Nitrogen dioxide pollution increases vulnerability to COVID-19 through altered immune function

Abstract

Previous ecological studies suggest the existence of possible interplays between the exposure to air pollutants and SARS-CoV-2 infection. Confirmations at individual level, however, are lacking. To explore the relationships between previous exposure to particulate matter < 10 μm (PM 10 ) and nitrogen dioxide (NO 2 ), the clinical outcome following hospital admittance, and lymphocyte subsets in COVID-19 patients with pneumonia. In 147 geocoded patients, we assessed the individual exposure to PM 10 and NO 2 in the 2 weeks before hospital admittance. We divided subjects according to the clinical outcome (i.e., discharge at home vs in-hospital death), and explored the lymphocyte-related immune function as an index possibly affecting individual vulnerability to the infection. As compared with discharged subjects, patients who underwent in-hospital death presented neutrophilia, lymphopenia, lower number of T CD45, CD3, CD4, CD16/56 + CD3 + , and B CD19 + cells, and higher previous exposure to NO 2 , but not PM 10 . Age and previous NO 2 exposure were independent predictors for mortality. NO 2 concentrations were also negatively related with the number of CD45, CD3, and CD4 cells. Previous NO 2 exposure is a co-factor independently affecting the mortality risk in infected individuals, through negative immune effects. Lymphopenia and altered lymphocyte subsets might precede viral infection due to nonmodifiable (i.e., age) and external (i.e., air pollution) factors. Thus, decreasing the burden of air pollutants should be a valuable primary prevention measure to reduce individual susceptibility to SARS-CoV-2 infection and mortality.

Environmental health, COVID-19, and the syndemic: internal medicine facing the challenge

“…Age per se, however, cannot be considered as a synonym of individual frailty and increased vulnerability to COVID-19. Short-term exposure to air pollution, for example, affects the immune function in subjects entering hospital for COVID-19 pneumonia, and increases the in-hospital mortality independently from age [ 6 ]. Furthermore, reduced COVID-19 in-hospital mortality appears to be linked with early production of antibodies against SARS-CoV-2, and this evidence is also independent from age [ 13 ].…”

“…Besides mortality, environmental pollution has also a major role in promoting disabilities [ 39 ] and affects the onset and progression of other leading causes of mortality, as cardio-metabolic diseases [ 50 , 51 ]. Of note, air pollution affects individual vulnerability to infectious diseases, including COVID-19 [ 6 ].…”

“…Instead, we need a wider view towards global public health aspects which takes advantage of the “one-health” approach, a comprehensive strategy that facilitates interdisciplinary, multidisciplinary, and transdisciplinary collaboration between the human health, animal health, and environment sectors. In particular, available evidence clearly indicates how environmental factors such as climate change [ 3 – 5 ], air pollution [ 6 , 7 ], low income [ 8 ] and socio-economic disparities [ 9 ] can worsen the outcomes of COVID-19 in vulnerable communities. This interaction cannot be neglected.…”

Usefulness of vaccine boosters for Covid-19 in Italy and in UK and comparison between in intensive care admissions and deaths of vaccinated and unvaccinated patients. Surprises and implications

“…Unfortunately, the data in Tables 5 and 6 show a clear trend towards an attenuation of the VE even for deaths, and the data should call into question the strategy of repeated, continuous vaccine boosters. Other strategies as well should be debated and studied in depht and implemented, from allowing natural infections (as Icelandic Public Healthcare is proposing, 27 in the setting of a mild dominant variant such as Omicron), to implementation of safer environments, [28][29][30] healthy lifestyles, [31][32][33][34][35][36] and reasonably effective, safe and sustainable early care. [37][38][39][40][41]…”

A correlational analysis of COVID-19 incidence and mortality and urban determinants of vitamin D status across the London boroughs

“…The hypothesis of a COVID-19 air pollution link has been supported by a fast-growing body of literature reporting evidence of positive association between outdoor air pollution and COVID-19 morbidity and mortality in different parts of the world 18 . It is reasonable to suggest that since chronic air pollution has a negative impact on the cardiovascular and respiratory systems, and immune function, it increases the risk of mortality, exacerbates COVID-19 infection symptoms and worsens COVID-19 patients' prognosis 19 – 21 . Given that the majority of air contaminants in the UK, particularly in London, remain far higher than WHO recommendations and the majority of air pollutants are expected to exceed the limits set by European Union and UK directive beyond 2030 22 , 23 , investigating the link between air pollution exposure and COVID-19 mortality and infectivity at borough level in London, in addition to other modifiable factors, should be a priority.…”