COVID-19 severity and air pollution: what’s the connection?

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  • Researchers investigated the link between long-term exposure to nitrogen dioxide (NO2) and the need for intensive care and mechanical ventilation for COVID-19.
  • They found that exposure to higher levels of NO2 correlates with a higher need for ICU care and mechanical ventilation.
  • The researchers caution that their study only found correlation – not causation – and that further research is needed to better understand their results.

Nitrogen dioxide (NO2) is a traffic-related pollutant gas emitted during the combustion of fossil fuels.

Long-term exposure to NO2 causes many health problems and is linked to higher risk death from all causes, cardiovascular and respiratory.

A study conducted with health care data from 4,443 fatal cases of COVID-19 in 2020 found that long-term exposure to high levels of nitrogen dioxide is correlated with an increased risk of death from COVID-19 .

Knowing how long-term exposure to nitrogen dioxide affects COVID-19 outcomes could help policymakers better allocate resources to treat the disease.

Recently, researchers have studied the effects of long-term exposure to NO2 and the need for intensive care and mechanical ventilation treatment for COVID-19.

They found that long-term exposure to NO2 was linked to an increased need for intensive care and mechanical ventilation.

The researchers presented the results to the Euroanesthesia Congress in Milan, Italy.

The researchers collected air pollution data from 2010 to 2019 for 392 of the 402 German counties for the study. They used this data to calculate long-term annual average levels of NO2, ranging from 4.6 µg/m³ to 32 µg/m³. The lowest levels were in Suhl and the highest in Frankfurt.

They also collected data on the number of occupied intensive care beds and the need for mechanical ventilation from the register of the German Interdisciplinary Association for Intensive Care and Emergency Medicine from April 16, 2020 to May 16, 2020, when the government officials have lifted lockdown restrictions.

Then they analyzed the data and adjusted their results for demographic factors such as population density, age and sex distribution, socioeconomic factors, and health parameters such as pre-existing health conditions affecting severity. of COVID.

In total, they noted that there were 169,840 cases of COVID-19 in Germany through May 16, 2020, and 8,433 COVID-related deaths.

Their analysis of the data found that a 1 μg/m3 increase in NO2 was associated with a need for intensive care of 3.2% and a need for mechanical ventilation of 3.5%.

When asked what might explain the results of the study, Dr. Tia Babuacting assistant professor in the University of Washington’s division of allergies and infectious diseases, not involved in the study, said Medical News Today:

“Nitrogen dioxide exposure is associated with a myriad of effects on the lungs, including lung damage, decreased lung function and inflammation,” Dr. Babu said. “Perhaps chronic exposure to nitrogen dioxide results in decreased lung function or an abnormal local lung immune response to the SARS-CoV-2 virus.”

DTM also spoke with Dr. Fady Youssef, board-certified pulmonologist, internist, and critical care specialist at MemorialCare Long Beach Medical Center in Long Beach, California. Dr. Youssef did not participate in the study.

He said pollutants can promote a pro-inflammatory state in the lungs that can have an additive effect on the inflammation triggered by COVID-19.

Dr. Susanne Kochprofessor in the Department of Anaesthesiology and Intensive Care, Charité – Universitätsmedizin Berlin, Germany, lead author of the study, explained this additive effect to DTM:

“[A protein called] ACE-2 helps “slow down” inflammation, but exposure to airborne pollutants triggers inflammation or “releases the brakes.” And again, when the SARS-CoV-2 virus binds to ACE-2, these brakes are removed, leading to an additive effect, more severe inflammation, and more severe course of COVID-19.

The researchers concluded that individual risk of morbidity from COVID-19 is influenced by long-term exposure to NO2.

Asked about the limitations of the study, Dr. Koch said DTM that due to the cross-sectional epidemiological design of the study, their research does not guarantee causal relationships. She also noted that because many COVID-19 risk factors can be triggered by air pollution, their models may underestimate its impact on health.

Dr Youssef added: “There are many other variables that may be associated with environments with high NO2 levels that could be responsible for the correlation, [although] the study controlled some of them.

Babu noted that examples of these other variables, including differences in medical practices in urban areas such as increased care capacity in intensive care units, may have contributed to the study’s observations.

Liuhua Shi, ScDassistant professor in the Gangarosa Department of Environmental Health at Emory University, further explained that NO2 could also serve as a proxy for unexamined traffic-related air pollutants such as soot, trace metals and ultrafine particles.

Dr Shi added that the study did not assess real-time exposures and country-level characteristics may not represent the characteristics of individual COVID-19 patients, meaning that their adjustment for socio- economic, health and demographic may be inadequate.

Asked what this study means for the environment, Koch explained:

“Although the COVID-19 pandemic may end by achieving herd immunity through infection or vaccination, exposure to ambient air pollution will continue to affect people’s health. The only remedy is to reduce emissions.

“The transition to renewable energy, clean transport and sustainable agriculture is urgently needed to improve air quality, which will also help mitigate climate change, improve people’s health and the quality of life in the world”, she concluded.

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