NIH Researcher Says Most Viruses are in Small Aerosols

Chinese People Were Already Wearing N95 Face Masks Because of Air Pollution

2018 UK Study of Chinese Masks Shows a Wide Efficiency Range

Has COVID Been Reduced in China Due to More Efficient HVAC Filters?

Air Purifiers with HEPA Filters in Twelve Percent of Beijing Homes

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NIH Researcher Says Most Viruses are in Small Aerosols

In a Lancet paper published on July 24 Dr Kevin P Fennelly, Pulmonary Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health,    concluded that studies of cough aerosols and of exhaled breath from patients with various respiratory infections have shown striking similarities in aerosol size distributions, with a predominance of pathogens in small particles (<5 μm). These are immediately respirable, suggesting the need for personal respiratory protection (respirators) for individuals in close proximity to patients with potentially virulent pathogens. There is no evidence that some pathogens are carried only in large droplets.

These data show that infectious aerosols from humans exist in a wide range of particle sizes that are strikingly consistent across studies, methods, and pathogens. There is no evidence to support the concept that most respiratory infections are associated with primarily large droplet transmission. In fact, small particle aerosols are the rule, rather than the exception, contrary to current guidelines.

These small particles occur without a need for a prolonged time to allow for desiccation, and they are of a size that is immediately respirable. These data also add evidence that could update the current dichotomous infection control guidelines, as was proposed nine years ago.

The logic that transmission within close proximity defines respiratory droplet spread is fallacious, as small particle aerosols are in the highest concentration close to patients and dissipate with distance. There is epidemiological evidence of an increased risk of tuberculosis transmission within close proximity.

Individuals sharing a bed with a source patient with tuberculosis are more likely to be infected than people sharing the same room; in turn, people sharing the same room as the source case have a higher risk than individuals in a different room.

An outbreak associated with an aerosol-generating device used to clean a tuberculous abscess revealed a gradient of tuberculin reactivity, with higher rates among patients in rooms closest to the source case's room.

Physical distancing decreases transmission potential from pathogens in small particles as well as in large particles, although small particles have a greater capacity to travel further.

The variability of transmission among respiratory pathogens appears to be less dependent on the physical particle size emitted by the diseased person, as current guidelines suggest, but more by biological factors such as the size of the emitted inoculum, the ability of the pathogen to survive desiccation and other stresses of aerosolization and airborne transport, and environmental factors such as air movement, temperature and humidity, and host defenses.

Modelling studies and simulated workplace protection studies  in the USA have shown benefits of various types of respirators and little to no protection from surgical masks. A study in the UK found that surgical masks could reduce inert aerosol exposure by two times, but filtering facepiece respirators reduced the exposure by a factor of 100 or higher.

 

Proportions of Influenza Aerosol Particles Sizes in Cough and Exhaled Breath

 

 

This Viewpoint suggests that infection control guidelines should be re-evaluated to account for the predominance of small particles within infectious aerosols. Protective devices available to health-care workers have a range of protection, increasing from surgical masks to filtering facepiece respirators to powered air-purifying respirators. Although these are indicated for close encounters, their limitations highlight the need for improved administrative controls, such as more rapid diagnosis and isolation, and the development of vaccines and treatments. These data support calls for the recognition of aerosol (i.e., traditional airborne) transmission of SARS-CoV-2.

This could facilitate the use of enhanced dilution and directional ventilation and other environmental control options—e.g., air disinfection with ultraviolet germicidal irradiation,

which might be especially helpful in congregate settings such as nursing homes. Implementation of improved infection control measures could prevent future morbidity and mortality among health-care workers. 

https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(20)30323-4/fulltext   

Chinese People Were Already Wearing N95 Face Masks Because of Air Pollution

Why has China recorded only 4634 deaths from COVID whereas the U.S. total is 151,000 or 32.5 times greater. This extreme contrast is the result of a number of factors but one of them is selective use of N95 masks by the public.

At the time of the Wuhan COVID outbreak Chinese people were already using N95 efficiency masks to mitigate the high levels of air pollution encountered in Chinese cities. A detailed analysis in 2015 compared sales of lower efficiency masks and high efficiency masks.  Purchases of the high efficiency masks were tied to rises in the air pollution levels.

If in fact there is a big difference in infection rate between wearing an inefficient and efficient mask it would be comparable to the difference in air pollution protection.  Air pollutants are small in size. The fact that  N95 mask sales increased when pollution levels increased and that 3M was the largest supplier are significant. The hypothesis is that citizens recognize the protection given by higher efficiency masks and may have worn them in a manner which contained the infection primarily to Wuhan.

Air pollution is the fourth leading health risk factor for Chinese people (Yang et al., 2013). Air pollution is associated with elevated rates of mortality, which causes between 350,000 and 500,000 premature deaths each year in China (Chen et al., 2013b). The main driver of air pollution is particulate matter. A recent quasi-experimental study suggests that total suspended particulates (TSPs) reduce life expectancies of residents in North China by over five years (Chen et al., 2013a). To reduce air pollution exposure, the use of facemasks, especially those against PM_2.5, has gained popularity since a series of “airpocalypse” events in 2011. Furthermore, the information disclosure of fine particulates since 2013 has incentivized urban residents to purchase anti-PM_2.5 facemasks. These particulate-filtering masks are more specialized and thus more expensive than those traditionally used by Chinese people for warmth in winter.

A statistically significant relationship between daily air quality and anti-PM facemask purchases was found. Individuals respond to the pollution information with lags up to four days; this lag is likely caused by dynamic avoidance behavior or due to the lags in the online transaction recording system. The preferred model shows that a 100-point increase in Air Quality Index (AQI) boosts total purchases of anti-PM_2.5 facemasks by 70.6 percent and total purchases of all facemasks by 50.4 percent.

Particulate-filtering facepiece respirators remove particles out of the air to protect the respiratory system. The regulation on the certification of the particulate filtering respirators was first promulgated by the NIOSH (1995). China established its own standards by the Standardization Administration in 2009. Anti-PM facemasks are categorized by both the filtration efficiency and the types of particulate matter they can filter. According to standards in different countries, filtration efficiency ranges from over 80 percent to 100 percent. Individuals can choose the type of facemasks based on the source and level of pollution. For instance, the N95 respirator, which is the best-selling model in China, is designed to filter at least 95 percent of airborne particles but is not resistant to oil.

The major manufacturer of anti-PM facemasks relies on e-commerce as their main retail channel. The 3M Company has the largest market share for anti-PM_2.5 facemasks. The 3M Company does not have stand-alone B&M retail stores in China. Instead, it has two official flagship stores with thousands of third-party distributors on Tmall.com and JD.com.

The facemask data set covers the period from January 2013 to April 2014 for 316 cities on a daily basis. Only several prefectures in Tibet and some cities with small populations have no data. We also collected original anti-PM_2.5 facemask transaction records from 176 online stores on Taobao.com and Tmall.com. These online stores are required to disclose transaction records of the most recent month on their own home pages. Due to resource constraints, we only examine the sales data from late September 2013 to October 2013. Although 4400 online stores sold anti-PM_2.5 facemasks during that month, our sample accounted for 70 percent of the total completed transactions. We aggregate the actual sales data from the store level to the national level.

Our preferred model estimates that a 100-point increase in the AQI leads to a 70.6 percent increase in expenditures on anti-PM_2.5 masks and a 54.4 percent increase for all types of masks. We aggregate the city-specific pollution costs to the national level. It shows that the cost of one-day of air pollution in China, with the AQI increasing from 105 to 205, is 80,247 USD, of which, 38,356 USD comes from anti-PM_2.5 masks. These estimates are very low because AQIs are still below the heavily polluted levels. Our previous results show that individuals purchase masks mainly during serious pollution days.

https://www.sciencedirect.com/science/article/pii/S0095069617304771#:~:text=Anti%2DPM%20facemasks%20are%20categorized,80%20percent%20to%20100%20percent.

2018 UK Study of Chinese Masks Shows a Wide Efficiency Range

Investigations of masks being purchased by Chinese in 2018 were undertaken by researchers at  IOM in Edinburgh.  We are contacting them to obtain their current views of their research and insights for COVID mitigation. Here is what they found two years ago

Although a mask may filter tiny particles as advertised, face size and shape as well as movement can lead to leakage as high as 68 percent, researchers report in Occupational & Environmental Medicine.

“Even if the filtration efficiency of the mask is high, and the mask fits the person initially, the mask may not continue to give a good fit as the person goes about their daily activities - walking, talking, and more,” said senior study author Miranda Loh, an exposure and environmental scientist at the Institute of Occupational Medicine in Edinburgh, Scotland.

“It is important for people to understand that not all masks are effective at reducing exposure to particles in air pollution,” Loh said in an email. “And none of these masks reduced the concentration of pollution gases such as nitrogen dioxide.”

Although masks sold for workplace use generally must meet rigorous standards, there are few controls on masks marketed to consumers and little information on which mask will offer the best protection, the study team writes.

Their assessment of a sampling of masks in Beijing is part of a larger project funded by the Research Councils UK, examining air pollution in the Chinese capital and its health effects.

Air pollution causes an estimated 1.6 million premature deaths in China each year, the study team notes.

At consumer outlets in Beijing, Loh and colleagues purchased nine different mask types that claimed to protect against fine particle pollution known as PM2.5, which includes soot, droplets and other particles smaller than 2.5 microns in diameter.

These tiny particles are components of vehicle exhaust and industrial emissions and can penetrate deep into the lungs, and from there, enter the bloodstream.

Researchers first tested each mask’s filtration efficiency by drawing airborne diesel exhaust through a section of the material for 30 minutes and measuring the particulate matter and black carbon concentrations on both sides. They also tested four masks on 10 volunteers who were exposed to diesel exhaust in a lab while performing tasks such as talking, sitting, standing, bending over and walking in place.

In the filtration tests, the average particle and carbon penetration ranged from 0.26 percent to 29 percent, depending on the mask material. In the volunteers, the average leakage around mask edges ranged from 3 percent to 68 percent during sedentary tasks and 7 percent to 66 percent in active tasks. Only one mask had an average leakage below 10 percent in both active and sedentary tests.

“If it’s important for you to protect yourself or your family with masks, choose the best one you can and look for one marketed to workplaces,” said lead author John Cherrie, of the Institute of Occupational Medicine.

“Don’t choose the cheapest option,” Cherrie said in a telephone interview. “Choose the one that’s most likely to do the best job.”

The researchers are now exploring whether people tend to wear face masks only on high pollution days. They also want to know if the proportion of particles removed by the mask is enough to provide health benefits, and how long people must wear a mask to see those benefits.

https://www.reuters.com/article/us-health-airpollution-masks/face-masks-available-to-consumers-may-be-ineffective-against-air-pollution-idUSKBN1I426I

Has COVID Been Reduced in China Due to More Efficient HVAC Filters?

To what extent has the effort to remove indoor air pollutants also resulted in reduced COVID transmission in China.  McIlvaine will be following up with researchers such as those who did this 2018 study.

Whereas the annual average concentration limit is 15 μg·m⁻³, and the 24-h concentration limit is 35 μg·m⁻³. the annual average PM_2.5 concentration among 210 cities in China was in the range of 11–128 μg·m⁻³. It is noted that only 1.4% of the cities were able to meet the first level standard in China. From the histogram distribution of PM_2.5 concentrations shown below it can be concluded that the problem of PM_2.5 pollution in China is very serious

 

Indoor pollution is a combination of both outdoor and indoor sources

 

Indoor levels vary from city to city and  location to location

Current status of indoor PM_2.5 pollution.

The table below lists some of the popular AC products from different air conditioner companies with PM_2.5 purification function, which come from Midea, Haier, Panasonic, Gree and KELON. For example, the air conditioner (AC) products of Midea utilize a washable PM_2.5 purification module with an electronic generator to create an electric field in the dust collection device to captured charged particles, which effectively removes PM_2.5. The air conditioning products of Haier use visualization function to capture PM_2.5. Each AC unit is equipped with a 5-color indicator. When indoor PM_2.5 level exceeds the high limit, the indicator turns red and urge the occupants to turn on the PM_2.5 removal function, and it becomes blue when the indoor PM_2.5 level is back to normal. Panasonic air conditioners release negatively charged “nanoe-G” to be absorbed by PM_2.5 in the air, through which PM_2.5 is negatively charged and collected by electric field with high efficiency. The air conditioning products of Kelon use “three processes” (stripping technology, packaging technology and melting technology) for PM_2.5 purification. The air-conditioners listed are residential models, effective in room size of 10–50 m² (2650–7200 W).

Air conditioners with efficient PM_2.5 purification function.

Go to:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5876983/

Air Purifiers with HEPA Filters in Twelve Percent of Beijing Homes

A 2018 study  analyzed the willingness of Chinese to pay for higher purity air.  Air purifier purchases were used as the vehicle to quantify the willingness. A significant variable was household income.  A significant percentage of the population is using HEPA room air purifiers and this has  to have been a benefit in the COVID battle

It is significant that twelve percent of  Beijing residents have room air purifiers with HEPA filters.

http://home.uchicago.edu/ito/pdf/Ito_Zhang.pdf