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Zooming In: Visualizing the Relative Size of Particles

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Zooming In: Visualizing the Relative Size of Particles

View the full-size version of this infographic.

Lately, the world’s biggest threats have been microscopic in size.

From the global COVID-19 pandemic to wildfires ripping through the U.S. West Coast, it seems as though our lungs can’t catch a break, or more aptly, a breath.

But just how small are the particles we’re currently battling? And how does their size compare to other tiny molecules?

Specks Too Small to See

While the coronavirus that causes COVID-19 is relatively small in size, it isn’t the smallest virus particle out there.

Both the Zika virus and the T4 Bacteriophage—responsible for E. coli—are just a fraction of the size, although they have not nearly claimed as many lives as COVID-19 to date.

Coronavirus particles are smaller than both red or white blood cells, however, a single blood cell is still virtually invisible to the naked eye. For scale, we’ve also added in a single human hair as a benchmark on the upper end of the size range.

ParticlesAverage Size (microns, μm)
Zika virus45nm
T4 Bacteriophage225nm
Coronavirus
COVID-19 (SARS-CoV-2)
0.1-0.5μm
Bacterium1-3μm
Light dust particle1μm
Dust particle: PM2.5≤2.5μm
Respiratory droplets containing COVID-195-10μm
Red blood cell7-8μm
Dust particle: PM10≤10μm
Pollen grain
15μm
White blood cell25μm
Visibility threshold
(Limit of what the naked eye can see)
10-40μm
Grain of salt60μm
Fine beach sand90μm
Human hair50-180μm

On the other end of the spectrum, pollen, salt, and sand are significantly larger than viruses or bacteria. Because of their higher relative sizes, our body is usually able to block them out—a particle needs to be smaller than 10 microns before it can be inhaled into your respiratory tract.

Because of this, pollen or sand typically get trapped in the nose and throat before they enter our lungs. The smaller particles particles, however, are able to slip through more easily.

Smoky Skies: Air Pollution and Wildfires

While the virus causing COVID-19 is certainly the most topical particle right now, it’s not the only speck that poses a health risk. Air pollution is one of the leading causes of death worldwide—it’s actually deadlier than smoking, malaria, or AIDS.

One major source of air pollution is particulate matter, which can contain dust, dirt, soot, and smoke particles. Averaging around 2.5 microns, these particles can often enter human lungs.

At just a fraction of the size between 0.4-0.7 microns, wildfire smoke poses even more of a health hazard. Research has also linked wildfire exposures to not just respiratory issues, but also cardiovascular and neurological issues.

Here’s an animated map by Flowing Data, showing how things heated up in peak wildfire season between August-September 2020:

What’s the main takeaway from all this?

There are many different kinds of specks that are smaller than the eye can see, and it’s worth knowing how they can impact human health.

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Maps

Visualized: Which Coastal Cities are Sinking the Fastest?

Many major coastal cities are experiencing local land subsidence where underground soil and rock collapse, causing the surface above to sink.

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A cropped map and ranking of the fastest sinking coastal cities in the world by local land subsidence.

Which Coastal Cities Are Sinking the Fastest?

This was originally posted on our Voronoi app. Download the app for free on iOS or Android and discover incredible data-driven charts from a variety of trusted sources.

With sea levels rising, there is cause for concern about the livability of major coastal cities—often huge centers of trade and commerce, and homes to millions of people.

But an overlooked area is how coastal cities are themselves sinking—a phenomenon called relative local land subsidence (RLLS)—which occurs when underground materials, such as soil, rock, or even man-made structures, compact or collapse, causing the surface above to sink.

This can exacerbate the effects of rising sea levels (currently averaged at 3.7 mm/year), and is a useful metric to track for coastal communities.

Creator Planet Anomaly, looks at the top 10 cities ranked by the peak subsidence velocity. This graphic is based on a paper published by Nature Sustainability, which used satellite data to track land subsidence changes in 48 high-population coastal cities located within 50 kilometers of the coastline. Their data collection spanned six years from 2014 to 2020.

ℹ️ Interferometric synthetic aperture radar (InSAR) utilizes two images taken at different times, which are then compared to create an interferogram. This interferogram illustrates changes in land motion relative to a reference point in the satellite’s line-of-sight over time. By analyzing a series of these interferograms, researchers can estimate the long-term velocity of the ground’s surface for each city.

In that time period, they found that 44 of the cities they studied—many of them massively populated, developed megacities, built on flat, low-lying river deltas—had areas sinking faster than sea levels were rising.

The 10 Fastest Sinking Coastal Cities

One of the top cities on the list is Tianjin, China with a population of more than 14 million people, which has areas of the city experiencing peak RLLS velocities of 43 mm a year between 2014–2020. The median velocity is much lower, at 6 mm/year, which means some areas are sinking much faster than the overall metropolitan area.

Tianjin is bordered by Beijing municipality to the northwest and the Bohai Gulf to the east. In June 2023, large cracks appeared on Tianjin’s streets, caused by underground land collapses, a byproduct of extensive geothermal drilling, according to the local government.

RankCityCountryPeak Velocity
(mm/year)
Median Velocity
(mm/year)
1Tianjin🇨🇳 China436
2Ho Chi Minh City🇻🇳 Vietnam4316
3Chittagong🇧🇩 Bangladesh3712
4Yangon🇲🇲 Myanmar314
5Jakarta🇮🇩 Indonesia265
6Ahmedabad🇮🇳 India235
7Istanbul🇹🇷 Turkey196
8Houston🇺🇸 U.S.173
9Lagos🇳🇬 Nigeria172
10Manila🇵🇭 Philippines172

Ho Chi Minh City (population 9 million) in Vietnam also faces similar RLLS rates as Tianjin though its median velocity is much higher at 16 mm/year.

Chittagong, Bangladesh, Yangon, Myanmar, and Jakarta, Indonesia, round out the top five fastest sinking coastal cities by relative land subsidence. They all face a similar web of contributing factors as the authors of the paper note below:

“Many of these fast-subsiding coastal cities are rapidly expanding megacities, where anthropogenic factors, such as high demands for groundwater extraction and loading from densely constructed building structures, contribute to local land subsidence.” — Tay, C., Lindsey, E.O., Chin, S.T. et al.

In fact, Indonesia has ambitious plans to relocate its sinking capital, Jakarta, to another island, a move that could cost the Indonesian government more than $120 billion. This comes after the forecast that one-third of Jakarta could be submerged as early as 2050. Aside from the regular flooding, Jakarta is also extremely prone to earthquakes.

Why Measure Local Land Subsidence?

The researchers of this report argue that local land subsidence is largely underestimated in relative sea level rise assessments and is crucial for the sustainable development of coastal areas.

The data they’ve collected—peak velocity versus median velocity—also allows them to identify specific areas and neighborhoods in cities that are undergoing rapid subsidence and thus facing a greater exposure to coastal hazards.

In New York, for example, their results suggested that subsidence is only localized west of Breezy Point and “should not be extrapolated eastward along the coast” of Long Island.

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