Brazil's President, Jair Bolsonaro, has sanctioned a law making the use of masks in public obligatory during the coronavirus pandemic.
However, he has vetoed their use in shops, churches and schools.
In a social media broadcast, Mr Bolsonaro said people could have been fined for not wearing a mask at home.
He has refused to acknowledge the gravity of Brazil's Covid-19 outbreak, despite it having the world's second-highest numbers of cases and deaths.
The virus has infected almost 1.5 million people and killed 61,884 there since late February, according to data collated by Johns Hopkins University.
Even where mask use has been made obligatory not everyone has observed the rules, and enforcement is often pretty lax, our correspondent adds.
The bill passed by the Chamber of Deputies included an article saying that masks had to be worn by people in "commercial and industrial establishments, religious temples, teaching premises and also closed places where people are gathering".
On Friday, Mr Bolsonaro vetoed the article, arguing that it could lead to the violation of property rights.
He also vetoed another requiring the distribution of masks to the poor.