How are we protected from dangerous air pollution?

Grade level: 4th – 6th grades

Skills: Place value (whole numbers)

Related environmental issues: Air

Clean air is essential for our health.The United States has protected Americans from dangerous air pollution that cause asthma, lung diseases, and early death by enacting the law called the Clean Air Act. It is estimated that the Clean Air Act will save at least 230,000lives by 2020 in this country.


  1. What digit is in the tens place of 230,000?
  2. What place is the 3 in 230,000?
  3. How many thousands are in this number?
  4. How many hundreds are represented by the 2?
  5. How many ones are represented by the 3?
  6. Which number represents 230,000?
a.23  x 102
b.23 x 103
c.23 x 104
d.23 x 105


Source: U.S. EPA, Clean Air Act Overview.

Photo: WWF


Answer keys

2.Ten thousands




The 225 Math Quizzes That Will Make You An Environmental Expert (2019) is available from  (paperback)

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