AQI and what it all means

With the beginning of May comes not only the first hint of summer, but also the St. Louis Regional Clean Air Partnership’s (SLRCAP) air quality index (AQI). But, what does this actually mean for motorists?

The AQI converts measured pollutant concentration in a community’s air to a number on a scale of 0 to 500. In St. Louis those numbers are converted into colored days.

Green signifies a good day for air quality. Usually cool summer temperatures and either wind or clouds are associated with this day.

As the summer gets hotter and the days get longer the air quality decreases. A yellow day means moderate air quality. Temperatures range from the mid 70s and up and are accompanied by light winds and sunny skies. Days that land in the orange and red are much more apparent to the naked eye. These days are usually extremely hot and hazy. As a motorist if you see heat waves reflecting off of the pavement you know that the AQI is high. 

In the month of May last year the AQI only reached yellow five times. This year the index marked at yellow by the fourth of the month.

Air Quality Facts

The ozone is created when heat and sunlight react with hydrocarbons and nitrogen oxides emitted from automobiles, body shops, gas stations, organic solvents and various other sources. When these elements are mixed together they form the ground level layer of ozone known as smog. One thing to note is that good and bad ozone are chemically identical but it is their location in the atmosphere that creates the difference.

Transportation and Ozone Facts

• In 2009, 81 percent of Missouri residents drove to work alone on a daily basis
• The average travel time to work in Missouri was 23.2 minutes in 2009
• In 2010, over 1.3 million St. Louis residents drove to and from work during peak travel time
• St. Louis makes 7.2 million vehicle trips per day with 5.3 million of those being single person trips
• In 2008, St. Louis residents drove over 71 miles per day
• In 2010, St. Louis motorists spent an individual average of 30 hours in traffic, costing peak commuters $642 annually, and wasting 14 gallons of fuel
• One person utilizing van/carpool services can save 225 pounds of harmful emissions per year
  • This can equate to about $3,500 per year
• One highway lane can accommodate 2,250 people per hour in cars and 9,000 people per hour in buses
• Two metro tracks have the same capacity as 16 lanes of highway
  • A full MetroBus can remove 40 cars and a full MetroLink can remove 125 cars from the highways

Tips to Keep our AQI Green

• Keep your tires properly inflated. When all four tires are under-inflated by 10 percent, gas mileage will decrease by 10 percent.
• Refuel your cars and trucks after dusk.
• Choose pump sprays over aerosol. Use cooking oil over cooking spray; shaving soap over shaving cream; and, setting lotion or gel over hairspray.
• Store gasoline in dark, cool places. This preserves the gasoline so that you may use it after a prolonged period of time and keeps the fumes from evaporating into the air.
• Don’t overfill your gas tank. If you do overfill you prevent your emissions system from operating correctly.
• Mow your lawn after 7 p.m.
• When barbequing use a charcoal chimney or electric starter instead of charcoal lighter fluid.
•  Idling for 30+ seconds can consume ½ to one gallon of gas per year. This causes engine components to wear prematurely which may mean more money in the long term.
• Consider purchasing gas at stations with vapor recovery nozzles.
• Reduce the use of your air conditioning at low speed. When driving over 40 mph your air conditioning costs less fuel than having the windows open.
• Avoid roof racks and remove them when not in use.
• Replace the air and fuel filters regularly. Air filters can be purchased at a local auto parts store and changed easily.

- St. Louis Regional Clean Air Partnership

For more information on air quality please visit the St. Louis Regional Clean Air Partnerships website at http://www.cleanair-stlouis.com/

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