NEWARK, NJ - On sunny and hot days, heat and sunlight react with hydrocarbons and nitrogen oxides emitted by internal combustion engines like automobiles, trucks and gasoline powered lawn equipment. These mix to form a ground-level layer of ozone.

The National Weather Service issued an air quality alert for Bergen, Essex, Passaic, Union and Hudson counties in New Jersey until 11 p.m. July 10. According to he alert, the New Jersey Department of Environmental Protection 'An Ozone Action Day' has been declared.

Ozone is forecast to reach the unhealthy for sensitive groups category along the I-95 corridor with the opportunity for areas in northern New Jersey to reach the unhealthy category due persistent sunshine, warm temperatures, and light winds.

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Sensitive individuals including the very young, the elderly, and persons with respiratory diseases such as asthma, should avoid strenuous outdoor activities during the afternoon and early evening hours.

When inhaled, even at very low levels, ozone can cause acute respiratory problems, aggravate asthma, result in a 14-20 percent decrease in lung capacity for healthy adults, cause inflammation of lung tissue, lead to increased hospital admissions and emergency room visits and impair the body’s immune system defenses, making more people susceptible to respiratory illnesses such as bronchitis and pneumonia.