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Tips for Individuals

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As we navigate the ongoing COVID–19 pandemic, despite greatly exaggerated declarations of its end, it is important to continue protecting ourselves. This guide breaks down actions you can take to keep yourself and your community safe from COVID at an event. Please note that while effective, these methods do not fully eliminate the possibility of contracting a COVID infection.

We recommend a few products as examples below. AFTERPARTY–19 and the guide authors declare they have no financial relationship with these companies.

Airborne Transmission of COVID–19

According to the World Health Organization, COVID–19 is an airborne virus that spreads in small liquid particles when an infected person coughs, sneezes, speaks, sings, or breathes. It can accumulate in the air in a poorly ventilated room. It is also possible for a person to contract COVID-19 after rubbing their eyes, nose, or mouth after touching a contaminated surface, though this is a less common route of transmission.

The virus can be transmitted even if you feel fine (asymptomatic or pre-symptomatic transmission).

Respirators & Masks

  • Use a well-fitted NIOSH approved valveless respirator such as an N95 (or better).
  • Respirators are the single most effective tool for preventing the spread of COVID–19 by protecting the wearer and others at the same time and by reducing both short and long range transmission. They can be reused.
  • Respirators trap infectious aerosols using mechanical properties and an electrostatic charge that pulls aerosols out of the air.
  • KN95s are N95s with looser fitting earloops instead of a headband, so they can leak more air.
  • Surgical masks are better than cloth masks because of their materials. Both are loose-fitting and leaky. Prefer a respirator to a mask.
    • Mask braces improve fit. Braces can be purchased or DIY. Tying a knot is another option.
    • Cloth masks are more effective if comprised of five tight woven cotton layers.

Masks work when you use them, they don’t when you don’t. Masking regularly in indoor spaces is most effective. If you need to unmask to eat or drink, try to do so outdoors or near a window or air filtration system. You can also use SIP valves for drinking indoors. Masks work better than you think.

Air Cleaning

Reducing the concentration of infectious aerosols in crowded outdoor or indoor spaces reduces the risk of long range (but not short range) and/or time delayed transmission (where someone can become infected by entering an appearently empty room).

  • Your options are somewhat limited as an attendee, but try to stick to outdoor spaces, open windows, and turn on air filters if they are around.
  • Handheld HEPA filters provide a way to filter air closest to you in public spaces, but are too small to filter a room.
  • Pay attention to carbon dioxide monitors if they are posted. If the concentration exceeds 1000 ppm in the absence of air filtration, you may want to open a window or leave.
  • Bring a HEPA filter or Corsi-Rosenthal box to your hotel room.


  • Pre-event testing, ideally within 24 or 48 hours before, helps prevent transmission at the event. Post-event testing helps you know whether to isolate, access treatment, and take it easy.
  • There's two test types: cheap Rapid Antigen Tests (RAT) and highly sensitive Nucleic Acid Amplification Tests (NAAT) (aka "molecular test" or PCR). Positive RATs are almost always right, even if the line is faint. Negative RATs do not exclude COVID–19.
  • Post-event, use a rapid test immediately if sick or 5 days after otherwise. If negative, test again after 48 hours. If you were exposed and twice negative, use a third test after 48 hours. (CDC)
  • You can get four free rapid antigen tests from the government.

Sanitizers, Sprays, and Mouthwash

  • While COVID-19 is primarily airbone, it's always a good idea to wash your hands. Alcohol or skin friendly hypochlorous acid based sanitizers can kill COVID-19 on hands and surfaces. (EPA)
  • Nasal washing with sterile saline may reduce viral load dramatically and the risk of complications.
  • After exposure, using mouthwash containing Cetylpyridinium Chloride (CPC) or Ethyl Lauroyl Arginate (ELA / LAE) may help prevent infection and also potentially reduce viral load and risk of severe illness during acute infection. It also keeps your breath (and mask) fresh!


  • Carpooling—Test passengers beforehand. Weather permitting, keep the windows down, and keep your masks on. A portable air filter may help.
  • Public Transit—Distance, keep your mask on, and bring sanitizer.
  • Air Travel—Wear a mask in terminal and plane, use sanitizer, and eat prior to your flight. The highest danger is when the engine is off as air filters are off. Point air conditioning toward aisle or other rows.
  • Consider using a saline nasal wash and CPC mouthwash at your destination.

Stay updated on vaccines & boosters!

Recommendations for Event Organizers

Individuals are relatively limited in the kind of interventions they can perform and it's a lot to put all the weight of having a safe event on individual attendees who might be immunocompromised or have visible or invisible health issues or disabilities. Event organizers can make a huge difference in safety and relieve pressure on guests by adopting one or more of the below concepts. Infectious disease, particularly the airborne kind, can only be effectively handled at the community level. Shared air is a shared problem.


  • The more attendees wearing any mask the safer your event. To achieve high compliance, you need to provide availability, social proof, and clear directions.
  • Mandates Work. Even with enforcement as light as door checks and periodic reminders, some crowds will acheive close to 100% compliance. Regardless of whether you reach that goal, a mandate will increase the percentage of masked attendees.
  • If a mandate is not workable, a masking recommendation will also increase the masked percentage, but many fewer as all the pressure to make a decision is put on the individual.
  • Bring free respirators to give to attendees. Prioritize N95s and KN95s respirators, but also have some surgical masks since someone with a big beard can't wear a respirator.
  • COVID–19 can transmit outdoors, especially in large crowds, so having a masking recommendation is still a good idea for outdoor events.

Air Cleaning

Reducing the concentration of infectious aerosols in crowded outdoor or indoor spaces reduces the risk of long range (but not short range) and/or time delayed transmission (where someone can become infected by entering an apparently empty room).

  • Wind (when outdoors), open windows, high grade air filters, upper room germicidal UV-C, and the emerging technology of Far UV-C lamps all dilute, remove, or inactivate COVID–19 aerosols. You should achieve at least five air change equivalents per an hour for reasonable efficacy.
  • In poor weather, open windows and outside activities become problematic, so filtration or inactivation of the virus is necessary.
  • In small to medium sized rooms, it is economical to improve indoor air quality via DIY Corsi-Rosenthal boxes or commercial HEPA filters. There are also PC-fan based low-noise, low-energy, high throughput filter boxes commercially available.
  • Consider upgrading your building's HVAC systems to the new ASHRAE Standard 241, Control of Infectious Aerosols.

Carbon Dioxide (CO2) Monitoring

Carbon dioxide is exhaled by humans during respiration, the same process that generates virus laden aerosols. It is a reasonable proxy for how much rebreathed air is present in a room and comparatively cheap to monitor. The November 2023 baseline measurement is 418 ppm and increases a few points a year mainly due to human emissions.

  • A carbon dioxide monitor should be posted away from windows or doors and at least a few feet away from people along with directions for interpretation so that people can see at a glance whether the air is substantially rebreathed.
  • Set an Action Threshold—A reading above 1000 ppm should trigger the introduction of fresh air or the subtraction of participants, with a goal of driving carbon dioxide levels below 800 ppm (lower is better). If participants are exercising, talking loudly, or singing, 800 ppm is a more appropriate threshold for action.
  • At 800 ppm, 1% of each breath is rebreathed (if the carbon dioxide is not from nearby combustion).
  • Air filtering or sterilizing techniques will reduce viral concentration without affecting the level of carbon dioxide, which may affect your action threshold, though above 1000 ppm humans start to become affected by the carbon dioxide itself.

Testing Policy

Ask attendees to test within a day or two before attending the event. You can make this verified or self-certified.

  • Verfied—Attendees submit an image of their test results to event staff with today's date in the background.
  • Self-Certified—Attendees are told to test, but there's no checking by event staff.
  • Ask attendees to test after the event if they are symptomatic or after five days for asymptomatic testing.


  • Host the event outdoors if possible. Spaces enclosed on three sides are still relatively risky as air cannot move easily.
  • Consider including a virtual or hybrid option.
  • Put food and drink in a separate well ventilated room so vulnerable people can opt-out of unnecessary exposure.

Exposure Notifications

If you learn someone had COVID–19 at your event, letting attendees know encourages them to test, mask, and quarantine as they are able to. This may not eliminate further spread, but it will likely reduce it.

  • If an attendee contracts a suspected, probable, or confirmed case of COVID–19, let the rest of your attendees and event staff know without revealing that person's identity.
  • You may need to gather attendee contact information in order to do so, such as by an iPad or guest book at the door.
  • Make sure to get consent to do the alert from the person that became ill and consent to contact the other attendees.
  • Using AFTERPARTY–19 to collect COVID–19 status reports can help as all users must consent to make their submissions public and are not able to be re-identified. The soon as someone reports themselves as positive or a suspected case, sound the alert.
  • In your notification, include resources about how to manage an acute COVID–19 infection and how to recognize Long COVID (sometimes called Post-Acute Sequale to COVID–19 or PASC).

Integrate AFTERPARTY–19

Use this app to facilitate pre-testing, get timely warnings, and track how well your mitigations are working.

  • Create an event and send the link to attendees at least a few days before the event so they can anonymously report pre-tests.
  • If your event is one or more days, it is especially likely it may benefit from the timely warning feature if an attendee becomes ill part-way through and reports their status.
  • Each event page has its own QR code at the bottom of the page, print it out and give it to attendees at the door.
  • Print out our double sided one-pager individual safety guide to hand out at the door or share the link to this page.
  • Ask attendees to report their COVID–19 status on the event immediately after, and remind them a few days after the event.


A relatively recent vaccine can help prevent transmission (the COVID–19 vaccines never fully stop transmission), but the effect wears off over time. It's a valuable additional layer to reduce transmission and protect people that do get sick. Remember that for immunocompromised people (2.8 in 100 people), the vaccine may not help them and they rely on others to protect them.

  • The main effect on transmission is from a high titer of neutralizing antibodies, which peak and then fall to a maintainence level over a few months which is unfortunately too low to prevent transmission. As variants diverge, the efficacy of these antibodies is reduced as well until the immune system is retrained via infection (which risks organ damage and death and has adverse impacts on some immune system components) or updated vaccination.
  • It takes 2 weeks for a new vaccine to become protective, boosters may be moderately faster.
  • All attendees will benefit from vaccination as it will reduce the incidence of severe disease.
  • Your policy options are:
    • Require up-to-date vaccination and boosters.
    • Require full vaccination.
    • Recommend vaccination.
    • Provide information about available vaccines and where to get them locally to attendees.
  • See CDC information on vaccinations.

Safety Tips © 2023 AFTERPARTY-19, licensed under Creative Commons Attribution 4.0 International.