The steel factory ArcelorMittal Zenica is owned by the world largest steel producer – the ArcelorMittal Corporation. The factory, originally state-owned was privatized and Arcelor-Mittal is now the main shareholder, with the government owning a symbolic share.
In July 2008, the factory restarted integrated steel production after the facilities were damaged and closed down during the Yugoslavian civil war in the 1990s. ArcelorMittal Zenica produces hot rolled products (rebars, wire rod, mesh, lattice girders, and classic construction armature) mainly for the Balkan, EU and North African markets. The town is located in a small, narrow valley – 14 kilometres from Janić to Vranduk, and is in between two mountains that are less than 2 kilometres apart. Because of this from November to February, a toxic cloud forms over the city which traps all the substances rising from the chimneys of steel plants and the other factories. Since 2008, the analyses of air quality showed that pollution in Zenica was exceeding EU and Bosnia and Herzegovina standards, often reaching alarming levels. An increase in the number of cancer diseases among the population of Zenica has also been recorded according to a 2011 report on the population's health, conducted by the Cantonal Institute for Public Health. The report revealed some alarming statistics: In the period between 2002 and 2011, tumors have become the second leading cause of death among residents with a striking 20%. According to the report, the number of cancer patients increased from 892 persons in 2002 to 1,888 in 2010 and 1,774 in 2011. The number of cancer patients has increased by the hundreds each year, and especially from 2007 onward, i.e. since the full production of steel was resumed  however there are diverging opinions about how much of the epidemic can be blamed on the steel plant.
In December 2012, after a several years of sending demand letters for installation of filters in the plants, the citizens of Zenica organised a large protest attended by several thousand people. Citizens demand filters for the smoke stacks to reduce toxic gases and heavy metals; as well as an independent, publicly- controlled center for monitoring emissions led by the local university and the local government. The latter would be supplemented by a public mechanism of measuring the emissions as well as an alarm system that would alert the population whenever emissions exceed safety limits . On the 15th of November 2013, ArcelorMittal, has finally installed a filter in blast furnace and proudly announced this would lower their emissions below the acceptable levels. In this way the company admitted they have been breaking the law over the years. They did this at the official ceremony attended by representatives of cantonal and local authorities in charge of making and enforcing those laws. Citizens considered ArcelorMittal should not be acknowledged for installing the filter, as the damage has already been done. However, the company failed to give an apology to the citizens for doing so. The citizens wonder why this was not done before, as the investment of 12 million BAM ($ 8,500,000) for the filters represent a low level investment to ArcelorMittal, having in mind it is a third most profitable company in Bosnia. Even though the installation of the filter should have kept the pollution within the prescribed legal norms, on 17th of December 2013, the measuring station in Zenica have recorded 1,392 mg of SO2 in the air. According to Environmental Protection Department of the Municipality of Zenica, citizens have great impact on the elevated concentrations of SO2 in the air and they were advised to minimize burning coal for heating, and use of the family vehicle. Samir Lemeš from EJO Eko Forum has responded that citizens of Zenica burn coal as the alternative to central heating as ArcelorMittal (who provides heating for the municipality) has the highest heating costs in the region. The Municipality claims they cannot control the pollution coming from ArcelorMittal as it is in jurisdiction of the federal environmental inspection.
In 2015, NGO "Eko forum" filed a criminal charges against the company and the relevant federal authorities given the continuous high level of air pollution and the fact that their comments and suggestions in the process of ArcelorMittal environmental permit renovation were ignored. This is the first charge for environmental crimes in B&H. The plant was operating without some of the required environmental permits since December 2014, other permits expired in November 2015. In January 2016, another lawsuit was filed against the Federal ministry of Environment and Tourism of B&H, this time by the authorities of the city of Zenica.