choke by smoke, irritates nose
嗆 centers on the physical sensation of choking or irritation caused by smoke or fumes entering the nose and throat.
嗆 combines 口 (mouth) with 倉, which likely contributes the sound. The character expresses choking or irritation from smoke entering the mouth and nose.
The mouth radical 口 beside 倉 suggests smoke or fumes entering the mouth and causing choking. Picture a person coughing as smoke fills their mouth.
For ショウ, imagine a show where thick stage smoke makes the performers choke: show -> ショウ, and the smoke irritates their throats.