Because air pollution is caused by human activity, such as factories, power plants and automobiles. There is very little of these kinds of activity happening on the sea, since there are no roads or factories on the sea. When wind blows from the Pacific Ocean towards land, the clean air will replace the dirty air that is created on land by cars and factories. If there is a high pressure system blocking the wind from the sea, then the polluted air stays around instead of being blown to another part of the country. Air from the ocean is alos cooler than the air on land since land can heat up quickly and at night the heat will escape from the rocks and other objects to heat the air up. Water takes a lot of heat to warm up and it does not release heat as quickly either. So, land near large bodies of water tends to be cooler in summer and warmer in winter.
· 1 month ago