People don’t often tell you about how many statistics reports have variances. Those numbers in the news articles, or even on your medicine bottle, often have a point of reference that doesn’t work for everyone. As an example, I take a standard fish oil pill every day. I do this, as I have high blood pressure and don’t get enough healthy fat in my diet. My brother, on the other hand, takes a super-dose of cod liver, krill and salmon oil in a pill once a week. Though my bottle says ‘do not exceed standard dose, unless directed by a doctor’, he does exactly that. Well, the same can be said of your car and your Heating, Ventilation, and A/C system! If you put your car through a lot of work and regularly dog the engine and transmission, you’ll need to change the oil more often and bring it in for a tune up every now and again. If you have a lot of pets or keep a fairly dirty home, you’ll need to change your air filter for your heating, ventilation and air conditioning system more often. Most HVAC repair company websites will tell you that you need to change your air filter at least once a month on average–on average being the keyphrase here! The average does not apply to most people. I change our air filter once every other month, as I have 1 cat. I also vacuum and dust often. My brother has four dogs, and a tiny apartment for one. He lives with plenty of yard space for the pets to run around in, but the small apartment and four dogs means a lot of pet hair! My brother changes her air filter often, usually at least once a month.