The new city authorities in Uganda's capital have begun to enforce a 10-year-old law that bans the littering of Kampala's streets.
Since the new year, 40 people have been arrested, Kampala Capital City Authority's Peter Kawuju told the BBC.
Some have been ordered to clean out clogged drains as part of a community service sentences.
A BBC reporter in Kampala says roads usually littered or heaped with rubbish are impressively clean this week.
"People drop litter anywhere; people drop litter in drainage channels and then what happens is that the channels get clogged, there's flooding and it's also very unhygienic," Mr Kawuju, the KCCA's communications manager, told the BBC's Focus on Africa programme.
According to Uganda's state-owned New Vision newspaper, the maximum sentence for a person found littering is two months imprisonment, 20 hours of community service or a fine of 40,000 Ugandan shillings ($16, £10).
Television images of people being arrested this week for littering have upset some residents, who feel there should have been a warning about the move.
"The idea of having a clean city is good but I think the approach is not proper - there are too many laws people don't know about - at least you need to tell them that this is going to be imposed," one man in the city centre told the BBC.
Another passer-by said it was the responsibility of the KCCA - rather than taxpayers - to clean up the rubbish.
But other residents felt it was about time something was done about the filth.
"They should really be arrested and do community service," one woman shopper said.
The BBC's Joshua Mmali in Kampala, an opposition stronghold, says the KCCA was created last year to run services in the city, which the government says often become unmanageable because of party politics.
It is not guaranteed that the streets will remain litter-free, our reporter says.
Previous initiatives by the previous city authorities - for example, to clamp down on noise pollution or to enforce the wearing of crash helmets - have rarely been implemented beyond a fortnight, he says.
Does this initiative have your support? How is rubbish dealt with in your country? Should cities in other African nations clamp down on littering? Let us know your views.