our reporter michael wetzel went there to meet people tackling the city's smog.eporter: hanoi is so nice on the weekends. here, one can take a deep breath and relax. hanh dang and her family often come to hoan kiem lake, an oasis in the heart of the vietnamese capital. this barley sugar candy vendor certainly looks relaxed, probably more so now than during the work week. because on the weekend, the area around the lake becomes a pedestrian zone. hanh: i can also enjoy the wind blows with no mask, like every day. and all the weekends we go here, because e no traffic, , no caro motorbike. so easy, so relaxing. repoporter: on workdays, it's jt the opposite. hanoi has a population of more than seven million. the main mode of transport is the motorbike. and there are more and more cars as well. there are no reliable numbers as to exactly how many. but it's clear that traffic congestion is getting worse, and with it, the air. hanh dang rides a moped. she says it would take much too long to go to work by bus. she works for an international team working on ways to improv