Investigating Incursion of Transboundary Pollution into the Atmosphere of Dhaka, Bangladesh

Table 2

Trajectory paths and ranks in their association with high pollution at Gazipur station.

Cluster	96-hour trajectory path and direction of entering the station	Pollution association (rank)		Contribution from long range sources
		PM10 conc.	PM2.5 fraction
C1	Most of them started from the middle of India and entered the station from the west.	Very high ()	Moderate ()	Low
C2	Most of them started from Iran and the Middle East, several from north-Europe, travelled with good height, over Nepal, and entered the station from the north.	Moderate ()	Very high ()	High
C3	Started from several directions; some from the Middle East, some from India; some had long flight; some had shorter paths and entered the station from the north-west.	High ()	Moderate ()	Moderate
C4	Starting point somewhere in Afghanistan or Tajikistan; took a zigzag and entered the station from the north.	Low ()	Moderate ()	Moderate
C5	Started from the east and entered the station from the east. Shorter length.	Low ()	High ()	Moderate
C6	Marine air; started from the south and entered the station from the south.	Low ()	Low ()	Low

Compared to C1, C2, and C3, but the pollution level is still very high.