The United States, knowing this, has determined itself to spread an epidemic.


According to new research from Washington University’s McKelvey School of Engineering in St. Louis, the United States may be part of the blame for the rapid spread in SARS-COV-2, the virus responsible for the spread of COID-19. Credit: Professor Rajan Chakraborty, Washington University in St. Louis

Pollution and Pandemic: A Dangerous Mixture

Research by Chakravarti Lab suggests that as one goes, so does the other – to a point.

The United States may have established itself for the spread of an epidemic, even without knowing it.

According to new research from Washington University’s McKelvey School of Engineering in St. Louis, pollution may be to blame for its rapid spread in the United States SARS-CoV-2Virus responsible for spreading COVID-19.

The research was published online before print in a journal from the laboratory of Associate Professor Rajan Chakraborty in the Journal of Energy, Environmental and Chemical Engineering. Science of the Total Environment.

When it is discovered how ill someone becomes after contracting COVID-19, medical professionals believe that a person’s health – for example, certain medical conditions – can play an important role. . When it is discovered how fast the virus can spread through the community, it finds that the health of the environment is directly related to the original reproduction ratio r.0, Indicating the expected number of people infected for each sick person.

Fertility ratio R0 COVID-19 is directly associated with long-term PM2.5 risk level. And the presence of secondary inorganic components in P.M.2.5 Only according to Chakravarti, makes things worse.

“We investigated more than 40 confusing factors,” said Chakraborty. Of all those factors, “there was a strong, linear association between long-term P.M.2.5 Exposure and R0. “

PM2.5 Refers to ambient particles with a diameter of 2.5 micrometers or less; At that size, they can enter a person’s lungs and cause damage. This is why PM2.5 May be harmful to respiratory health. But how this relates to the spread of COVID-19 through a population has yet to be ascertained.

Chakraborty and his graduate student Payton Beeler, both aerosol researchers who have modeled previous coronoviruses, were interested in the relationship after the two were published in succession. First, a July paper in the journal Science The level of sensitivity for COVID-19 was found to be a driving factor for the epidemic; This is more important than temperature, which researchers initially thought could play an external role.

Then in August, the research published in Journal of infection It was found that the most cases of COVID-19 with critical illness were in places with high pollution levels.

“I was wondering, why, in most states of America, have we had such a rapid spread of the virus?” Chakraborty said. Especially in the first stages of the epidemic. “We wanted to limit our study to the time when the shutdown was happening. For the most part, people remained limited from early March to late April. “

The team decided to visit places where R.0 There was more than one – this is the point at which a person can spread the disease to more than one person, and the disease goes away. At those locations, they looked at 43 different factors – including population density, age distribution, even delays in states’ order of stay home.

Then, using pollution estimates in the US between 2012 and 2017, published by Randall Martin, professor in the Department of Energy and Environment and Chemical Engineering, the team looked for any relationship.

Modeling increased by about 0.25 R0 10% increase in sulfate, nitrogen dioxide and ammonium or SNA composition and an increase of 1 μg / m3 In PM2.5 Mass concentrations, respectively.

They found these linear correlations to be strongest in locations where pollution levels were significantly below national ambient air quality standards (NAAQS), the level of air pollutants considered safe for humans.

“Annual means P.M.2.5 National standards are set at or below 12 micrograms per cubic meter, below you are considered safe. “What we saw, the correlation we are seeing, is far below that standard.” In fact, he saw a rapid increase in R0 When P.M.2.5 Exposure levels were less than 6 micrograms per cubic meter.

Chakravarthy envisages this initial increase in R0, Which is followed by a plateau, once struck 6 micrograms per cubic meter in levels, is the result of initial changes in position; When the air is free from p.m.2.5, A person is unaffected. The initial risk is a catalyst for changes in lung health, resulting in a change in sensitivity from non-sensitization, which is reflected in increased R0.

And although there was no direct connection between black carbon – aka soot – and R.0, Researchers found a connection.

“Our colleagues at St. Louis University suggested a mediation / moderation statistical approach,” a detailed analysis that looks at how additional variables affect the outcome of initial relationships. In this case, the researchers observed the effect of soot on R0, Given the effect of SNA.

“We found that black carbon acts as a kind of catalyst. When soot is present, P.M.2.5 Has an acute effect on lung health, and therefore on R0. “

The mediation / moderation study was not over-useful – one of the common methods of exposure to SNA is through pollution emanating from cars and coal-fired power plants. Both of which also emit soot.

“However, decades of stricter air quality regulations in the US have led to a drastic reduction in nitrogen dioxide levels,” the authors write in the paper’s conclusion, “recent repercussions of environmental regulations that gaseous emissions from power plants and vehicles But weakening the boundary weakens the future air quality scenario. “

“Instead of working to resolve the issue, these vicissitudes may set us up for another epidemic,” Chakraborty said.

Reference: “Ambient Prime Minister2.5 Rajan K. Chakravarthy, Peyton Beeler, Pai Liu, Spondita Goswami, Richard D. Harvey, Shamash Parvez, Aryvan Donkeller and Randall Vee. The risk and rapid spread of COVID-19 in the United States, November 9, 2020, by Martin. Science of the Total Environment.
DOI: 10.1016 / j.scitotenv.2020.143391

The authors have made their data and source code available to the public.

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