Furthermore,the air quality in cities is
often poor, due to pollution from traffic,
and the streets and public transport systems
are usually overcrowded.
在我知识范围内（虽然很小）
due to是介词
不能直接加上主词(pollution + systems)和动词(are)
应该用连接词because才对
是句子错还是我错了？

and the streets and public transport systems are usually overcrowded 这句是另一个完整的子句 and太多非常干扰

原来不是错误。谢谢，我看懂了！

due to跟because of可以互相替换意思差不多。这两个后面都是接原因，所以这句里面pollution from traffic就是这个"原因"，要把它们看成一组而非分开的三个词。如果是我我会这样标点：Furthermore, the air quality incities is often poor due to pollution from traffic;and the streets and public transport systems are usually overcrowded. 这样看比较顺。