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.