Final answer:
Yes, volcanic gases can accumulate in hollows near volcanoes, which can be very dangerous. These natural emissions have played a crucial role in the formation and evolution of Earth's atmosphere, though human activities now significantly impact greenhouse gas levels.
Step-by-step explanation:
It is true that volcanic gases can accumulate in depressions or hollows near volcanoes, creating dangerous pockets of air. These gases, such as carbon dioxide (CO₂), water vapor (H₂O), and sulfur dioxide (SO₂), can pose significant hazards. An example of this danger was the tragic event in 1986, where over 1700 people were killed in Cameroon due to a cloud of gas, likely carbon dioxide, released from Lake Nyos - a lake in a volcanic crater. Volcanic gas emissions have been a part of Earth's geological processes for eons, contributing to the formation of the planet's early atmosphere and continuing to impact it through the recycling of gases via plate tectonics.
While volcanic eruptions release substantial amounts of greenhouse gases and other pollutants, it should be noted that human activities such as large-scale deforestation and the burning of fossil fuels have become the primary sources of increased greenhouse gases in the atmosphere today, significantly contributing to climate change. Nonetheless, volcanic gases and particles can influence Earth's climate by cooling the surface for short periods following a significant eruption.