Special concern on COVID-19 Aerosol Drivers, Impacts and also Mitigation (X)Details 2021 - Volume 21 Volume 21, problem 2, February 2021 07 October 2020 Reach: 67040

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You are watching: Does wearing a mask cause you to breathe in carbon dioxide

European Commission, Joint research study Centre (JRC), Ispra, Italy


Download Citation: RIS|BibTeX|https://doi.org/10.4209/gendergeek.org.2020.07.0403 

mention this article: Geiss, O. (2021). Effect of Wearing face Masks ~ above the Carbon Dioxide Concentration in the breathing Zone. Aerosol waiting Qual. Res. 21, 200403. Https://doi.org/10.4209/gendergeek.org.2020.07.0403


Concentration of CO2 in the breathing zone if wearing a confront mask to be determined.Three varieties of confront masks to be tested under different conditions.The measure up concentrations have no toxicological effect when inhaled. 


The use of face masks is among the procedures taken to protect against person-to-person infection of the virus (SARS-CoV-2) responsible because that the coronavirus an illness (COVID-19). Lately, problem was expressed about the opportunity that carbon dioxide could construct up in the mask over time, leading to medical worries related to the respiratory tract system. In this study, the carbon dioxide concentration in the breathing zone to be measured if wearing a surgical mask, a KN95 and a cloth mask. For the operation mask, the concentration was established under different problems (office work, slow walking, and also fast walking). Dimensions were made making use of a modified at home air high quality meter equipped v a nondispersive infrared (NDIR) CO2 sensor. Detect carbon dioxide concentrations ranged from 2150 ± 192 to 2875 ± 323 ppm. The concentration of carbon dioxide while no wearing a challenge mask differed from 500–900 ppm. Act office work and also standing still on the treadmill each resulted in carbon dioxide concentrations of approximately 2200 ppm. A tiny increase might be observed as soon as walking at a rate of 3 kilometres h–1 (leisurely go pace). Walking at a speed of 5 kilometres h–1, which corresponds to medium task with breathing with the mouth, caused an typical carbon dioxide concentration that 2875 ppm. No differences were observed amongst the three species of challenge masks tested. According to the literature, these concentrations have actually no toxicological effect. However, concentration in the detected variety can cause undesirable symptoms, such together fatigue, headache, and loss that concentration.

Keywords: challenge masks, Carbon dioxide, SARS-CoV-2, COVID-19 pandemic, COVID-19


Physical distancing, great hand hygiene and also the attract of gloves and also face masks are amongst the most regular measures take away to stop person-to-person transmission of the virus (SARS-CoV-2) responsible because that the coronavirus disease (COVID-19) since the outbreak that the COVID-19 pandemic in early 2020 (Chu et al., 2020; Howard et al., 2020). Especially, the usage of challenge masks in windy reduces the spread of the virus by minimizing the excretion of respiratory droplets from asymptomatic infected people or people who have not yet occurred symptoms (Bourouiba, 2020). The human being body utilizes oxygen and also generates carbon dioxide, i beg your pardon is then exhaled in the expiration air. An adult with healthy and balanced lungs produces around 5.6% by volume that CO2. As soon as wearing a face mask, a fraction of carbon dioxide previously exhaled is inhaled again v each respiratory tract cycle. Some media have actually been claiming the carbon dioxide might slowly develop up in the mask end time, leading to medical concerns related to the respiratory system such as hypercapnia (a condition arising from too lot carbon dioxide in the blood).

Only a few studies have been performed so far in this field. In a study conducted by Sinkule et al. (2013), the breath air quality as soon as using N95 filtering facepiece respirators was assessed. The concentration of carbon dioxide enhanced to around 1.2–3% in a short duration of irradiate work. The participants did no show any kind of obvious changes in physical functions. The average carbon dioxide concentration inhaled was, however, far greater than the border of 0.1% of indoor carbon dioxide concentration in many countries. The research of Li et al. (2005) investigated the effects of put on N95 and surgical challenge masks with and also without nano-functional therapies on thermo-physiological responses and also the spatu perception of uncomfortable in 5 healthy participants (men and women). They discovered that surgical confront masks were rated substantially lower for perceptions of humidity, heat, breath resistance and overall discomfort 보다 N95 challenge masks. Carbon dioxide was not amongst the investigated parameters. The target of the study conducted by Lim et al. (2006) to be to determine the ubiquity of headaches native the usage of N95 face masks amongst healthcare workers. Around 40% the the participants reported face-mask-associated headaches. The study carried out by Roberge et al. (2010) assessed the physiological influence of N95 filtering face-piece respirators on health care workers. The parameters assessed consisted of the concentration the carbon dioxide and also oxygen in the mask’s dead space. The detected carbon dioxide concentration were around 3% (30000 ppm). Such high concentrations space typically connected with detrimental physiological effects such as headache, anxiety and confusion. In the study, the sampling was done via a sampling heat attached to a port in the mask that was equidistant between the nose and also the mouth and also therefore more than likely measured the contempt diluted carbon dioxide concentration in the exhaled air fairly than in the breath zone. Another study explored the results of confront masks (cloth mask and record face masks) top top CO2, love rate, respiration rate and oxygen saturation top top instructor pilots (Dattel et al., 2020). Also in this study reasonably high carbon dioxide concentration (around 45000 ppm) to be detected. The methodological description however does not enable the unequivocal identification of the precise sampling point, making it difficult to assess whether the measure up concentrations describe the exhaled waiting or come the breath zone.

This examine aimed to identify the concentration the carbon dioxide in the breath zone if wearing a challenge mask. Three species of confront masks were tested under different conditions (office work, sluggish walking and fast walking). The measure concentrations were compared versus existing threshold values for vital levels that carbon dioxide.


 2.1 Tested confront Masks

Three different species of challenge masks were tested:

A medical confront mask (also well-known as a operation mask) conform through the european Union’s health and also safety criter (CE mark): This form of confront mask is generally used by health treatment workers, ensuring a obstacle that boundaries the change of one infective agent between the hospital staff and also the patient. During the COVID-19 pandemic, surgical confront masks have been recommended together a means of source control because that persons who are either symptomatic or asymptomatic to avoid the spread out of respiratory tract droplets produced by sneeze or sneezing. The applications of clinical masks as resource control has actually been presented to decrease the release of respiratory droplets carrying respiratory viruses (Leung et al., 2020) and also they are recommended for the palliation of infection of influenza (Cheng et al., 2010; MacIntyre and Chughtai, 2015; MacIntyre et al., 2015). Medical masks comply with requirements defined in European standard EN 14683:2019 (European Committee because that Standardization, 2019).KN95 v a one-way valve: N95 is an American standard regulated by NIOSH, i m sorry is part of the Centers for an illness Control (CDC). KN95 masks space the equivalent Chinese typical for masks. Both N95 and KN95 correspond to the FFP2 code offered in the europe Union (European Committee because that Standardization, 2001) and also protect against solid and also liquid irritating aerosols with a minimum filter efficiency of 92%. The mask tested in this work consisted of a one-way exhalation valve that provides it much easier to breath through. This kind of mask is no recommended together an reliable barrier against the SARS-CoV-2 virus due to the fact that the valve publication unfiltered air when the wearer breathes out and therefore walk not protect against the wearer from spreading the virus. That was included in the study to evaluate the potential affect of the exhalation valve on the concentration of collected carbon dioxide.Cloth masks: because surgical and FFP2 masks were sometimes an overwhelming to uncover at the start of the pandemic and, especially the FFP2 masks should be scheduled for health care providers, cloth masks have come to be popular throughout the pandemic as they space cheap, basic to find or to make and also can it is in washed and also reused. Towel masks have the right to be do from usual materials, such together sheets made of strict woven cotton, and should include multiple layers of fabric. There space no requirements or regulations because that self-made cloth face masks. The mask supplied in this study was made by a north Italian agency that convert its manufacturing from sportswear to confront masks throughout the pandemic. It to be made of 3 layers: the internal and also external layers were primarily made of polyamide, and also the inner filter was made out of polyester.

 2.2 Instrumentation

Carbon dioxide concentrations to be measured with a TSI 7545 IAQ Meter (TSI Incorporated, Shoreview MN, USA) equipped with a low-drift dual-wavelength NDIR CO2 sensor. This instrument has a declared measurement concentration range of 0–5000 ppm and also an accuracy of ± 3.0% of reading or ± 50 ppm (whichever is greater). Its resolution is 1 ppm. The instrument to be calibrated against a an additional carbon dioxide typical (470 ppm). All dimensions were carry out on the same day the instrument to be calibrated.

 2.3 experimental Setup

The concentration that carbon dioxide in the breath zone was figured out by aspirating air v a silicon pipe from the breathing zone behind the face mask. The sampling point was just above the nose tip on the leg of the nose. In this way, the suggest of sampling was no located directly in the exhaled air stream while at the same time being completely covered through the confront masks. Changing of the silicon pipe was impede by solving the tube to the leg of the nose with some tape. It was then put through a perforated confront shield holder. Indigenous there, the pipe was directed over the head, where it was additional fixed v a lid (Fig. 1).

Fig. 1. Experimental setup. (A) Sampling allude close to the sleep tip; (B) place of the sampling suggest while the confront mask was worn; (C) activity pattern ‘Office work’; (D) activity pattern slow and also medium rate walking ~ above a treadmill.

The aspirated air to be then performed to the CO2 sensor. The sensor-containing probe is usually straight exposed to the surrounding air in i m sorry the carbon dioxide concentration is measured. In this study, a collar that offers a close up door area roughly the gas probe and also that is typically used for calibration objectives was hermetically sealed through some tape come the lower part. A sampling point made of Teflon was combined into the sealing tape. In this way, the air circulation passed undiluted over the CO2-sensor. A pump was associated to the finish of the sampling train (Fig. 1(c)).

The concentration the carbon dioxide to be measured because that two activity patterns: in the very first scenario the male, 50 year old volunteer was functioning on a computer, breathing with the nose and also remaining seated for the term of the measurements. Under these conditions, every three species of challenge masks were tested. In the 2nd scenario, the volunteer was walking top top a treadmill in ~ 0, 3 and also 5 km h–1. While in ~ 0 and 3 kilometres h–1, the volunteer to be breathing with his nose, in ~ 5 km h–1 he to be breathing v his mouth. Each brand-new condition was preceded by the it is registered of a baseline (the same condition but without the masks being worn). The sampling duration for each activity pattern was 5 minutes. The data collection frequency (sampling rate) was collection at 1 s–1.


Fig. 2 shows the concentrations of carbon dioxide measure up for all three types of confront masks while functioning on the computer, staying seated every the time and breathing v the nose. The concentrations were 2107 ± 168 ppm, 2293 ± 169 ppm and 2051 ± 238 ppm because that the surgical, the KN95 and also the towel mask, respectively. No relevant difference in the detected carbon dioxide concentration could be observed among the 3 mask models. Even with the one-way exhalation valve on the KN95 challenge mask, under this conditions, the form of mask had no far-reaching impact top top the carbon dioxide concentration in the breath zone. The baseline concentration, equivalent to those periods of time once no mask was worn, was 501 ± 42 ppm. The concentration of carbon dioxide in the breathing zone while wearing the confront mask did as such increase in median by around 1650 ppm.

Fig. 2. Concentrations the carbon dioxide measured for all three species of face masks while working on the computer, continuing to be seated every one of the time and also breathing with the nose

Since no distinction was observed among the varieties of challenge masks worn, in the 2nd scenario (walking top top a treadmill at different speeds), the measurements were make while wearing only the surgical mask. Fig. 3 depicts just how the baseline concentration of CO2 in this setting, contrasted to the office-activity setting, is slightly greater and exactly how it slowly increases in time (737 ± 27 ppm prior to ‘standing still’ measurements, 744 ± 24 ppm prior to ‘walking in ~ 3 kilometres h–1 measurement and 890 ± 51 ppm prior to ‘walking at 5 kilometres h–1 measurement). This can be defined by the reasonably small room in which the treadmill to be located, which led to an enrichment of carbon dioxide native exhalation in the room. The typical concentration that 2226 ± 165 ppm if standing tho was, as expected, in the same range as the concentrations measured when doing office work. A small increase in concentration (2536 ± 245 ppm) might be observed while walking in ~ a rate of 3 kilometres h–1. This speed coincides to a leisurely walking pace (low activity). A more increase in the detected carbon dioxide concentration to be observed if walking at 5 kilometres h–1 (2875 ± 323 ppm), which synchronizes to a higher walking speed (medium activity) through breathing v the mouth and an augmented breath rate.


Fig. 3. Concentrations of carbon dioxide measure up while wade on a treadmill in ~ 3 and 5 km h–1.

Inhaled carbon dioxide at lower concentrations ( 50000 ppm), it causes the development of hypercapnia and respiratory acidosis (Permentier et al., 2017). A concentration the 5000 ppm is the rectal exposure border (as 8-hour TWA) in many jurisdictions. Exposures to raised inhaled CO2 concentrations between 2–3% (20000–30000 ppm) are recognized to develop sweating, headache and dyspnoea (Schneider and Truesdell, 1922). Inhaled concentrations between 4 and 5% (40000–50000 ppm) are connected with dyspnoea, increased blood pressure, dizziness, and headache (Schneider and Truesdale 1922; Schulte 1964). If inhaled CO2 concentrations are at 5% (50000 ppm), mental depression may take place within several hours (Schulte, 1964).

The concentrations measured in this study room all far listed below these threshold values and range between 2150 ppm (office work) and 2875 ppm (walking in ~ 5 kilometres h–1). Concentration of CO2 in this variety and their association with health symptoms are commonly discussed in the context of the “sick structure syndrome” (Apte et al., 2000; Seppaenen et al., 1999; Wargocki et al., 2000). In a building, the carbon dioxide emissions are about proportional come the climb in odorous substances given off by humans by perspiration. In rooms in i m sorry no combustion processes room taking place, the carbon dioxide concentration can because of this be concerned as an indicator the the at home air quality. Carbon dioxide-related health-symptoms have actually been observed at concentrations above 1000 ppm and include drowsiness and also loss of fist (Guais et al., 2011). A part of the human populace has been explained as being sensitive to fluctuating CO2 concentrations. As a vasodilator, the result on human being prone come headache has additionally been discussed. Because that example, Lim et al. (2006) administered a inspection to medical care workers to recognize risk factors associated with the breakthrough of headaches. Roughly 40% that the respondents reported wearing face masks was connected with headaches. This study did not, however, report the inhaled CO2 concentrations. Satish et al. (2012) suggested in their research that also moderately elevated CO2 concentrations (approximately 2500 ppm) have the potential to influence decision-making.


The concentration of carbon dioxide measure up in the breathing zone if wearing a challenge mask ranged between 2150 and 2875 ppm relying on the kind of activity. The concentration of carbon dioxide there is no wearing a confront mask varied from 500–900 ppm, matching to typical carbon dioxide concentrations in at home environments. Doing office work and standing tho on the treadmill each brought about carbon dioxide concentration of roughly 2200 ppm. A little increase of approximately 300 ppm can be observed as soon as walking at a rate of 3 kilometres h–1 (leisurely go pace). Walking in ~ a rate of 5 km h–1, which coincides to medium activity with breathing with the mouth, caused an typical carbon dioxide concentration that 2875 ppm. No distinctions were observed amongst the three species of tested challenge masks. According to the literature, these concentrations have no toxicological result when inhaled. However, concentrations in between 1,000 ppm and 10,000 ppm can cause undesirable symptoms such as fatigue, headache and also loss of concentration. This may be relevant for those segment of the population required come wear confront masks over an extensive periods of time such as students, bus drivers or cashiers and also persons v respiratory diseases. Wearing challenge masks only as soon as strictly essential may minimize these undesired next effects.

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We say thanks to Ivana Bianchi and also Josefa Barrero-Moreno because that comments that substantially improved the manuscript.