Human factors expert: masks may increase business liability

A worker adjusts his mask


This article is the first of a two-article series. The second article, on the efficacy of face masks, can be found here.

Employees who complain of headaches and dizziness may also be suffering from cognitive impairment.

Sal Fariello is concerned that businesses may be subject to liability lawsuits if patrons or employees are injured in accidents that could be caused by carbon dioxide (CO2) build-up under masks.

Fariello is a retired expert witness who has written engineering reports for lawyers and insurance companies dealing with accident causation, human injury biomechanics, human factors, safety and warnings, and product failures. He lives in Gainesville and told Alachua Chronicle that he is worried about unintended consequences of Alachua County’s facial covering mandate, including accidents caused by cognitive impairment.

Fariello pointed out that people respond differently to intoxicating substances; for example, someone who has built up a tolerance to alcohol can drink much more before showing impairment than someone who does not regularly drink alcohol. Physical size, health status, age, and other medications can cause people to react to the same amounts of alcohol differently. The same applies to medications: dosages are often tied to body weight, particularly for children. Fariello says it would be incorrect to conclude that elevated levels of CO2 are “safe” for all people.

Fariello says there is a lot of evidence that counters the assertion of the Centers for Disease Control and Prevention (CDC) that “carbon dioxide, indeed, will collect between the mask and face but not in dangerous amounts and certainly not enough to cause hypercapnia.” 

The U.S. Navy Diving Manual considers hypercapnia to be an “abnormally high level of carbon dioxide in the blood and body tissues,” without giving a specific value. The manual lists confusion, inability to concentrate, and headache among the symptoms and warns that “hypercapnia may give the diver little or no warning prior to onset of unconsciousness.” It can take up to 15 minutes to recover, even after CO2 levels return to normal.

Numerous articles that discuss the possible hazards of CO2 under masks have been subjected to fact-checkers who declare them to be inaccurate. However, mask proponents and fact-checkers have only looked at worst-case scenarios (i.e., levels required to cause unconsciousness) when dismissing concerns about CO2.

Fariello cites his personal experiences in talking to cashiers at local retailers: “I spoke to cashiers at Publix and Walgreens today, and they both told me the same horror story, that every employee in the store was sick from the masks, suffering from brutal headaches, dizziness, and exhaustion.”

He says a person who experiences a headache or dizziness while wearing a mask is likely suffering from other symptoms of hypercapnia, even if they’re not aware of them. 

A simple overview of hypercapnia is provided by verywellhealth.com. The article warns that it is possible to have high CO2 levels even if your oxygen level is normal and says, “Because these effects are so vague, you might not realize that they are caused by hypercapnia.” According to the National Institutes of Health (NIH), CO2 exposure can cause

  • Suffocation by displacement of air
  • Incapacitation and unconsciousness
  • Headaches
  • Vertigo and double vision
  • Inability to concentrate
  • Tinnitus
  • Seizures

Claire Gillespie at Health.com did a light review of the debate on CO2 toxicity. The article quotes Indiana University Professor Bill Carrol, saying CO2 “has to be a pretty high concentration to be capable of causing harm.” He explains that the atmosphere is 0.04% (400 ppm) CO2, but danger only comes when CO2 is over 10% (100,000 ppm).

Dr. Amesh Adalja from the Johns Hopkins Center for Health Security disagrees. He told Health.com, “Someone wearing an N95 mask for a prolonged period of time may have alterations in their blood chemistry.” The N95 mask is “uncomfortable to wear, and it does restrict your breathing… When I wear one to take care of patients I try to keep it on only for as long as I have to.” 

Gillespie and Adalja are talking about different things: toxicity versus impairment. Consider the difference between alcohol toxicity and impairment. According to the NIH, alcohol toxicity occurs around 0.45% blood alcohol concentration (BAC), but impairment starts as low as 0.05%. Florida law (316.193) sets a legal limit of 0.08% BAC, but a driver may or may not be impaired at that level. Police have suspects perform field sobriety tests to determine “the extent that the person’s normal faculties are impaired,” regardless of the BAC. CO2 can also cause impairment well below the level of toxicity.

A review of low-level inhalation exposure to CO2 concluded, “short-term CO2 exposure beginning at 1,000 ppm affects cognitive performances including decision making and problem resolution.” National indoor air quality guidelines set a 1,000 ppm limit in several countries, including Canada, Germany, Japan, Norway, Singapore, South Korea, and Taiwan. The U.S. limit is set by OSHA at 5,000 ppm over 8 hours (40,000 ppm is “immediately dangerous to life or health” (IDLH)).

The review looked at 1,475 articles published between 1950 and 2018 and screened them down to 99 full-text, peer-reviewed original research papers or reviews of experimental studies. “Findings suggest that there is a direct effect of low-level exposure to CO2 on performance,” which “may profoundly affect job competence and learning ability.” Here are some specifics listed in the review (all ppm measurements are parts-per-million concentrations of CO2):

  • Starting at 467 ppm, a 100 ppm increase is significantly associated with dry throat, tiredness, and dizziness (Lu et al., 2015).
  • Starting at 500 ppm, there are physiological responses in heart rate variability and peripheral blood circulation (MacNaughton et al., 2016; Vehviläinen et al., 2016; Kajtár and Herczeg, 2012).
  • Starting at 674 ppm, a 100 ppm increase “was significantly associated with headache” (Norbäck and Nordström, 2008).
  • Above 800 ppm, subjects reported significant increase in eye irritation and upper respiratory symptoms (Tsai et al., 2012).
  • 945 ppm for 8 hours decreased cognitive scores including basic activity, focused activity, crisis response, and information usage (Allen et al., 2016).
  • Above 1,000 ppm, children have a higher risk of rhinitis (inflammation and irritation of mucous membrane of the nose), leading to a stuffy or runny nose, headache, and sneezing (Simoni et al., 2010), as well as decrease in cognitive performance: decision making and problem solving (Satish et al., 2012).
  • 1,500 ppm decreased performance in children in tasks of addition, number comparison, grammatical reasoning, and reading comprehension, compared to 900 ppm (Petersen et al., 2016).
  • 2,000 ppm for 2 hours impacts the immune system and can cause diffuse inflammatory vascular injury, including leaks in the brain, muscle, and distal colon (Thom et al., 2017a).
  • 2,260 ppm for 4 hours increased fatigue and had a negative effect on performance in information retrieval tasks (Maula et al., 2017).
  • At 2,500 ppm, pilots showed significantly lower performance during advanced maneuvers in a flight simulator (Allen et al., 2018).

The cognitive problems associated with hypercapnia are sufficiently worrisome that newer cars are equipped with internal CO2 monitors to allow fresh air into the cabin if the CO2 levels get too high (these are generally set to keep levels below 2500 ppm).

In addition to the cognitive effects, an elevated CO2 concentration lowers the blood pH, causing hypercapnic acidosis. Dr. Jonathan Marhong says this “suppresses both innate and adaptive immune responses.” Murray & Nadel’s Textbook of Respiratory Medicine says the degradation of the immune system from hypercapnia can begin with just 30 minutes of exposure and can last up to 3 days after CO2 is returned to normal levels (p1536). 

Fact checkers like Reuters try to dismiss claims that increased CO2 concentrations could cause harm by saying, ”most people would wear face coverings on short stints outside their home” and  “You might get a headache but you most likely [would] not suffer the symptoms observed at much higher levels of CO2,” but many employees are now wearing masks for 6-10 hours at a time, and complaints of headaches are common, indicating that the masks are causing some sort of physiological changes.

Masks can also reduce the concentration of oxygen (O2) being taken into the lungs. Stanford engineer John Xu says, “N95 masks are estimated to reduce oxygen intake by anywhere from 5 to 20 percent. That’s significant, even for a healthy person.”

The Occupational Safety and Health Administration (OSHA) has adopted a requirement that “air breathed by employees must have an oxygen content of at least 19.5 percent.” According to this interpretation of that rule, oxygen concentrations below 19.5% are hazardous and can cause “increased breathing rates, accelerated heartbeat, and impaired thinking or coordination.” 

The atmosphere at sea level is just under 21%, so a mask that reduces O2 concentration by about 9% would qualify as hazardous by OSHA standards.

This video demonstrates how quickly oxygen levels fall under a surgical mask. The video has been fact-checked by Facebook as “partially incorrect”: “We concluded this was also false, based on the engineers [sic] explanation that exhaled air, which has the depleted oxygen level, is trapped in pockets in the mask.” The point of the video, however, is that exhaled gases are trapped in the mask and reduce the oxygen level in the air that is breathed back in.

Fariello would like to see studies to measure actual concentrations of CO2 and O2 under various types of masks and also to determine how long it takes for blood concentrations to recover if they are indeed affected by wearing masks.

Fariello is concerned that employees who have been wearing masks for hours or older people who wear them for short periods to shop could suffer lapses in judgment or impairment of motor skills that could lead to falls or to car accidents. He concludes, “If businesses require masks, they should be aware of their potential liability if accidents occur on their premises or shortly after leaving their premises.”

  • This has been my experience. CO2 is dangerous. I put on a mask and within minutes began experiencing diminished brain function. After ten minutes I was looking forward to moving to Springs County, and after twenty minutes I was considering voting for Trump. I took off the mask and within minutes sanity returned.

    • Your diminished brain function is not from wearing a mask. Your diminished brain function is because the stork dropped you on your head too many times before someone actually wanted you. You really should consider moving to San Francisco.
      As per your sanity… you remain a person trapped within your own illusions of a liberal “utopia.”

    • So the masks are a giant conspiracy promoted behind the scenes by Trump to make people stupid so they vote to reelect him? Interesting theory.

      • You are right masks raise CO2 levels and this lowers cognitive ability. That’s why Trump doesn’t like wearing them. He has very little to lose.

  • Nurses and doctors have been wearing these with no problems. If you are concerned the way to test is with a pulse oximeter which will come in handy if you lose lung function as a result of the virus.

  • Charles caught my attention with the allegation that “doctors have been wearing these [masks] with no problems.” Really? Are you quite sure? There have been many reports of repeat surgeries where the second surgeon discovered clamps, sponges, etc., left inside the body of the patient during the first surgery. I doubt this happens due to negligence or incompetence. Perhaps Charles is overlooking the possibility that this sort of error occurs because the surgeon’s brain is addled by excessive CO2 in the blood or low O2 due to wearing a mask.

  • Wear masks but don’t expect it to be easy and free of discomfort.
    Its not the lack of oxygen that causes the headaches it is the increase in CO2 levels. The CO2 concentration in the atmosphere is 0.04% . The CO2 that is present in your exhaled breath is 4%. This is 100 times as much and some of it remains under the mask and is immediately rebreathed. However your body is very clever and quite capable of maintaining your O2 and CO2 levels in the right place despite the fact that you are breathing elevated levels of CO2 so medically you see nothing go wrong.
    However it does put your body under stress and causes headaches and loss of mental abilities for many people. This product has been designed to eliminate this problem and make mask wearing safer and more comfortable. http://www.airinsmartshield.com
    We stress however that wearing a mask is not dangerous just uncomfortable particularly for long periods.
    People with reduced mental capacity however should be careful because it will lower cognitive abilities. Donald Trump’s doctors have noted his diminutive mental capacity and advised him not to wear a mask under any circumstances. This may however be the only time he has taken his medical adviser’s advice.

  • Do you have more studies documenting cognitive impairment from wearing masks? There are long-term studies showing that children with subclinical levels of heavy metals in their blood grow up to have somewhat lower IQ than childreni n control groups. I’m wondering if there’s something similar, comparing places where childten in school or college students wear face masks versus places where they don’t.

  • There are many studies of what happens when people work in rooms that have elivated levels of CO2. Although the workplace guidelines usually place a limit of 0.5% (5,000ppm) on working condition these studies show significant reduction in cognitive abilities at levels above 0.15% particularly when it involves complex thinking like a pilot presented with an immergency in a simulation chamber. There is not much connection with the wearing of masks and loss of cognititive ability directly and I have found nothing on either of these things on learning abilities. There is plenty of work done on CO2 inhalation levels when wearing masks. It is generally agreed that wearing a mask will not normally lower O2 levels or raise CO2 levels but people wearing masks are definatly operating well above the 0.5% workplace levels. Typically it is dismissed as a problem by saying try to limit the time to an hour or so. It is very clear that the time is a critical element.
    It would be a very good subject to research because schools and universities have plenty of groups who would take part with good control . Basically what differences do you see in a classroom when wearing and not wearing.
    Answeres to these qustions are urgently needed. There will be no simple answer and definatly a trade off of risks and rewards.
    If you contact me by email I can send you some papers.

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