Why do smoke detectors turn a blind eye when encountering smoking ?

I think everyone has their own confusion about smoke detector alarms. "I saw a smoke detector on the ceiling of the hallway, but why didn't it sound an alarm? Can't it detect the smoke produced by smoking?" "Our company has a smoke detector on the ceiling of the office area. When working overtime at night, occasionally a colleague secretly smokes at the workstation, but never sees it sound."

So, can smoke detectors detect the smoke produced by tobacco?
The answer is no, if the smoke emitted by the smoker blows directly at the smoke detector alarm, it will definitely sound an alarm. But nowadays, smoke detectors are usually installed on the roof, and if a person smokes at a distance below them, the probability of the alarm will be very low. The smoke detector is mainly used to monitor fire smoke and is not a detection instrument for tobacco smoke. The sensors inside the smoke detector alarms are not as sensitive, and the concentration of smoke from smoking one or two cigarettes does not meet the alarm standards.

In addition, for some public places where smoke detector alarms are not sensitive to cigarette smoke, smoke detector alarms do not fail to alarm, but have a certain probability, which is also related to smoke concentration.