Recently, the Sterra Moon air purifier has been gaining a lot of attention on social media sites such as TikTok and Instagram. With various Gen Z influencers promoting the use of their air purifiers, the brand has certainly become the talk of the town when it comes to the issue of breathing clean and fresh air. According to their website, the product boasts the ability to kill 99.7% of bacteria and viruses while absorbing formaldehyde, an extremely toxic chemical commonly found in home appliances. 

However, are air purifiers really as effective as they claim to be? Do they really help to provide a clean and safe environment, especially indoors? This blog explores the efficacy of air purifiers in combating air pollution and filtering particulate matter based on scientific research. 

An air purifier is a device that is invented with the purpose of eliminating pollutants from the atmosphere, usually via a combination of filtration and other technologies. These devices can be placed in a variety of settings, from homes to office spaces, and are more productive indoors. Modern air purifiers are typically equipped with High-Efficiency Particulate Air (HEPA) filters (Fig 1) designed to remove 99.7% of dust, pollen, bacteria, and any airborne particles with a size of 0.3 microns (µm).

For instance, the Sterra Moon air purifier adopts a HEPA air filtration technique that first utilizes patented filter fabric to sieve out the largest particles from the air it purifies. Next, the activated charcoal absorbs air contaminants and neutralizes odors. The last layer traps airborne micron particles, thereby decontaminating the environment. 

Fig 1: A diagram illustrating the three-step process behind HEPA filters (Source: Walmart)

Several studies have investigated the viability of air purifiers in improving indoor air quality levels. For example, a study conducted by Dubey, Rohra and Taneja in 2021 compared the number of indoor pollutants removed between air purifiers without HEPA and with HEPA. 

As seen in Fig 2, the HEPA technology is consistently able to lower the concentrations of particulate matter PM10 and PM2.5 compared to devices without HEPA. The study concluded that overall, air purifiers have been observed to abate indoor air pollution, but work better on small-sized particles than large ones. 

Fig 2: Air purifiers with HEPA significantly reduce the concentration of PM10 and PM2.5 for both General Indoor Air (GIA) and in the presence of Candles and Incense Smoke (CIS) (Source: Dubey, Rohra and Taneja, 2021)

Another research performed by Cox et al. found that portable air purifiers equipped with HEPA filters could significantly reduce traffic-related and other aerosols in different residential environments, such as tobacco smoke, PM2.5, and fungal spores by an average of 60%. They are hence particularly necessary for homes situated next to major roads and highways which are constantly exposed to toxic fumes, black carbon and particulate matter. 

However, it is pertinent to keep in mind that the effectiveness of air purifiers varies depending on the specific composition of air pollutants. For instance, HEPA filters are less effective in eliminating VOCs or gases such as nitrogen oxides, which can be around 1000 times smaller than what HEPA filters can capture. According to a study led by MIT researchers,  some portable consumer-grade air purifiers actually remove minimal VOCs and may in fact be producing air that contains additional VOCs and/or oxidation byproducts, thus defeating the purpose of having clean air. 

Additionally, the size of the room, as well as the rate of air flow, are all factors that could hinder the benefits of air filters. Larger-sized rooms require multiple devices to maintain or achieve the desired level of air quality. Despite the numerous potential advantages of air purifiers, we should note that they are not a panacea for air pollution, and should be used in tandem with other measures. 

 

Bibliography

Cox, J., Isiugo, K., Ryan, P., Grinshpun, S. A., Yermakov, M., Desmond, C., . . . Reponen, T. (2018). Effectiveness of a Portable Air Cleaner in Removing Aerosol Particles in Homes Close to Highways. Indoor Air, 28(6): 818–827.

Dubey, S., Rohra, H., & Taneja, A. (2021). Assessing effectiveness of air purifiers (HEPA) for controlling indoor particulate pollution. Heliyon, 7(9): e07976.

EPA. (2022, April 26). What is a HEPA filter? Retrieved from United States Environmental Protection Agency: https://www.epa.gov/indoor-air-quality-iaq/what-hepa-filter#:~:text=It%20is%20an%20acronym%20for,of%200.3%20microns%20(%C2%B5m)

Ham, B. (2021, October 29). Study: Indoor air cleaners fall short on removing volatile organic compounds. Retrieved from MIT News: https://news.mit.edu/2021/study-finds-indoor-air-cleaners-fall-short-removing-volatile-organic-compounds-1029

Sterra. (2023). Sterra Moon™ True HEPA-13 Air Purifier. Retrieved from Sterra: https://sterra.sg/products/sterra-moon?utm_source=google-ads&utm_medium=pmax&utm_source=google-ads&utm_campaign=&utm_agid=&utm_term=&creative=&device=c&gclid=Cj0KCQiAxbefBhDfARIsAL4XLRrfnt8cQEVa2VumOrZBfLv_93DfmVv4ZLQK4FyEbzqsmmJ7G-XdFu0aAhL9EALw_wcB

Ye, Q., Krechmer, J. E., Joshua D. Shutter, V. P., Helstrom, E., Franco, L. J., Cox, J. L., . . . Kroll, J. H. (2021). Real-Time Laboratory Measurements of VOC Emissions, Removal Rates, and Byproduct Formation from Consumer-Grade Oxidation-Based Air Cleaners. Environmental Science & Technology Letters, 8(12): 1020-1025.