Cyanosis is:

Smoking increases . . . . . . content in blood and reduces the concentration of haem-bound oxygen. Fill in the blank suitably.

Carbon monoxide $(CO)$ is harmful to humans because:

In $emphysema$,what happens to the lungs?

'Asthma' is caused by

When a patient's blood analysis shows high levels of carboxyhemoglobin,which of the following conclusions is most likely correct? The patient must have been inhaling polluted air containing an unusually high concentration of ..........