Over the last couple of weeks, I have noticed that their seems to air in our waters pipes. It seems to happening with the cold water lines. We hear the spitting sound in the bathrooms, kitchen, washer. What would be the cause of this?

Pump or city water?

City Water.

Do you have a pressure reducing valve installed just after the water service enters your house? Since it' has affected all your cold water faucets this could be caused by small pebble that's caught up in a elbo and is causing the water to cavitate and put bubbles in the system. Another explanation could be the city working on the main. Have you checked with your neighbors to see if they have the same problem? If it's not the city then start at the first faucet that's spitting and work backwards. How about the hose bibs? Do they spit also?