I observed six different types of face masks being used in India during the COVID-19 pandemic under my Foldscope. Depending on the size of the spaces between the fibres of the masks, I analysed the ability of each mask to protect the wearer, and those around the wearer.

Blue Disposable Mask

A regular, single-use disposable mask available at most local pharmacies.

The topmost layer of fibres is in focus. There is very little light passing through, indicating that there are less gaps. The gaps and fibres are evenly spaced.

Conclusion: Safe

Green Disposable Mask

Another type of regular, single-use disposable mask available at most local pharmacies.

The mask has a dotted pattern on the surface when seen up close.

Multiple layers of fibres are in focus and visible. There are some large gaps between the fibres. Light passing through is bright, indicating that there are no fibres there. The fibres are not evenly spaced; in some areas they are dense, in others they are sparse.

Conclusion: Not safe

Surgical Mask (procured from a tertiary hospital pharmacy)

This has an appearance similar to that of a regular blue disposable mask.

The topmost layer of fibres is in focus. It looks a lot like the blue mask above, but the light passing through in this case is of uniform brightness throughout.

Conclusion: Safe

Single-layered Cloth Mask

A flimsy, thin cotton cloth mask; the one people opt for out of preference for convenience, comfort, and perhaps fashion.

Clearly, this is not a mask worth wearing. The gaps between the weave of the fibres are immense; and the light shines through, unblocked.

Conclusion: Not safe

Triple-layered Cloth Mask

This mask is thicker than the cloth mask observed previously. It is reusable and washable.

The beautiful weave of the threads in the topmost cloth layer is clearly visible. These cloth fibres look very different from the synthetic ones in the disposable masks. There are few gaps in the top layer itself, not including the finer middle layer. Very little light passes through, and the spaces between the threads are small.

Conclusion: Safe

Multiple-use N95 Mask

A washable N95 mask which can be used many times. It is slightly thicker than disposable masks, but ensures comfort and breathability.

The topmost layer of fibres is in focus. The fibres are spaced evenly and densely. There is absolutely no bright light passing through without incurring an obstruction, indicating almost zero gaps.

Conclusion: Safe

The result (from safest to most unsafe):

1. Multiple-use N95 Mask
2. Surgical Mask
3. Triple-layered Cloth Mask
4. Blue Disposable Mask
5. Green Disposable Mask (with dotted pattern)
6. Single-layered Cloth Mask

Footnote

A newspaper article I came across at a much later date, which further verifies my findings.

https://www.newindianexpress.com/states/karnataka/2021/mar/07/layered-masks-protect-but-can-spread-virus-says-iisc-study-2273385.html

Always remember the three golden rules of wearing a mask too!

1. Do not touch the outside of the mask.
2. Pick a mask that is snug and fits you well, so that you don’t keep touching it to adjust it.
3. Make sure the mask covers your nose and mouth, at all times.

Also, never wear a valved mask. It protects you, but not others near you.

CookerBird