New Jersey has already experienced several days of poor air quality alerts even though the summer has only just begun.

The Garden State has a long history of poor air quality, but recently ground-level Ozone alert days have increased.

The American Lung Association gave nine counties in the state failing grades for Ozone days.

Ozone is helpful in the upper atmosphere. But on hot days it can develop closer to the ground. Cars, power plants and diesel vehicles can contribute to the poor air quality.

Experts say that the bad air can be worse in the afternoon and evenings. Sunlight reacts with the chemicals in the air, making it potentially dangerous to be outdoors – especially for sensitive groups like people who have asthma.

Rutgers professor Monic Mazurek says that there is some positive news. Innovations like electric vehicles are helping to improve the overall air quality around the country.

New Jersey does have reduced soot in the air compared to other places. Soot is caused by coal-fired power plants and diesel vehicles – both of which there are less of in the state.