Physical obstruction of nasal passages is only one factor in nasal and sinus congestion, but study tells that temperature and humidity of air are also causative factors –

Team@CMHF

Researchers say complaints of a “stuffy” nose may have as much to do with air temperature and humidity as with actual congestion of nasal passages.
According to the study combinations of air temperature and humidity that produced mucosal cooling were most likely to lead healthy volunteers to report clear nasal passages, whereas actual nasal patency was unrelated to reported sensations of nasal stuffiness.

A perception of a lack of nasal patency is the primary symptom that drives [some] patients to seek medical treatment. A more important determinant appears to be the nature of stimuli delivered to nasal trigeminal nerves.
Perceived coolness in the nasal passages, irrespective of how it is induced, appears to drive the perception of nasal patency, but the role of humidity has not been well examined, they noted.

There was a significant correlation between air temperature and perceived patency.
By establishing that feelings of nasal congestion can be sensory-related, we open doors for more targeted treatment. For example, effective treatments may need to include a focus on restoring optimal humidity and temperature in the patient’s nasal airflow.

Reference: http://www.medpagetoday.com/PrimaryCare/PreventiveCare/29077?utm_content=&utm_medium=email&utm_campaign=DailyHeadlines&utm_source=WC&eun=g333280d0r&userid=333280&email=drchasrani@cmhs.in