Non-methane volatile organic compounds (NMVOCs) are a large variety of chemically different compounds, such as benzene, ethanol, formaldehyde, cyclohexane, 1,1,1-trichloroethane or acetone. Essentially, NMVOCs are identical to volatile organic compounds (VOCs), but with methane excluded. Methane is excluded in air-pollution contexts because it is not harmful. Its low reactivity and thus long livetime in the atmosphere, however, makes it an important greenhouse gas. They can cause a dense ozone close to the ground and they are a serious air pollutant and long exposure t them can cause damages to the functioning of lungs, they can damage the liver, kidneys and central nervous system. Some of them are known carcinogens.
Express the severity of a meteorological condition for a given area and in a specific time period. HDDs are defined relative to the outdoor temperature and to what is considered as comfortable room temperature. The colder is the weather, the higher is the number of HDDs. These quantitative indices are designed to reflect the demand for energy needed to heat a building
