1.   As highways became more congested, accidents increased and pollution worsened.

2.   Pollution has worsened in recent days due to an unusual lack of rain.

3.   Quintana said pollution has worsened in recent days by a two-week lack of rain.

4.   Pollution is worsening.

5.   Acknowledging that pollution is worsening, the government has proclaimed environmental protection a national goal.

6.   Air pollution in general has worsened in Manila despite declining economic activity, and other urban areas of Asia enjoyed only a temporary respite from the economic crisis.

7.   But it had not helped much and the air pollution worsened.

8.   Air pollution worsens considerably here in winter because Mexico City is in a valley.

9.   The government has said it will close schools, colleges and declare public holidays if the pollution worsens.