Air quality in Dimitrovgrad has stayed within limits after the accident at the Neochim plant on 11 October, the Haskovo regional environment inspectorate (RIOSV) said.

The "Rakovski" automatic monitoring station in the town measures ammonia, nitrogen dioxide, sulphur dioxide, fine dust particles (PM10) and ozone. None of the five readings is above the limit. The data cover the period from 00:00 on 11 October until the time the inspectorate released them.

The accident happened at about 9:50 at the unit that makes 60% nitric acid. According to RIOSV, a fault in a valve control set off an emergency shutdown. Nitrogen oxides escaped from the stack for two to three minutes.

Residents in the "Breathe, Dimitrovgrad" Facebook group posted photos and videos of a yellow-orange cloud over the plant. The plant operator told the authorities, and RIOSV inspectors carried out a check.

The plant had an earlier accident on 19 August, when ammonia leaked from a pipeline at the production site.