Fill in each blank with a word from the box to complete the following passage. (1,25 pts)

Environment            diseases           pollution             emission                   upgrading

If you wander on the streets of Ha Noi, the capital of Viet Nam. you may be surprised that most people are wearing masks, hiding their faces. This is because of serious air 26.__________in this city. Between March 1 and 4, 2016, the air quality index of Ha Noi, as measured by the US Embassy in Ha Noi was over 350. At this level, air pollution can cause lots of respiratory 27.__________especially to children and the elderly. The major cause of air pollution in Ha Noi is traffic. Due to the increasing number of motorcycles and cars in the last decade, the 28.__________of chemical exhausts has been on a constant rise. Another reason is urban construction, including road 29.__________projects and residential buildings. People have to live with the dust and dirt throughout the city. Environmental experts have warned that if the city continues to develop its economy with little regard to the 30.__________ the consequence will be tragic.