A-Over time, even with good teeth cleaning, plaque and tartar can attach to the teeth similar to lime build-up in a kettle or iron. The saliva fluids in our mouths contain calcium and bacteria.-According to oral hygiene standards, it is recommended that patients visit the dentist every six months for an oral health check-up, to discuss any medical changes such as new medications that can affect oral wellbeing, and to have teeth cleaned with scaling and polishing where necessary.
Industrial smog occurs when the smoke and sulfur dioxide produced from burning coal merges with fog and creates a yellowish-brown-colored haze close to ground level. Photoch â¦ emical smog forms as the result of increased usage of all fossil fuels, including gasoline and the burning of trees and organic waste.
On the other hand, carbon monoxide is the result of incomplete combustion in the carâs engine which in turn can cause high levels of oxygen. Common Reasons. There are certain causes of gas related smog check failures for each of these gases. Common causes of high levels of NOx or Nitrogen Oxides include advance timing and a faulty EGR system. The EGR System or Exhaust Gas Recirculation System is the main component in the exhaust gas recirculation system.