More than 150 nightclubs, restaurants and bars in Brazil have been deemed to be unsafe and closed by authorities.
Sunday's fire in a club in the southern city of Santa Maria, which killed 236 people, led to inspections of venues across the country.
There are temporary closures in Rio de Janeiro, Sao Paulo, the capital, Brasilia, and many smaller cities.
Investigators say lives could have been saved if regulations had been properly observed.
A 20 year-old man died in hospital, becoming the 236th victim of the fire, authorities said on Friday.
After four days of inspections, authorities in Rio de Janeiro said that 199 of the 209 venues they inspected had irregularities.
Of those, 127 have been temporarily shut and their owners given 30 days to make alterations.
In the capital, Brasilia, 16 nightclubs were closed, after authorities found they were missing licence documents.
In Brazil's biggest metropolis, Sao Paulo, safety visits found irregularities in 24 out of 39 venues.
The problems range from obstructions at fire exits and problems with fire extinguishers to a lack of fire evacuation plans, alarms and emergency lights.
The pattern was the same in many smaller cities across Brazil.
Earlier this week, the governor of Sao Paulo state, Geraldo Alckmin, ordered tighter inspections of all venues, including nightclubs, cinemas and theatres.
A so-called Maximum Prevention operation was launched on Wednesday evening.
The Santa Maria police chief in the southern state of Rio Grande do Sul has blamed Sunday's fire on cheap fireworks meant for outdoor use.
Marcelo Arigony, who is also heading the investigation, said the band playing in the nightclub had chosen not to buy more expensive indoor flares.
Investigators also blamed the use of unsafe acoustic insulation for the toxic fumes that led to many of the deaths.
One of the four people detained is the co-owner of the nightclub.
A member of the band, Gurizada Fandangueira, suspected of starting the fire with a flare, has also been arrested.
The fire has prompted widespread domestic concern about Brazil's ability to host major sporting tournaments in the next four years.
The 2014 World Cup is set to be hosted in 12 Brazilian cities, while the 2016 Olympics are to take place in Rio de Janeiro.
Brazil's Congress is set to revise legislation in an attempt to strengthen safety regulations ahead of the World Cup.