Check your owner’s manual for the manufacturer’s recommended intervals. But depending upon where and how you drive, a good rule of thumb is every 12 months or 12,000 miles. As air filters get clogged with dirt, grime, and debris, the volume of take air is restricted, decreasing performance and engine power.
If ignored long enough, a contaminated air filter can cause your engine to work harder negatively impacting both efficiency and economy. There’s little safety risk, just decreased power and performance, but neglecting your air filter can have a big impact on the environment.