The need to wear a mask emerged as one of the most controversial and politicised aspects of the pandemic and new research from South Korea has rekindled debate, as the new COVID variant spreads, about the safety of wearing the universally recommended N95.
Fifteen species of the VOCs detected from mask samples were consistent with the hazardous chemicals commonly found in work environments, as identified by the US’ National Institute for Occupational Safety & Health (NIOSH).
Among these 15 hazardous chemicals, DMAc and DMF are known to potentially cause liver and reproductive toxicity, and aromatic compounds such as toluene and xylene are toxic to the nervous system.
Acetonitrile is also a harmful substance that can cause inflammation to the skin and eyes and can cause neurological disorders; n-Hexane is a skin irritant that can cause headaches and pulmonary oedema when inhaled: while simultaneous exposure to n-hexane and 2-butanone can cause severe neurotoxicity.
The study was picked up and run by FOX News earlier this week and already, its impact on the US mask debate has become politicised, with the findings seized on by the anti-vax and anti-mask movements associated with the American right.
According to the team from Jeonbuk National University, an increase in the concentration of environmental particulate matter and the spread of the COVID virus have dramatically increased our time spent wearing masks and if harmful chemicals are released from these masks, there may be harmful effects on human health.
Their study, published in Ecotoxicology and Environmental Safety, assessed the concentration of volatile organic compounds (VOCs) emitted from commonly used face masks under diverse conditions, including different mask material types, time between opening the product and wearing, and mask temperature.
Working standards including a total of 27 VOCs were prepared to evaluate the concentrations of chemicals generated by each type of mask, with a particular focus on the KF94, the Korean Filter with a 94% filtration level, that was widely adopted by medical staff during the first year of the pandemic, when the supply of N95’s was limited.
“It is the South Korean equivalent to the N95 mask, with a few differences,” explained Dr Ravina Kullar, an infectious-disease specialist, epidemiologist, and spokesperson for the Infectious Diseases Society of America.
“It combines elements of an N95 mask with those of a cloth mask, contouring close to the face with an adjustable band around the bridge of the nose.”
The team from Jeonbuk University conducted three experiments to assess the level of hazard posed by VOCs:
- In Experiment 1, the types and concentrations of VOCs generated from the mask samples were compared – the mask samples were taken out of the product packaging and injected into a 1 L capacity impinger.
- In Experiment 2, KF94 masks were employed to evaluate whether the concentration of VOCs emitted from the masks changed depending on the time elapsed after opening the packaging.
- While Experiment 3 assessed whether VOC concentrations increased as mask temperature increased.
In KF94 masks, 1-methoxy-2-propanol (221 ± 356 µg m–3 ), N,N-dimethylacetamide (601 ± 450 µg m–3), nhexane (268 ± 349 µg m–3), and 2-butanone (160 ± 244 µg m–3) were detected at concentrations 22.9 – 147 times higher than those found in masks made from other materials, such as cotton and other functional fabrics.
Additionally, the total VOC (TVOC) released amounted to 3730 ± 1331 µg m–3, about 14 times more than that released by the cotton masks (267.5 ± 51.6 µg m–3), with some KF94 mask TVOC concentrations reaching over 4000 µg m–3, posing a risk to human health – based on indoor air quality guidelines established by the German Environment Agency.
Notably, 30 min after KF94 masks were removed from their packaging, TVOC concentrations decreased by about 80% from their initial levels to 724 ± 5.86 µg m–3; furthermore, 6 h after removal, TVOC concentrations were found to be less than 200 µg m–3.
The study also found that when the temperature of the KF94 masks was raised to 40 C, TVOC concentrations increased by 119–299%.
“When masks are worn close to the face, temperature may increase beyond the ambient temperature due to body heat,” the authors explained.
“Sunlight and ambient temperature also act as a factor in increasing the temperature of the mask. When the temperature of the mask rises, the types and concentrations of the VOCs emitted from the mask can rise with it.”
As the mask temperature increased, VOC concentrations across all functional groups rose. Hydrocarbons, which recorded the highest concentrations were at 25 C (1286± 644 µg m–3), showed the highest concentration among all functional groups, even at 40C (4404 ± 712 µg m–3).
An increase in concentrations of ester (244 ± 157%), amide ) 244 ± 294%), and ketone (229 ± 102%) was also observed, and the mean concentrations of the six functional groups (oxane, oxirane, dioxane, cyanide, aldehyde, and siloxane), which were recorded at relatively low concentrations at 25C (C (23.7 ± 18.6 µg m–3), more than doubled once mask temperature reached 40 (68.4 ± 59.0 µg m–3).
“However, the concentration levels of the VOCs detected were very low, nearly 100–1000 times less than the recommended exposure limit set by NIOSH.
Nevertheless, the guidelines related to safe mask wearing are required as these 15 VOCs are harmful substances.
“The VOCs adsorbed on the surface of the mask are easily volatilized into the air by breathing or wind. Accordingly, the number of VOCs emitted from masks can vary depending on the elapsed time after the mask is opened.
“As we observed, as soon as the mask packaging was opened, the mass flow rate of the VOCs generated from the mask rapidly declined.
“Wearing a mask immediately upon opening the packaging could result in exposure to a TVOC concentration of 3702 ± 1339 µg m–3. However, exposure can be significantly reduced if a mask is opened and left to sit for at least 30 min.”
When KF94 masks were opened and left undisturbed for 30 min at room temperature, TVOC concentrations significantly decreased to 724 ± 5.86 µg m–3 – a 78.2 ± 9.45% reduction from opening levels.
“It is clear that particular attention must be paid to the VOCs associated with the use of KF94 masks their effects on human health,” the authors concluded.
“Based on our findings, we suggest that prior to wearing a KF94 mask, each product should be opened and not worn for at least 30 min, thereby reducing TVOC concentrations to levels that will not impair human health.
“However, since the types and concentrations of VOCs that will be inhaled by mask wearers vary depending on the mask use conditions, it is still necessary to comply with safe mask wearing conditions.”