According to a study by the AIIMS-Gorakhpur, the risk of non-smokers  getting severe COVID-19 increased dramatically when secondhand smoking (SHS) was present at home and work.

The study examined in-patient data to locate patients aged 18 years or older who were infected with COVID-19 and hospitalized from January 2020 to February 2022 with severe symptoms of the illness. 

More than 7,000 chemicals are found in secondhand smoke, which causes lung cancer, coronary heart disease, chronic lung disease and thus can exacerbate the severity of COVID-19.

After adjusting for all possible confounders, it was seen that individuals who had household exposure had a 3.03-fold greater chance of acquiring severe COVID-19 than those who did not. Further, those exposed to SHS at work had a 2.19 higher risk of having severe COVID-19 than those who werent.

Body mass index, blood sugar, blood pressure levels, immunization history, vaccination status, age, marital status, level of education, and socioeconomic standing were all strongly correlated with the severity of the illness.

The results of this multi-center study show that secondhand smoke (SHS) exposure enhances non-smokers susceptibility to COVID-19 severity. Few studies have examined the effect of secondhand smoke on the severity of COVID cases, although studies indicate smoking increases the risk of infection with COVID-19 and the severity of the illness. 

(Source:  https://indianexpress.com/article/lifestyle/health/study-aiims-gorakhpur-secondhand-smoke-severity-covid-19-8487137/)