Q.Define Suspended Particulate Matter (SPM) and Respirable Suspended Particulate Matter (RSPM, also called $\text{PM}_{10}$), stating the particle-size cutoff that distinguishes them.

Airborne solid and liquid particles are classified by size. Suspended Particulate Matter (SPM)

is the broad category of all particles suspended in air, up to about $75~\mu\text{m}$ in diameter;

coarser particles are mostly trapped by the nose and upper airway's natural filtering.

Respirable Suspended Particulate Matter (RSPM), also written $\text{PM}_{10}$, is the finer

fraction below about $10~\mu\text{m}$ -- small enough to bypass that upper-airway filtering and

penetrate deep into the bronchioles and alveoli of the lungs, where it can lodge and cause long-term

harm. Because of where it ends up in the body, RSPM is considered far more dangerous to health than

an equal mass of coarser SPM. Natural sources of particulate matter include windblown dust and …