Editor’s Note: Jennifer Lee is a clinical associate professor of emergency medicine at The George Washington University. She is a former Deputy Under Secretary for Health at the Department of Veterans Affairs and the former Medicaid Director for the Commonwealth of Virginia. Follow her @DrJenLee. Opinions expressed in this commentary are her own. View more opinions at CNN.

CNN  — 

If you’re venturing outside this holiday weekend, there is now more evidence than ever that wearing a face mask may be the single most important step you can take to protect yourself and your loved ones.

Jennifer Lee

Here are seven reasons why you don’t want to leave home without a mask:

Masks protect you and your family and friends. Though it is possible to get Covid-19 by touching a contaminated surface or object and then touching your mouth, nose or eyes, it is now clear that this is not the primary way that the coronavirus spreads. The virus primarily spreads through close contact with an infected individual via respiratory droplets that are emitted while coughing, sneezing, singing, laughing, talking, or even just breathing. Wearing a face mask is one of the best ways for infected individuals to keep those droplets contained, and for those who are healthy, a mask can also offer some protection from breathing them in.

In one review article published in the Lancet last month, researchers analyzed 172 studies from 16 countries to better understand the effects of physical distancing, face masks, and eye protection. Face masks were shown to reduce the risk of infection from about 17% to 3%. In another study, researchers found that a cough emitted with no mask traveled up to 12 feet. With a stitched mask made from two layers of quilting fabric, however, droplets traveled only 2.5 inches from the face. Because people can spread the virus before they know they are infected, it is most effective for everyone to wear a mask in the presence of other people.

Masks slow the spread. The US is in the midst of a dangerous resurgence of Covid-19 that Dr. Anthony Fauci, the nation’s top infectious disease expert, said could lead to as many as 100,000 new cases a day. At least 23 states have already paused reopening plans and eight states have record numbers of new cases. What can we do? Between April 8 and May 15, states that mandated face masks in public saw a greater decline in daily Covid-19 growth rates than states that did not. An estimated 230,000 to 450,000 infections were likely prevented by these mandates.

Masks save lives. One study compared death rates across 198 countries and found that those countries with cultural norms or government policies supporting mask-wearing in public had lower per-capita mortality rates than countries that didn’t. Consistent with these findings, a recent update to the Institute for Health Metrics and Evaluation model forecasts that more than 23,500 lives could be saved by October 1 if 95% of people in the US wore masks.

Masks can help businesses stay open. People face a higher risk of infection when they are indoors – an important consideration as businesses are trying to reopen. One compelling example illustrates how universal mask-wearing can protect employees and customers, even when they are in close proximity. In late May, two hair stylists in Missouri who were infected with the coronavirus came in close contact with 140 clients. Despite fears of an outbreak, none of their contacts tested positive. What might have made a difference? The two hair stylists wore masks, as did all their customers. Local health officials credit the use of protective gear with preventing a potential outbreak.

Masks reduce your risk when traveling. It can be impossible to maintain a safe distance from other people when you’re flying or traveling by train or bus. In these situations, masks are essential to protect yourself and others from getting infected. It’s risky to travel these days, especially as cases spike across the country, but if you absolutely have to, the single most important thing you can do to protect yourself and others while traveling is to wear a mask.

Masks protect essential workers. More than 90,000 health care workers have been infected and 500 have died from Covid-19 in the US. Countless others who work in mass transit, grocery stores, delivery services and other vital industries have succumbed to the virus. Without essential workers, who are often from communities of color, the disruption to our lives and economy would undoubtedly have been much worse. The simple act of wearing a mask while in public honors their sacrifice by showing that you care about their health. It is the least we can do.

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    Masks can help us move forward as a country. As other countries like South Korea and Taiwan have shown, universal mask-wearing is one of the simplest, most effective measures we can take to keep the virus at bay and help our economy thrive again. This July 4, if you’re feeling patriotic or nostalgic for the way things were, wearing a face mask is one easy way you can help the nation fight this virus.