Stanislaus County residents continue to breathe some of the worst air in the nation, according to the American Lung Association's State of the Air 2018 report.

The Modesto-Merced region made the top 10 list for worst air quality in the nation in all three categories: ozone, short-term pollution and year-round pollution.

Stanislaus County had 32 unhealthy air days because of ozone pollution (two more than last year) and 19 due to particle pollution and as such earned an F grade from the American Lung Association. The Modesto-Merced area ranked seventh in the nation for ozone pollution (Modesto-Merced was ranked sixth in 2017) and fifth for year-round particle pollution.

It's not just the Modesto-Merced area that is falling short in air quality, according to the report, all eight counties in the San Joaquin Valley received failing grades.

This year's report reveals that the ozone levels rose due to some of the warmest temperatures on record in 2016.

"Federal and state policies like the Clean Air Act and strong California clean car standards are working. We are improving air quality, but the impacts of climate change are interfering with progress," said Bonnie Holmes-Gen, senior director, Air Quality and Climate Change, American Lung Association in California. "The reality is California still has unhealthy levels of air pollution in large areas of the state, which puts Californians at risk for premature death and other serious health effects such as asthma, COPD and lung cancer. We must continue the life-saving work of cutting air pollution and slowing climate change."

The State of the Air 2018 found that 90 percent of Californians live in areas with unhealthy air at some point during the year. California's most populous metro area, Los Angeles, led the nation for ozone pollution, faring worse than it did in the 2017 report. The San Francisco Bay Area, Sacramento and San Diego also made the top 10 lists.

The State of the Air 2018 report is based on air quality monitoring data collected in 2014 - 2016, the most recent years of quality assured data available. It is important to note that the historic wildfires of 2017 were not captured in this year's report. The report focuses on ozone and particle pollution, as they are the most widespread forms of air pollution threatening public health.

"Ozone and particle pollution are especially harmful to children, seniors and those with asthma and other lung diseases. When they breathe polluted air, too often they end up in the doctor's office, the hospital or the emergency room," said Dr. Alex Sherriffs, a Fresno area physician and member of the San Joaquin Valley Air District Board and the California Air Resources Board.

"It is critical that California continues to lead the nation in the transition away from polluting fossil fuels, especially as the federal government takes steps to roll back lifesaving measures that reduce climate pollution like clean car standards," Holmes-Gen said. "Moving to a zero-emission vehicle future will have huge positive impacts on public health and improve the lives of those living with lung disease."

Learn more about California's grades including local air quality data for each county and metropolitan area at www.stateoftheair.org/california2018.