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Michigan to monitor smog in eight counties amid switch to summer gasoline

A tanker truck driver delivers gasoline to a gas station
Gas retailers nationwide have until Saturday to switch to summer-grade fuel. The blend contains less butane but may cost drivers more at the pump. (Shutterstock)
  • Gas stations have until Saturday to switch to summer-grade gasoline, which contains less butane and causes less pollution
  • In line with the switch, Michigan agriculture officials plan to monitor smog levels in eight counties 
  • The average gas price in Michigan is $3.58, down from Memorial Day

Saturday is the last day for gasoline retailers to make the annual changeover to cleaner-burning, summer-grade fuel. Meanwhile, state agriculture officials have announced plans to monitor ozone levels in eight counties “as an extra measure” to reduce smog.

The Clean Air Act gives the Environmental Protection Agency the authority to require states to switch over to summer-grade gas.


Summer-grade gasoline typically contains 2% butane, a colorless, odorless gas that is used in lighter fluid, for example, according to AAA. In the winter, gasoline contains more butane, to help vehicles start up in colder weather.  


The summer blend burns cleaner and contributes less to air pollution, which is more of a threat in hot weather. 

“Summer formula gasoline increases fuel efficiency and helps prevent smog-causing compounds from being released into the atmosphere,” said Craig VanBuren, director for the Laboratory and Consumer Protection Bureau for the Michigan Department of Agriculture and Rural Development. “MDARD inspectors will conduct on-site testing during the summer gas season, which runs from June 1 to September 15.”  

Fuel terminals were required to make the switch by May 1, according to the Energy Information Administration but gas stations have until Saturday to make the switch to summer-grade gasoline. 

Gas stations in several counties in southeast Michigan will be monitored by MDARD beginning Saturday when gas stations are required to only sell the summer grade-fuel, to ensure that the smog levels remain low. 

"Gov. Whitmer has taken bold actions to protect Michigan's environment, which we echo at MDARD," said director Tim Boring in a statement. "Our department is committed to protecting Michigan's environment as our industry continues to implement climate-smart practices focused on combating climate change in Michigan."

The EPA regulates the “Reid Vapor Pressure,” or RVP, of gasoline sold at retail stations during the summer. RVP measures the volatility of gasoline. The higher the RVP, the faster it will evaporate and contribute to ground-level ozone. Enforcement of a low-RVP requirement means that the state will continue receiving federal highway funding.  

To ensure low smog levels, MDARD will monitor the ozone levels in Lenawee, Livingston, Macomb, Monroe, Oakland, St. Clair, Washtenaw, and Wayne counties.

Gas retailers in these counties must only sell or dispense gas that does not exceed 7.0 pounds per square inch vapor pressure, according to the department. 

Summer-grade fuel is more expensive to produce and people tend to drive more as the weather warms, increasing demand — yet another factor in higher summer prices.


Post-holiday price drop

Last week the average price for a gallon of regular gas in Michigan was $3.69, just as many residents hit the road for Memorial Day travel. This week the average is $3.58, according to AAA Michigan.  

AAA listed the average per-gallon price for regular gas in select Michigan metropolitan areas:

  • Ann Arbor:  $3.63 
  • Benton Harbor: $3.55 
  • Flint: $3.56 
  • Grand Rapids/Muskegon/Holland: $3.60 
  • Jackson: $3.66  
  • Lansing/East Lansing: $3.62
  • Marquette: $3.57 
  • Metro Detroit: $3.58
  • Saginaw/Bay City/Midland: $3.59
  • Traverse City: $3.55

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