1.   Given the enormous and costly pollution control efforts to tackle ozone pollution to date, these variable ten-year trends are very disappointing.

2.   In California, pines suffer from yellowish flecking due to ozone pollution and Los Angeles is notorious for its thick ozone smogs.

3.   Low-level ozone pollution is triggered by the action of sunlight on vehicle exhaust emissions, with still, sunny days providing the best conditions.

4.   A series of other steps will be triggered by particularly high levels of low-level ozone pollution.

5.   Increasing amounts of low-level ozone pollution are giving rise to an asthma epidemic among babies and young children, according to a senior government health adviser.

6.   Arizona and Maricopa County health agencies will issue alerts about ozone pollution and tips on how to prevent it.

7.   Beginning Friday, state and county health agencies will issue alerts about ozone pollution and tips on how to prevent it.

8.   But just as some asthmatics catch a break, ozone pollution hits its peak, triggering asthma attacks in those sensitive to the invisible summertime pollutant.

9.   But note that heat alone will not cause ozone pollution.