Sulfur dioxide (SO2) from human sources comes primarily from smelters and coal burning power plants. Hot sulfur dioxide also originates from natural sources, including volcanic emissions and sea spray. Nitrogen oxides come
primarily from automobile exhaust and other combustion processes, and some is created by lightning and soil
microbes. In past decades, to reduce air pollution in areas near power plants, utilities built tall smoke stacks to vent
emissions high up into the air, away from local communities. As these smokestacks push emissions up into the
atmosphere, the emissions react with the water particles in the air and are transported long distances by the wind.
Because the prevailing winds in the U. S. are from West to East, eastern regions are more affected by acidic
precipitation, even though the source of the emissions may be many miles away. However, nitrogen oxides from
automobile exhaust contribute to acidic precipitation in all densely populated areas with heavy traffic.

What we need to do. Identify the transitional word/s or phrase/s in the following sentences. Identify the type of transition.

Please help me to understand this thank you in advance.