Airborne vs. Aerosol vs. Droplet: What's the Difference?

Victor J. Blue/Stringer/Getty Images
Victor J. Blue/Stringer/Getty Images

COVID-19 has introduced several new terms to the national lexicon. In addition to phrases like social distancing, self-quarantine, and N95 respirator, you may have seen the word airborne popping up more in recent weeks. It usually appears in discussions concerning how the novel coronavirus that causes COVID-19 is transmitted—a question that's still debated by health experts. So what exactly does it mean when a pathogen is airborne, what do droplets and aerosol have to do with it, and which of these terms apply to the new coronavirus?

What are droplets?

We know that there are at least two ways to catch the new coronavirus: by coming in close contact with infected individuals and touching contaminated objects and surfaces. In both cases, the root of the transmission is often a cough or sneeze. When someone with COVID-19 coughs—which is a hallmark symptom of the disease—they send a spray of mucus and saliva droplets flying from their mouths. These tiny, sometimes invisible droplets, measuring between five and 10 micrometers in diameter, contain particles of the virus. Coughing into a shirt sleeve or mask can catch a lot of these droplets, but with nothing to block them, many will land on objects and people in the immediate vicinity. This is why a sick person is more likely to infect more people standing elbow-to-elbow with them in crowded subway car than they are keeping a 6-foot distance from others in a spacious park.

You don't need to be touching someone to contract coronavirus from them. If someone is standing directly behind you in line at the grocery store, they can infect you through the droplets in a sneeze or cough. But while these droplets technically travel through the air, that doesn't automatically make COVID-19 an airborne disease—at least not according to the definition of the word used by health officials. In order to understand what airborne really means, you need to know about aerosols.

What are aerosols?

Saliva and mucous droplets are heavier than air, which means gravity starts pulling them—and whatever viral particles they contain—towards the ground as soon as they leave someone’s body. By the time someone walks out of a room, any droplets they may have emitted have likely already settled on the floor or nearby surfaces—so usually, you don’t need to worry about breathing in those droplets if you’re social distancing correctly.

Aerosols are a different story. They form when smaller droplets evaporate faster than they fall to the ground, leaving nuclei measuring less than five micrometers in diameter. Without heavy liquids dragging them down, virus particles from these evaporated droplets are able to float through the air for up to half an hour. When a virus travels via aerosols, it’s possible to contract it by entering an empty room that a sick person was in several minutes earlier. This transmission via free-drifting aerosols is how the World Health Organization defines an airborne disease.

Is the new coronavirus airborne?

If the novel coronavirus is capable of spreading this way, it would mean that social distancing guidelines are only addressing part of the threat. But as of now, there’s little data to suggest that aerosol transmission is a real concern with COVID-19. “According to current evidence, COVID-19 virus is primarily transmitted between people through respiratory droplets and contact routes,” WHO says. “In an analysis of 75,465 COVID-19 cases in China, airborne transmission was not reported.”

The virus still very new, and while airborne transmission has yet to be confirmed, that doesn’t mean it can be ruled out completely. Some health experts have expressed concern over discounting aerosol spread so early and believe it’s a possibility we should be paying closer attention to.

Though there may be a small chance of the novel coronavirus wafting in ambient air, it's not unsafe to open a window or go outside. Airborne viruses are more likely to spread in rooms with poor ventilation than they are outdoors, so allowing air to circulate in your home can actually help prevent the spread of disease. Plus, getting fresh air and exercise is important for staying mentally and physically well in stressful situations.

When leaving the house, just keep some safety precautions in mind. Maintain at least a 6-foot distance from others to protect yourself from droplet transmission, and wash your hands thoroughly after touching surfaces that may be contaminated. Wearing an N95 respirator is the best way to prevent airborne infection, but because supplies are limited, new masks should be reserved for especially vulnerable people like healthcare workers. Homemade cloth masks and surgical masks aren’t built to filter out smaller airborne particles, but they can stop larger droplets from splashing onto your face, and just as importantly, stop infected wearers from spreading droplets to others.

13 Father's Day Gifts for Geeky Dads

Amazon/Otterbox/Toynk
Amazon/Otterbox/Toynk

When in doubt, you play the hits. Watches, flasks, and ties are all tried-and-true Father’s Day gifts—useful items bought en masse every June as the paternal holiday draws near. Here’s a list of goodies that put a geeky spin on those can’t-fail gifts. We’re talking Zelda flasks, wizard-shaped party mugs, and a timepiece inspired by BBC’s greatest sci-fi series, Doctor Who. Light the “dad” signal ‘cause it’s about to get nerdy!

1. Lord of the Rings Geeki Tikis (Set of Three); $76

'Lord of The Rings' themed tiki cups.
Toynk

If your dad’s equally crazy about outdoor shindigs and Tolkien’s Middle-earth, help him throw his own Lothlórien luau with these Tiki-style ceramic mugs shaped like icons from the Lord of the Rings saga. Gollum and Frodo’s drinkware doppelgängers each hold 14 ounces of liquid, while Gandalf the Grey’s holds 18—but a wizard never brags, right? Star Wars editions are also available.

Buy it: Toynk

2. Space Invaders Cufflinks; $9

'Space Invaders' cufflinks on Amazon
Fifty 50/Amazon

Arcade games come and arcade games go, but Space Invaders has withstood the test of time. Now Pops can bring those pixelated aliens to the boardroom—and look darn stylish doing it.

Buy it: Amazon

3. Legend of Zelda Flask; $18

A 'Legend of Zelda' flask
Toynk

Saving princesses is thirsty work. Shaped like an NES cartridge, this Zelda-themed flask boasts an 8-ounce holding capacity and comes with a reusable straw. Plus, it makes a fun little display item for gamer dads with man caves.

Buy it: Toynk

4. AT-AT Family Vacation Bag Tag; $12

An At-At baggage tag
ShopDisney

Widely considered one of the greatest movie sequels ever made, The Empire Strikes Back throws a powerful new threat at Luke Skywalker and the Rebellion: the AT-AT a.k.a. Imperial Walkers. Now your dad can mark his luggage with a personalized tag bearing the war machine’s likeness.

Buy it: ShopDisney

5. Flash Skinny Tie; $17

A skinny Flash-themed tie
Uyoung/Amazon

We’ll let you know if the Justice League starts selling new memberships, but here’s the next best thing. Available in a rainbow of super-heroic colors, this skinny necktie bears the Flash’s lightning bolt logo. Race on over to Amazon and pick one up today.

Buy it: Amazon

6. Captain America Shield Apron; $20

A Captain America themed apron
Toynk

Why let DC fans have all the fun? Daddy-o can channel his inner Steve Rogers when he flips burgers at your family’s Fourth of July BBQ. Measuring 31.5 inches long by 27.5 inches wide, this apron’s guaranteed to keep the cookout Hydra-free.

Buy it: Toynk

7. Doctor Who Vortex Manipulator LCD Leather Wristwatch; $35

A Doctor Who-themed watch
Toynk

At once classy and geeky, this digital timepiece lovingly recreates one of Doctor Who’s signature props. Unlike some of the gadgets worn on the long-running sci-fi series, it won’t require any fancy chronoplasm fuel.

Buy it: Toynk

8. Wonder Woman 3-Piece Grill Set; $21

Wonder Woman three-piece gill set
Toynk

At one point in her decades-long comic book career, this Amazon Princess found herself working at a fast food restaurant called Taco Whiz. Now grill cooks can pay tribute to the heroine with these high-quality, stainless steel utensils. The set’s comprised of wide-tipped tongs, a BBQ fork, and a spatula, with the latter boasting Wonder Woman’s insignia.

Buy it: Toynk

9. Harry Potter Toon Tumbler; $10

Glassware that's Harry Potter themed
Entertainment Earth

You can never have too many pint glasses—and this Father’s Day, dad can knock one back for the boy who lived. This piece of Potter glassware from PopFun has whimsy to spare. Now who’s up for some butterbeer?

Buy it: EntertainmentEarth

10. House Stark Men’s Wallet; $16

A Game of Thrones themed watch
Toynk

Winter’s no longer coming, but the Stark family's propensity for bold fashion choices can never die. Manufactured with both inside and outside pockets, this direwolf-inspired wallet is the perfect place to store your cards, cash, and ID.

Buy it: Toynk

11. Mr. Incredible “Incredible Dad” Mug, $15

An Incredibles themed mug
ShopDisney

Cue the brass music. Grabbing some coffee with a Pixar superhero sounds like an awesome—or dare we say, incredible?—way for your dad to start his day. Mom can join in the fun, too: Disney also sells a Mrs. Incredible version of the mug.

Buy it: ShopDisney

12. Star Wars phone cases from Otterbox; $46-$56

Star Wars phone cases from OtterBox.
Otterbox

If your dad’s looking for a phone case to show off his love of all things Star Wars, head to Otterbox. Whether he’s into the Dark Side with Darth Vader and Kylo Ren, the droids, Chewbacca, or Boba Fett, you’ll be able to find a phone case to fit his preference. The designs are available for both Samsung and Apple products, and you can check them all out here.

Buy it: Otterbox

13. 3D Puzzles; $50

3D Harry Potter puzzle from Amazon.
Wrebbit 3D

Help dad recreate some of his favorite fictional locations with these 3D puzzles from Wrebbit 3D. The real standouts are the 850-piece model of Hogwarts's Great Hall and the 910-piece version of Winterfell from Game of Thrones. If dad's tastes are more in line with public broadcasting, you could also pick him up an 890-piece Downton Abbey puzzle to bring a little upper-crust elegance to the homestead.

Buy it: Hogwarts (Amazon), Winterfell (Amazon), Downton Abbey (Amazon)

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(Almost) Everything You Need to Know About Tear Gas

Londoners undergo a gas exercise for civilians, using tear gas, in 1941.
Londoners undergo a gas exercise for civilians, using tear gas, in 1941.
Keystone/Getty Images

Protests against racism and police brutality, triggered by the tragic killing of George Floyd at the hands of a Minneapolis police officer, have emerged in every major American city and in countries around the world. In many places, the protestors have been met with heavy resistance from police wielding tear gas—a chemical weapon that dates back to the early 20th century.

What is tear gas?

Tear gas isn’t one specific chemical and, despite the name, it’s usually not even a gas. There are a few different compounds that are used as “lachrymatory agents.” Most of them are solids at room temperature, and get mixed with liquid or gas dispersal agents for use.

Where did tear gas come from?

Tear gases are something that militaries have been messing around with since World War I. Both France and Germany developed and deployed lachrymatory irritants in battle, but there was evidently a bit of a learning curve. According to the U.S. Army’s Combat Studies Institute, the Germans fired some 3000 tear gas shells during one day of fighting in 1914, but the British troops on the receiving end “suffered no ill effects and never suspected they were under chemical attack.”

Shortly thereafter, the Germans had gotten a better handle on things and were using tear-inducing gases to great effect. In 1916, they fired 2000 shells into a French trench system and 2400 French soldiers—blinded, coughing, and crying—quickly found themselves surrounded by German troops in protective goggles.

CS gas would come a few decades later. Its active component, 2-chlorobenzylidene malononitrile, was synthesized by American chemists Ben Corson and Roger Stoughton in 1928 (the CS stands for Corson and Stoughton). Tear gas using it was developed and tested during the 1950s and '60s.

What does tear gas do?

Tear gases irritate the mucous membranes of the eyes, nose, mouth, and lungs, and cause tearing, coughing, burning, and stinging sensations; chest tightness, and difficulty breathing. At higher concentrations, exposure can cause stomach irritation leading to vomiting and diarrhea.

According to German toxicologist Uwe Heinrich, dispersing the gas at a concentration of 1 mg per cubic meter will cause symptoms of irritation. From there, things go sour pretty quickly. A concentration of 10 mg per cubic meter can force trained soldiers to retreat from an area. Ten to 20 mg/m3 or higher can cause serious injury or, depending on the victim and conditions of exposure, death. In one incident reported in a Swiss medical journal, an otherwise healthy adult man was exposed to a tear gas grenade containing just one gram of CS while inside a building. He quickly developed toxic pulmonary edema, a condition where excess fluid collects in the air sacs of the lungs and causes difficulty breathing, and recovered only after weeks of medical treatment.

Being hit with tear gas may make you more susceptible to respiratory illness, like influenza or COVID-19, later on, Duke University anesthesiology professor Sven-Eric Jordt tells OneZero. Prolonged exposure to tear gas in an enclosed setting can cause long-term injuries, including glaucoma, blindness, respiratory failure, and even death.

And, because tear gas is actually a solid, its particles can coat any surface they fall on, such as clothing, food, animals, and plants. The extent of environmental damage associated with tear gas is not well studied, but the chemical likely contributes to air pollution as well. It may further burden Black and Latino communities disproportionately saddled with environmental pollution.

Shouldn’t tear gas be illegal?

It is, kind of. Tear gases were used in warfare throughout most of the 20th century until 1993, when the Chemical Weapons Convention banned the production, stockpiling, and use of chemical weapons in battle. The international treaty doesn’t apply to nations’ domestic law enforcement, though, so police officers in the United States are free to spray it at civilians, typically as a means of crowd dispersal.

How do you treat tear gas exposure?

If you’re outside, the best antidote to any breathing problems is fresh, untainted air, and time. For high-dose exposure or exposure in enclosed spaces, bottled oxygen or certain asthma medications may be administered to ease difficulty breathing. Any exposed skin should be washed with soap and water and eyes should be flushed with sterile water or saline solution. Some protestors use a solution of baking soda and water on the theory that the basic sodium bicarbonate can weaken the molecules in tear gas and counteract its effects. Others have used milk or milk of magnesia to fight the burning sensation in pepper spray; experts caution that these fluids aren't sterile and could cause infection.

This story has been updated for 2020.