TRAVIS COUNTY -- Expect to see and hear planes flying over Travis County the next few days. The Environmental Protection Agency (EPA) is conducting special air tests for chemicals and radiation.

Travis County asked the EPAto come in preparation for Formula 1 weekend. The goal is to be ready in case a terrorist leaks chemicals into the air that could cause injury or death.

They might hear and see a low-flying, fairly large plane. It's a dual propeller plane. They'll be conducting slow flights. They might hear loud noise and see the airplane, said Lisa Block with Travis County Emergency Services.

Pilots will be flying an ASPECT aircraft. It's a dual-propeller plane with US EPA written on both wings. The plane uses a scanner to collect air samples and test for chemicals, dirty bombs or improvised nuclear devices. The aircraft sends the data to emergency officials and first responders.

Today is a baseline measurement of the air quality. They'll be looking for any chemical or radiological qualities in the air, said Block Wednesday.

The aircraft is commonly used when big events come to town. This is the first time it's flown in Travis County, according to Block. The ASPECT has been used at the Superbowl, the WorldSeries, the Olympics, the Columbia shuttle recovery and for hurricane damage.

The plane is equipped with GPS and a navigation system and works with programs such as Google Earth. The craft is based out of Kansas City. It can deploy to anywhere in the United States in less than nine hours.

It is a large event; the first one. We're gonna have lots of important people here in the Austin area. It's such a high profile event, we feel it's important to keep everyone safe, said Block.

If something were to happen, if a suspicious chemical were detected, security officials would determine the threat level, decide whether an evacuation would be needed and get Homeland Security involved and follow necessary protocols.

The EPA will conduct another round of testing Nov. 16, 17 and 18. The tests will happen in the early morning hours and will be visible to the public.

Again, there's no evidence of any threat that would call for such a mission; it's just standard policy during a big event.

Click here for a list of downtown Austin road closures during Formula 1 weekend.