In this era of Corona panic and fear, there are lot of confusions and misconceptions existing regarding the use of mask, not only amongst the laypersons but also among the health care providers.
On one hand masks are not available for the risk group while on other hand, who are not at risk, spending unnecessary money and energy to procure these masks.
Hope this questionnaire would improve the understanding about the various types of commonly used masks and clarify the proper indications of use.

Q1 ... What are the common types of masks
Ans...
1 Cloth mask
2 Surgical mask

Q2... What are the Respirators
Ans.
N- 95
N- 99
N- 100
are the respirators

Q3.. what is the difference between mask and respirator
Ans..
Mask has  loose fit, it doesn't seal nose and mouth snugly.
During respiration air moves along the edges of the mask, while respirator has tight seal and most of the times air passes only through its material after filtration.

Q4... Are all respirator masks are same
Ans...
No, respirators are graded according to their filtration efficiency.
According to the used filter type
According to the type of materials used
And additional features
They are of different types.

Q5... what is the efficiency grading
Ans...
According to the efficiency of filtration these are usually graded as-
95, 99 and 100
Means these respirator masks are capable of traping 95%, 99% and 99.9% of particles, smaller up to the 0.3 micron size.
This grading can also be done as
P1 (FFP1) - 80%
P2 (FFP2) - 95%
P3 (FFP3) - 99.95%
Filtration efficiency.

Q.6.. what is the N,R or P meaning written over mask
Ans...
N - not oil proof
R- oil resistant
P- oil proof
(Eg. N 95 is not oil proof).

Q7. Few repirator masks have valve, what is that.
Ans..
That valve is nothing but a simple exhalation port with one way valve mechanism, it reduces effort of expiration, reduce heat inside the mask, dissipate humidity and reduce co2 the amount of from the  dead space of mask.

Q.8.. When to use surgical masks.
Ans... Surgical mask or procedure mask is the most common mask used by health workers.
It is not designed to protect wearer from inhaling the air born bacteria and viruses.
It is used to block only large particle droplets, splashes, sprays or splatter.
It also reduce the exposure of wearer's saliva and respiratory secretions to  others. Surgical mask also remind wearer not to touch their mouth/nose which could otherwise transfer virus/bacteria after having touched a contaminated surface.

Q9... what is the filtration capacity of surgical mask
Ans... It can vary between 10-90% according to the manufacturer.

Q..10.. how one can assure about the quality of mask
Ans..
Mask should be certified by the
NIOSH (National institute for occupational safety and health)
Or
NPPTL (National personal protective technology laboratory)

Q.11... Does cloth mask effective?
Ans.
Cloth is a wooven material thus pore size is bigger than surgical mask which is made up of non wooven polypropylene material thus cloth mask is less effective than surgical mask in terms of filtration efficiency.

Q..12 ... Does extra layer improve efficacy of cloth mask
Ans.. No, it's not advisable. Each extra layer adds only 2% of extra protection on the cost of comfort .

Q.13... Can surgical/cloth mask be used routinely
Ans.
Yes these can be used routinely.
Few studies done on normal population concluded that the use of simple mask can decrease the incidence of flu up to 75%.
Few east asian countries following this practice of routine use of mask.

Q.14.. Can mask be reused?
Ans. -Cloth mask can be reused after washing
- Surgical mask should be discarded after single use or after soiled
- Respirator mask should be discarded when resistance of breathing get increased or get solied.
Viruses/bacterias can grow and flourish inside the reused mask.

Q..15.. what are the WHO recommendations for using masks?
Ans...
- For the normal population, any type of mask is not required, maintaining the social distance and hand hygiene are the sufficient.
- Sick person should wear surgical mask
- Any person who is taking care of sick person should also wear the surgical mask.
- N 95 mask should be used by the person who is potential to get expose with the respiratory secretions of the infected patient eg. During the Endotracheal intubation, CPR, Ventilation, Bronchoscopy and Tracheostomy etc.

Summary...
Please don't create panic and use this precious commodity judiciously. Stay safe...