"令人窒息的浓烟" can be translated into English as "suffocating thick smoke".
"suffocating" conveys the feeling of being unable to breathe easily, matching "令人窒息的" (lìng rén zhì xī de, which means "choking" or "suffocating").
"thick smoke" accurately describes "浓烟" (nóng yān, meaning "dense smoke").
This phrase effectively captures the intensity and danger of the smoke.