NOTE: High Pollution Advisory (HPA): Notifies the public that the level of an air pollutant is expected to exceed the federal health standard.Ground-level ozone pollution is harmful to lungs and can trigger asthma. Children are at the greatest risk from ozone because their lungs are still developing, they are most likely to be active outdoors and they are more likely than adults to have asthma. Adults with asthma or other lung diseases and older adults are also sensitive to ozone.
Although there are higher-risk groups, all county residents can be affected by ground-level ozone. 
Posted on: April 28, 2017
Ozone High Pollution Advisory issued for Sunday, April 30, 2017
The Arizona Department of Environmental Quality (ADEQ) is issuing an Ozone High Pollution Advisory (HPA) for Maricopa County, effective Sunday, April 30, 2017. This HPA is due to ozone levels expected to accumulate enough to exceed the federal health standard for ozone.People most affected by ozone include children, senior citizens, people who work or exercise outdoors and people with pre-existing respiratory disease. Ozone can irritate the respiratory system, aggravate asthma and reduce the immune system’s ability to fight off respiratory infections. Ozone-related health problems include shortness of breath, coughing, wheezing, headaches, nausea, and throat and lung irritation.
Ground-level ozone forms when emissions from vehicles, gasoline and diesel equipment, industrial and chemical processes and other everyday activities react to sunlight. Naturally, ozone pollution is more prevalent during the spring and summer months because these emissions – volatile organic compounds (VOCs, solvents and fuels) and nitrogen oxides (NOx) react more readily in higher temperatures.
Source: Air Now
