What causes rain water to ended up with 1.3 pH?

Rainwater typically has a pH of around 5.6 due to the presence of carbon dioxide in the atmosphere, which forms carbonic acid when it reacts with water. However, rainwater can become more acidic (lower pH) due to air pollution.

Acid rain is caused by emissions of sulfur dioxide and nitrogen oxides from industrial activities, vehicles, and power plants. These pollutants can react with water in the atmosphere to form sulfuric acid and nitric acid, which can lower the pH of rainwater to as low as 1.3 in extreme cases.

Therefore, the main cause of rainwater ending up with a pH of 1.3 is the presence of high levels of sulfuric acid and nitric acid in the atmosphere, resulting from air pollution.

Rainwater is naturally acidic with a pH of around 5.6 because it absorbs carbon dioxide from the atmosphere, forming carbonic acid. However, in areas with high levels of pollution, rainwater can become even more acidic, sometimes with a pH as low as 1.3. This is caused by the absorption of sulfur dioxide and nitrogen oxides from the air, which form sulfuric acid and nitric acid, respectively. These acids can cause damage to buildings, soil, and plants, and can also be harmful to human health.