Cigarettes kill about 6 million people globally each year, making it the leading cause of preventable death in the world. Everyone knows that smoking is deadly, so the question remains: How do you prevent people from smoking?

Public health experts have a theory. If you change the way tobacco is packaged — by introducing plain packaging, without the brand, logos, and designs that entice consumers — you can reduce smoking rates. (The package features nothing but the product's name in plain text, along with graphic warnings about the health effects of smoking.) It's worked for Australia, the only country that currently mandates plain cigarette packaging. It could work for the rest of the world, too.

That's why the World Health Organization is asking countries to step up their efforts to curb tobacco use through this strategy. "Plain packaging reduces the attractiveness of tobacco products," WHO Director-General Margaret Chan said this week. "It kills the glamour, which is appropriate for a product that kills people."

Here's what cigarette packaging looks like in six countries.

1. Australia

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Australia is the only country that currently mandates plain cigarette packaging. One year after the plain-packaging law passed, the percentage of tobacco users who said they were trying to quit went up 7 percentage points, from 20 to 27 percent, the Australian Broadcasting Corporation reports.

2. America

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Tobacco companies don't have to abide by stringent advertising guidelines in America, according to Duke University. The required label — a warning from the U.S. Surgeon General — must be featured on the cigarette pack, but it is generally much smaller and less visible than warning labels you see in other countries.

3. United Kingdom

Cancer Research UK - cancerresearchuk.org

Cancer Research UK - cancerresearchuk.org

One of the latest countries to implement its own plain-packaging laws, the U.K. previously required packs to contain large, bold warning labels. They were more noticeable than the ones in America but still allowed tobacco companies to advertise. By May 2017, however, all cigarettes will have to conform with the plain-packaging standard you see above.

4. India

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"In October 2014, India brought in a new law that called for covering 85 percent of the cover of tobacco products with pictorial warnings, as compared to 40 percent now," Quartz reported.

5. France

French Health Ministry - tobaccolabels.ca

France's smoking rate is one of the highest in the world: 32 percent of men and 26 percent of women smoke in the country, Vox reported. Beginning in 2017, France will mandate plain cigarette packaging in a bid to reduce that rate.

6. Canada

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Canada's graphic warning labels are more pronounced than those in America. The county also recently voted to move forward with plans to require plain cigarette packaging in 2017, the Guardian reported.

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