WASHINGTON — In recent decades, the United States and Europe have gone to considerable lengths to mandate cleaner, more efficient cars at home. But at the same time, they are shipping millions of their oldest and worst-polluting vehicles to poorer countries overseas in a largely unregulated trade that now poses serious health and environmental hazards, the United Nations warned on Monday.
The report, by the United Nations Environment Program, is the most detailed look yet at the global trade in secondhand cars, which has historically attracted little scrutiny. Between 2015 and 2018, the report found, the United States, the European Union and Japan exported 14 million used passenger cars abroad, with 70 percent ending up in low-income countries in Africa, Eastern Europe, Asia, Latin America and the Middle East.
In theory, this trade can be beneficial: Once older cars are no longer desirable to buyers in wealthy nations, they can have a second life as an affordable transportation option in other countries. In countries like Kenya and Nigeria, more than 90 percent of cars bought today are secondhand imports.
But in practice, the report found, many of the cars exported to low-income countries don’t meet even minimum standards for air pollution and are often unsafe to drive. There are few rules in place to govern the quality of the vehicles. In the Netherlands, investigators recently determined, some exported cars have had their pollution controls removed and harvested for the valuable metals they contain, before being shipped abroad.
“What we found is not a pretty sight,” said Rob De Jong, an author of the report and head of the United Nations Environment Program’s Sustainable Mobility Unit. “Most of these vehicles are very old, very dirty, very inefficient and unsafe.”
If left unsupervised, the global trade in used vehicles could have stark consequences for both climate change and public health in the decades ahead, the report’s authors said.
Today, there are about 1 billion cars on the road globally. That number is projected to double by 2050, with much of the growth coming from sales of secondhand vehicles in lower-income countries. Transportation already accounts for one-quarter of humanity’s carbon-dioxide emissions, which are rapidly heating the planet. And in many African cities, cars and trucks have become a dominant source of outdoor air pollution, which already kills more than 3 million people worldwide each year.
A few countries have started taking steps to crack down on the oldest and dirtiest used cars: Kenya, a rapidly growing market, now accepts only imports of vehicles younger than 8 years old, mainly from Japan. As a result, its vehicle fleet is about one-third more fuel-efficient than that of neighboring Uganda, which only last year set an age limit of 15 years for its imported cars.
But such restrictions are rare.
The report looked at 146 countries that import used cars and concluded that 86 of them had “weak” or “very weak” laws around the age or environmental performance of used vehicles entering their markets. While the report’s authors don’t call for a ban on the trade of used cars, they do recommend that countries do more to coordinate on minimum standards.
Such rules can have a big effect. In the European Union, cars built after 2005 had to comply with so-called Euro 4 standards, which aimed to slash the most harmful pollutants in car exhaust by more than 70 percent compared with older models. These pollutants, such as fine particulate matter and nitrogen oxides, have been linked to increased risk of heart attacks, lung cancer and asthma. Europe further tightened its pollution rules for new cars in 2009 and 2014.
Most used cars shipped to Africa still don’t meet these standards, although 15 West African nations, including Nigeria and Ghana, recently agreed to adopt the equivalent of Euro 4 rules for all imported cars starting in 2021.
Researchers have also found that aging cars with lots of wear and tear can be less safe to drive and more likely to crash. The report noted that countries with weak restrictions on imports, such as Nigeria or Zimbabwe, have particularly high rates of traffic deaths, while countries like Chad that have limited imports of very old cars see considerably fewer fatalities.
Even so, new regulations can be politically contentious. In some African nations, officials have expressed concern that overly tight restrictions could make cars unaffordable for many people, said Jane Akumu, an expert on sustainable transportation in Africa at the United Nations Environment Program.
However, Ms. Akumu added, countries like Ivory Coast that have restricted trade in older and dirtier secondhand cars have so far not seen imports fall. “Instead, they’ve seen a shift toward cleaner vehicles coming in,” she said.
Rich countries could also conduct more careful quality checks of their exports, the report said. On Monday, regulators in the Netherlands released the results of an investigation showing that most of the secondhand cars the country exported to Africa in 2018 lacked valid certificates of roadworthiness, while some vehicles had their catalytic converters, which filter out air pollutants, stripped of valuable metals like platinum.
“So far, we’re the only European country that’s done this sort of in-depth investigation,” said Marietta Harjono, lead author of the investigation in the Netherlands. “And we don’t believe the quality controls are better elsewhere.”
If managed properly, the trade in secondhand cars could be a boon for efforts to fight climate change. In the United States and Europe, automakers are currently ramping up production of cleaner hybrid and electric vehicles. Once these cars trickle through wealthier markets, they could become increasingly affordable options for developing countries, too.
Sri Lanka, for its part, recently imposed higher taxes on heavily polluting diesel imports while cutting taxes for cleaner vehicles. As a result, the report said, the country now has the highest number of hybrid and electric vehicles per capita of any nation in the world.
“If we get these policies right,” said Mr. De Jong, “it could have massive benefits for air pollution and climate change worldwide.”