Most inspired particles such as dust fail to reach the lungs because of the .a. ciliated mucous lining of the upper respiratory tractb. abundant blood supply to nasal mucosac. action of the epiglottisd. porous structure of turbinate bones

so many dust particles are there in the air. during inhalation, those particles fail to reach our lungs due to the presence of ciliated mucous lining in our upper respiratory tract.  

primarily nose and its ciliated mucous lining and nasal hair prevent the dust particle to come inside. if some particles get entry then the person starts sneezing until those particles are out.  

if the nose fails to prevent the dust then our respiratory tract does it.