窒息 (zhì xī) means 'to suffocate' — it is used for literal physical suffocation (from smoke, water, lack of air) and figuratively for a stifling, oppressive situation (pressure, pollution). It is more severe and physical than 憋 (biē), which means 'to hold back' (breath, emotions, urine) and can be voluntary. 呛 (qiàng) is specifically choking from inhaling the wrong way (smoke, liquid) — a sudden, momentary event, not prolonged suffocation.