DAYTON, Ohio -- The Dayton and Springfield metro areas were under a Air Pollution Advisory Thursday, which means that it can be harder to breathe if you are outside.

Sunshine, warm temperatures and low humitidy are three key ingredients for ozone formation. Ground-level ozone (smog) is formed when bright sunlight mixes with emissions from vehicles and small gasoline-powered engines. These emissions collect in a stagnant air mass and form high levels of ozone.

Conditions allowed levels to rise Thursday, and as the Miami Valley sits under a stagnant air mass RAPCA issued another advisory for Friday. Sunshine and even warmer temperatures will further increase already elevated ozone levels.

It’s important that everyone takes action to reduce ground-level ozone especially on days when these notices are issued. Residents are encouraged to follow these actions:

AVOID DRIVING IF POSSIBLE Carpool/vanpool or take the bus. Vehicle emissions cause almost 50% of ground-level ozone. For short trips, walk or ride a bike.

REFUEL YOUR VEHICLE ONLY AFTER 6:00 P.M., OR IF POSSIBLE, DON’T REFUEL AT ALL WHEN AIR POLLUTION ADVISORY NOTICES HAVE BEEN ISSUED Vapors from gasoline contribute to the smog problem. By refueling after 6:00 p.m. when it’s cooler, smog doesn’t form as easily. Make sure your gas cap fits tightly so gas fumes don’t escape and contribute to the smog problem.

IF YOU MUST DRIVE, try to combine running errands or delay them until the Air Pollution Advisory notice is lifted.

DRIVE A CAR THAT IS WELL-TUNED Avoid “jackrabbit” acceleration and excessive idling, especially at drive-thru windows. If you have to wait for 2 minutes or more, it’s better to turn off the engine and go inside.

AROUND THE HOME, limit your use of small gasoline-powered equipment such as lawn mowers, chainsaws, power trimmers and shredders. Operating a gasoline-powered lawn mower for one (1) hour produces the same amount of pollution as driving a car for eleven (11) hours! Try a “push” or battery-powered lawn mower instead.

MOW YOUR LAWN AFTER 6:00 P.M. when the sunlight is not as strong and smog is less likely to form.

What is particle pollution and how does it affect me?
Particle pollution consists of the solid particles and liquid droplets found in the air. Individually, these particles/droplets are invisible to the naked eye, but collectively, they can appear as clouds or a fog-like haze. This tiny matter, less than 2.5 microns in diameter, is also known as PM 2.5, and can get deep into people's lungs. Particle pollution comes from many different sources including wood burning, diesel and gasoline-powered engines, factories and power plants. When inhaled, particle pollution can damage lung tissue, aggravate asthma, bronchitis and heart diseases - even cause premature death.

What are "Air Pollution Advisory" notices
The Regional Air Pollution Control Agency (RAPCA) monitors the air in the Miami Valley. If and when air pollution levels are forecasted to be high, an "Air Pollution Advisory" will be issued by the Miami Valley Regional Planning Commission (MVRPC) in conjunction with RAPCA.

When will these "Air Pollution Advisory" notices be issued?
These notices will be issued by 3:30 p.m. the day before air pollution levels are forecasted to be elevated. Remember also, unlike ground-level ozone, particle pollution does not need sunlight to form and can reach unhealthly levels at any time during the year. Consider this - colder temperatures result in more wood burning which increases particle pollution. Particle pollution is so fine that it can remain suspended in the air for long periods of time. Therefore, an "Air Pollution Advisory" may be issued at any time during the year.