main source of air pollutants. Medellin's shift toward urbanization, has increased the number of vehicles and thus extended the use of fossil fuels. Areas known for heavy traffic are monitored by meters that measure the amount of air pollution. Some of the sectors that have been recognized with the highest levels of pollution within the metropolitan area are: Itagüí-Ditaires, Politécnico Jaime Isaza-Cadavid, and Downtown Medellín (particularly the Miguel de Aguinaga building and San Antonio Park). Downtown Medellin's pollution rates exceed the norm established by the WHO of being a risk to human health. Cali Cali is the capital of Valle del Cauca municipality, and one of the city's of greatest concern in terms of air pollution in Colombia together with Bogotá and Medellin. City authorities launched the "Clean Air for Cali Program" to reduce atmospheric contamination; the program deals with emissions and their health impacts, improving air quality monitoring, implementation of measures to reduce contamination, and the cost-benefit evaluation those measures. Air quality reports are publicly available. Water pollution Colombia is well endowed with rich water resources with a national average fresh water supply of more than 2,100 cubic kilometers. This is several times larger when compared to other Latin American countries like Argentina and Mexico. But Colombia is facing a serious problem of water pollution. This is limiting their use of abundant water resources for water supply, recreation and ecological benefits. Toxic and pathogenic pollution Rivers such as Bogotá, Cali, Combeima, Otún, Medellín, de Oro, Pamplonita, and Pasto which are one of the important water resources of Colombia are highly contaminated due to direct discharge of untreated effluents, pathogens and various other toxic substances primarily discharged by the agricultural sector, industrial sector and the mining sectors. These contaminants may result in cumulative and persistent consequences. Crude oil spills due to the acts of sabotage by leftist guerrilla squads, have become another cause of water pollution in the country. Mining sector Colombia is one of the largest producers of gold in Latin America. It has recently increased its production, especially in the Departments of Antioquia, Chocó, Bolívar and Córdoba, which in 2014 produced 90% of Colombia's gold. Most of this production comes from artisanal and Small-Scale Gold Mining (ASGM). The artisanal gold mining sector in Colombia has 200,000 miners officially producing 30 tons Au/a. The impact of gold mining on the environment mainly depends on the location of the metal