The city of Beijing issued a red alert for air pollution last week, the highest warning to residents to exercise extreme caution when going outdoors. They're technically not even safe indoors unless residents purchase expensive air filters. At least 70 Chinese cities were under similar alerts last week.

Meanwhile, in India, pollution was so bad in New Delhi that it registered at double the maximum "hazardous" measurement on the city's air quality index. The city government no longer had a vocabulary word capable of describing how dangerous the air was. New Delhi is, by far, the most heavily polluted city on Earth.

These aren't just domestic health hazards. They are trade-fairness issues.

For all of President-elect Donald Trump's emphasis on tariffs to increase America's manufacturing competitiveness, he ignores the environmental factors at the heart of China's and India's ability to undercut American manufacturers at every turn.

As uncomfortable as it might be for Trump to become a champion of environmental enforcement, he must embrace the notion that controls are necessary for human survival. Unilateral environmental enforcement by the United States and other Western nations will be useless if developing countries continue to pollute with reckless abandon. The idea shouldn't be to relax American controls but to pressure China, India, Brazil and Russia, among others, to dramatically tighten theirs.

This has been a fundamental flaw of various international free-trade accords, including the North American Free Trade Agreement that went into effect with Mexico and Canada in 1994. That year, Mexico City held title to the most polluted city on the planet. The air was so bad that officials considered proposals to dig tunnels in the sides of surrounding mountains and installing gigantic exhaust fans.

NAFTA contained yawning gaps on environmental enforcement, strengthening Mexican factories' ability to produce goods much more cheaply than their U.S. and Canadian counterparts. Not only could Mexican producers easily befoul water and air but their energy costs were lower because the country's state-owned oil company didn't have to meet anywhere near the same standards as its U.S. counterparts.

Power plants that provided energy to Mexico's maquiladora industries near the U.S. border burned high-sulfur coal. The dirty air wafted across the border into the Grand Canyon and Big Bend National Park in Texas. Mexico-produced smog at times became so heavy that U.S. factories and power plants along the border were forced by the Environmental Protection Agency to curtail production because border-area pollution increments were already exceeded.

Trump suggests easing environmental restrictions on American coal plants to help boost blue-collar employment. But unless he's willing to turn American cities into the same lethal time bombs as Beijing and New Delhi — something the American population would never accept — he's got to find a better way.

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