[CẬP NHẬT ĐỀ THI IELTS WRITING TASK 1 - NGÀY 7/1/2016]

The chart shows the average daily minimum and maximum levels of air pollutants in 4 big cities in 2002

The chart shows the daily minimum and maximum amount of SO2 and N2O emission in four cities, namely Los Angeles, Calcutta, Beijing and Mexico City in 2002. In general, the quantity of pollutants in Mexico City was the highest among four cities.

To be more specific, the lowest level of SO2 in Mexico City was around 80 micrograms per m³ (70 units), nearly twice as large as that of Calcutta and by far ahead those of Los Angeles and Beijing. Similarly, the maximum amount of SO2 in Mexico City was 200 units, which was much greater than the emission in Beijing, Calcutta and Los Angeles at 140 units, 55 units and 10 units, respectively.

Regarding the emission of N2O, Mexico City was even affected by N2O more seriously with the figure ranging from 110 units to 210 units every day. Holding the second position was Los Angeles, with the highest level reaching 100 units, approximately three times as high as the maximum figures for Calcutta and Beijing. Meanwhile, the lowest levels of N2O emission in Los Angeles, Calcutta and Beijing were insignificant, at below 50 units each.