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.
Nitric oxide reacts with oxygen (O2) and ozone (O3) to form nitrogen dioxide (NO2), a brown fume and an environmental pollutant. Nitric oxide generated from automobile engines, industries and power plants is the cause of acid rain and smog.