The lightheaded feeling created by smoke is caused by carbon monoxide. Carbon Monoxide combines with the haemoglobin in the blood at a greater rate than oxygen, and so does not allow the required amounts of oxygen to be passed throughout the body. If the brain cannot get the correct levels of oxygen from the blood, it cannot function at its full capacity, creating the light headed experience felt when smoke is inhaled. So, in reality, this light headed feeling is a symptom of a toxic exposure.
As tea is highly susceptible to the environment in which it lives, it can contain amounts of pollutants such as fluoride and aluminium.
The fumes which come from the tea when it is smoked are usually of a pleasant aroma. These fumes can be used to smoke meat and fish, giving it a tasty flavour.
In conclusion, inhaling the fumes given off by tea will not create a high, and though they may cause a feeling of relaxation or light headedness, this is due to the inhalation of carbon monoxide, rather than any effect of the tea. A healthier way of getting this feeling of relaxation would be to steep the tea in hot water and drink up. Herbal teas, especially camomile tea, are excellent for creating a calming sensation - one which is completely legal, and completely healthy.