Which component present in the eyes,skin,or saliva acts as a physiological barrier to resist microorganisms?

Why is it that during changing weather,one is advised to avoid closed,crowded,and air-conditioned places like cinema halls?

$DPT$ vaccine doses are administered at specific intervals after birth. Identify the correct sequence for the $1^{st}$, $2^{nd}$, and $3^{rd}$ doses of $DPT$ from the following list:
$I$. $6 \; \text{weeks}$ after birth
$II$. $10 \; \text{weeks}$ after birth
$III$. $14 \; \text{weeks}$ after birth
$IV$. $24 \; \text{weeks}$ after birth
$V$. $29 \; \text{weeks}$ after birth

Match the following columns correctly.

Column-$I$	Column-$II$
$(P)$ Pertussis	$(i)$ Virus
$(Q)$ Dengue	$(ii)$ Protozoa
$(R)$ Amoebiasis	$(iii)$ Helminth
$(S)$ Filariasis	$(iv)$ Bacteria

$NFCP$ stands for

What precautions are required in case of airborne diseases such as pneumonia and the common cold?