Cuban scientists monitoring environmental pollution said on Monday that there is "a tendency of an increase in the acid rain" in the country.

Experts from the Pollution and Atmospheric Chemistry Center (CECONT), quoted by the daily Granma, found that 25 percent of the annual rainfall levels in the country contain "light, medium and high" acidity.

Osvaldo Cuesta Santos, president of CECONT, stressed "the importance and the need" of monitoring the increase of acid rain.

Cuesta stated that these high levels of rain acidity in Cuba are due to "air masses capable of transporting pollutants for long distance far from the geographic areas where they were generated, and the increased local emissions of sulfates and nitrates.

By provinces, acid rain is more common in the mining-metallurgical north areas of Holguin, Pinares of Mayari, and Nuevitas.

Acid rains, including dew, hail, fog and snow, are those whose PH is below 5.5.

This phenomenon occurs when moisture from the air reacts with nitrogen oxide and sulfur dioxide, emitted by burning fossil fuels and other industrial activities.

By interacting with water vapor these gases form sulfuric and nitric acid, which precipitate into the Earth's surface along with other substances suspended in the atmosphere.