact of air pollutants may actually be greater than currently appreciated’⁵.

PM2.5’s impact on human stress levels

Recent scientific studies have shown that particulate matter (PM) exposure may act as stressors, causing the body to elicit stress responses. More specifically, high PM2.5 exposure in our indoor and outdoor spaces activates the hypothalamus-pituitary-adrenal and sympathetic-adrenal-medullary axes⁶. Exposure to PM2.5 leads to higher blood pressure, insulin resistance, and other biomarkers of oxidative stress and inflammation amongst participants⁷. This shows that the human body’s central nervous system undergoes changes when exposed to PM.

Another study was performed in 2021 on college-aged students in China. It found that during days of high pollution, students reported a severe prevalence of mental stress. It reported that university students residing in highly-polluted cities were 6.67 times more likely to suffer from severe mental stress⁸. Similar results were reported in a 2019 study on elderly individuals who reported mood changes and higher stress levels when exposed to higher levels of air pollution⁹.

How do PM2.5 and stress affect sleep?

High cortisol levels due to air pollution-aggravated stress impact sleep quality, duration, deep sleep abilities, and ability to fall asleep. Chronic stress also leads to dysregulation of sleep patterns and the sleep-wake cycle, even leading to sleep disorders and sleep-related diseases like sleep apnoea and insomnia. Air pollution (including allergens like pollen and dust, but also PM) also leads to higher incidence of allergies, symptoms of which may further impact sleep quality.

Multiple studies have analysed air pollution (especially PM2.5) in causing poor sleep quality. Higher levels of indoor PM2.5 have been linked to lower sleep efficiency¹⁰. Additionally, a 2021 study found links between indoor air pollution exposure and sleep disordered breathing in children and adolescents¹¹. Another 2019 study observed that air pollution impacts sleep health across all age groups including otherwise healthy, university-aged students¹².

How can medical-grade air purifiers help reduce stress?

The good news is that using a high-quality air purifier to remove indoor air pollution helps significantly reduce stress levels and benefits overall health. Reducing indoor air pollutant particles helps to ease the body’s air pollution-induced stress response.

Reduce levels of stress hormones

Scientific studies have reported that indoor air purification demonstrated short-term reductions in stress hormones, favourably reducing levels of stress in study participants⁶.

Another study found that interventions like incorporating an air purifier to remove airborne pollutant particles, particularly if it contains a HEPA (high efficiency particulate air)-certified filter, can help protect against many adverse health effects caused by air pollution exposure. According to the study, this includes reducing the effects air pollution has on oxidative stress, insulin resistance, blood pressure, and inflammation. Furthermore, an indoor air purifier helps curtail the activation of the sympathetic nervous system and hypothalamic-pituitary-adrenal axis caused by PM2.5, helping to reduce air pollution-induced stress¹³.

It is worth noting that not all air purifiers are capable of cleaning fine particulate matter from the air. Air purifiers equipped with HEPA-certified filters are designed to remove 99.97% of all airborne pollutant particles down to a size of 0.01 microns from your indoor air in a single pass, including unpleasant odours if equipped with an activated carbon filter. Air purifiers with filters that claim to be ‘HEPA-type’, although cheaper, do not guarantee the same level of pollutant removal as they do not undergo third-party testing. All Eoleaf devices contain medical-grade H13 filters as part of our proprietary 8-step filtration method, efficiently removing biological pollution (pathogens and allergens like pollen, dust, and mould spores), chemical pollution (like volatile organic compounds, or VOCs), bad odours, and fine particle pollution.

Enhance sleep quality

Naturally, with lower concentrations of air pollution in your indoor space like your home, flat, or office, your sleep quality will improve. Deeper sleep will be achieved including more rapid-eye movement (REM), high-quality sleep. Additionally, by removing toxic airborne chemicals, allergens (like dust and pollen), and odours from your indoor air, unpleasant health symptoms like allergies and disturbances caused by odours will be reduced, further encouraging better sleep.

The soothing effect of fresh air: white noise

The presence of an air purifier not only improves overall well-being, but a bonus feature of an air purifier in the home is its ability to act as a white noise machine. Studies have shown that white noise machines reduce the time it takes to fall asleep by 40% for healthy individuals and also helps babies and children fall asleep more quickly^14,15. To reiterate, better, longer sleep leads to lower stress levels.

The Eoleaf difference

We at Eoleaf put your health first. By investing in an air purifier to reduce indoor pollutant and airborne chemical concentrations, you are investing in your overall health (especially your respiratory and cardiac health). Reach out to our team of air quality experts with any questions you may have. Also refer to our in-depth Buying Guide to find the Eoleaf device that is perfect for your needs.

Frequently asked questions

Are there specific pollutants or allergens that air purifiers remove which are known to increase stress?

Studies are showing that particulate matter, specifically PM2.5, has been linked to higher stress levels. PM2.5 exposure leads to higher blood pressure, insulin resistance, and other biomarkers of oxidative stress and inflammation. This was further demonstrated in a 2021 study on college-aged students in China who were 6.67 times more likely to suffer from severe mental stress when living in areas with high air pollution levels.

How does the noise level of air purifiers affect stress?

An air purifier should not be noisy. Eoleaf prides itself on offering quiet air purifiers that never exceed 60 dB of noise, even when set on their highest fan speeds. When left running on lower speed levels, Eoleaf devices are nearly silent. An air purifier’s sound level should never disturb a room’s occupants.

Is there scientific evidence supporting the claim that air purifiers reduce stress?

Yes! Scientific studies have reported that indoor air purification provides short-term reductions in stress hormones, favourably reducing levels of stress. Furthermore, studies have shown that HEPA-certified air purifiers help reduce the effects air pollution has on oxidative stress, insulin resistance, blood pressure, and inflammation.

What are the psychological benefits of using air purifiers?

In addition to reducing stress levels, the use of air purifiers has been shown to improve focus and concentration, decrease the risk of experiencing mental health disorders like anxiety and depression, and reduce fatigue. Furthermore, for those suffering from respiratory diseases like asthma or COPD, air purifiers have been proven to help reduce symptoms of those diseases, providing an overall improved psychological and physical well-being.

Are there specific features in air purifiers that are more effective in stress reduction?

Yes. Since particulate matter (especially PM2.5) has been most heavily linked to increased stress levels, it is important to invest in an air purifier that is capable of removing PM. The only air purifiers that are guaranteed to do so are HEPA-certified air purifiers which remove 99.97% of all air pollutants down to a size of 0.01 microns in a single pass. All Eoleaf devices contain medical-grade HEPA H13 filters.

Is it OK to sleep with an air purifier?

Absolutely! Certain air purifiers, like Eoleaf’s, are equipped with a Night mode setting. This keeps the device running at its near-silent, lowest fan speed with all the indicator lights shut off. This ensures that you will continue to breathe purified air whilst you sleep, all without being disturbed.

Do air purifiers help with depression?

Studies have shown that long-term exposure to air pollutants – particularly nitrogen dioxide (NO2), nitric oxide (NO), and particulate matter (PM) – leads to an increased risk of depression and anxiety. The pathway by which this happens is still misunderstood: some studies suggest that air pollution affects the central nervous system whereas others point more towards the blood-brain barrier. Additionally, exposure to particulate matter (PM) causes inflammation and irritation in organs throughout the body, leading to respiratory disease (and aggravation of respiratory conditions such as asthma), various cancers, stroke, and heart attack.

Resources

¹ BodyLogicMD. (2022, December 20). What are stress hormones and how do they impact you?. BodyLogicMD. https://www.bodylogicmd.com/blog/what-are-stress-hormones/

² World Health Organization. (2023, February 21). Stress. World Health Organization. https://www.who.int/news-room/questions-and-answers/item/stress

³ Understanding the stress response. Harvard Health. (2020, July 6). https://www.health.harvard.edu/staying-healthy/understanding-the-stress-response

⁴ Mayo Foundation for Medical Education and Research. (2023, August 1). Chronic stress puts your health at risk. Mayo Clinic. https://www.mayoclinic.org/healthy-lifestyle/stress-management/in-depth/stress/art-20046037

⁵ Thomson EM. Air Pollution, Stress, and Allostatic Load: Linking Systemic and Central Nervous System Impacts. J Alzheimers Dis. 2019;69(3):597-614. doi: 10.3233/JAD-190015. PMID: 31127781; PMCID: PMC6598002.

⁶ Li H, Cai J, Chen R, Zhao Z, Ying Z, Wang L, Chen J, Hao K, Kinney PL, Chen H, Kan H. Particulate Matter Exposure and Stress Hormone Levels: A Randomized, Double-Blind, Crossover Trial of Air Purification. Circulation. 2017 Aug 15;136(7):618-627. doi: 10.1161/CIRCULATIONAHA.116.026796. Erratum in: Circulation. 2017 Sep 12;136(11):e199. PMID: 28808144.

⁷ Li, H., Cai, J., Chen, R., Zhao, Z., Ying, Z., Wang, L., Chen, J., Hao, K., Kinney, P. L., Chen, H., & Kan, H. (2017). Particulate matter exposure and stress hormone levels. Circulation, 136(7), 618–627. doi:10.1161/circulationaha.116.026796

⁸ Zhang, W., Peng, S., Fu, J., Xu, K., Wang, H., Jin, Y., Yang, T., & Cottrell, R. R. (2021). Urban air pollution and mental stress: A nationwide study of university students in China. Frontiers in Public Health, 9. doi:10.3389/fpubh.2021.685431

⁹ Nuyts V, Nawrot TS, Scheers H, Nemery B, Casas L. Air pollution and self-perceived stress and mood: A one-year panel study of healthy elderly persons. Environ Res. 2019 Oct;177:108644. doi: 10.1016/j.envres.2019.108644. Epub 2019 Aug 9. PMID: 31421443.

¹⁰ Horvath, E. (2023, April 18). Study links air pollution, heat, noise & more to reduced sleep - penn medicine. Study Links Air Pollution, Heat, Noise & More to Reduced Sleep - Penn Medicine. https://www.pennmedicine.org/news/news-releases/2023/april/sleep-efficiency

¹¹ Liu J, Wu T, Liu Q, Wu S, Chen JC. Air pollution exposure and adverse sleep health across the life course: A systematic review. Environ Pollut. 2020 Jul;262:114263. doi: 10.1016/j.envpol.2020.114263. Epub 2020 Feb 24. PMID: 32443219; PMCID: PMC7877449.

¹² Yu H, Chen P, Paige Gordon S, Yu M, Wang Y. The Association between Air Pollution and Sleep Duration: A Cohort Study of Freshmen at a University in Beijing, China. Int J Environ Res Public Health. 2019 Sep 11;16(18):3362. doi: 10.3390/ijerph16183362. PMID: 31514480; PMCID: PMC6766077.

¹³ Brook, R. D., & Rajagopalan, S. (2017). “Stressed” about Air Pollution. Circulation, 136(7), 628–631. doi:10.1161/circulationaha.117.029688

¹⁴ Messineo L, Taranto-Montemurro L, Sands SA, Oliveira Marques MD, Azabarzin A, Wellman DA. Broadband Sound Administration Improves Sleep Onset Latency in Healthy Subjects in a Model of Transient Insomnia. Front Neurol. 2017 Dec 21;8:718. doi: 10.3389/fneur.2017.00718. PMID: 29312136; PMCID: PMC5742584.

¹⁵ Spencer JA, Moran DJ, Lee A, Talbert D. White noise and sleep induction. Arch Dis Child. 1990 Jan;65(1):135-7. doi: 10.1136/adc.65.1.135. PMID: 2405784; PMCID: PMC1792397.