An instrument is required to be correlated with the endogenous variable but not the error term in the outcome equation (for detailed presentation of this method, see any econometric textbook, e.g., [25])
The combustion of tobacco produces harmful chemicals, including nicotine, tar, carbon monoxide, and various carcinogens known to cause serious health issues such as lung cancer, heart disease, and respiratory disorders such as pulmonary fibrosis and COPD
These microbes have been shown to help reduce the amount of nicotine in tobacco leaves, while still maintaining the same taste of tobacco and assuring the leaf can still be smoked properly
In addition, antihistamines are beneficial for those suffering from allergic pharyngitis or postnasal drip
Vomit odors