How often should I change the air filter in my Ford Transit Custom?

I have a Ford Transit Custom and I was wondering how often I should change the air filter. I know it's important to keep it clean for engine performance, but I'm not sure how often is necessary. Any advice?

It's recommended to change your air filter every 12,000 to 15,000 miles, or at least once a year.

If you frequently drive in dusty or dirty conditions, it's a good idea to change the air filter more often, around every 6,000 to 8,000 miles.