 The young, elderly, and those with lung diseases are especially susceptible.Ozone is most likely to exceed safety limits from May through October when seasonal heat and sunlight are at their highest  However, similar conditions can occur at other times of the year in specific urbanized areas; namely the Los Angeles area, which is well known for smog formation.A major cause of the conditions is due to pollutants in the air released by heavy industry (manufacturing plants, refineries, coal-fired power plants).