The first US state that lowers speed limits for air quality reasons is Texas. This means that all roads with 70 mph (110 km/h) or 65 mph (105 km/h) speed limits be deducted by 5 mph. This was part of a plan to reduce smog-forming emissions in areas out of compliance with the federal Clean Air Act.
Lower speed limits could bring the areas roughly 1.5% closer to compliance. However, follow up studies found that the actual reduction is far less.
According to Governor Perry, this is a way of making driving a little more convenient while also ensuring we all do our part to clean the air. The EPA approved higher speed limits because Texas has demonstrated an unwavering commitment to cleaner air.
The Texas Department of Transportation also begin using cleaner diesel fuel in 75 percent of its Houston district fleet and establish rules requiring its contractors working in Southeast Texas to use cleaner-burning emulsified diesel fuel in off-road equipment.
Those actions are expected to remove 5.8 tons of nitrogen oxide, a major component of air pollution, from the air each day. That would amount to a reduction in emissions of at least 19 percent.
