Environmental Data Definitions, and Predictive Models

PM10, PM2.5: Particulate matter

PM10, PM2.5 Particulate Matter measures are expressed in microgram for cube meter of particles of 10/2.5 micrometers or less, PM2.5 are more critical. The size of the particle is a determinant respiratory tract the particle will come to rest when inhaled. Larger particles are generally filtered in the nose, but particulate smaller than about 10 micrometers can settle in the bronchi and cause health problems. The 10-micrometer does not represent a strict boundary between respirable and non-respirable particles. Due to small size, particles on the order of 10 micrometers or less (coarse particulate matter,PM10) can penetrate the deepest part of the lungs such as the bronchioles or alveoli; when asthmatics are exposed to these conditions it can trigger bronchoconstriction. The sources can be natural (soil erosion, marine spray, volcanoes, forest fires, pollen dispersion, etc.) or anthropogenic (industries, heating, vehicular traffic and combustion processes in general). It can be of primary type if placed in the atmosphere directly from the source or secondary if it is formed subsequently, following chemical-physical transformations of other substances. It is therefore a pollutant that does not appear as a specific chemical entity but as a mixture of particles with the most varied properties. The major components of atmospheric particulate matter are sulphate, nitrate, ammonia, sodium chloride, carbon, mineral dust and it is estimated that in some urban contexts more than 50% is of secondary origin. [LINK]

NO, NO2, NOX: nitrogen oxides  

NOx  is a generic term for the nitrogen oxides that are most relevant for air pollution, produced from combustion, namely nitric oxide (NO) and nitrogen dioxide (NO2 ). These gases contribute to the formation of smog and acid rain, as well as affecting tropospheric ozone. NOx  gases are usually produced from the reaction among nitrogen and oxygen during combustion of fuels, such as hydrocarbons, in air; especially at high temperatures, such as occur in car engines. In areas of high motor vehicle traffic, such as in large cities, the nitrogen oxides emitted can be a significant source of air pollution. NOx  gases are also produced naturally by lightning. The term NOx  is chemistry shorthand for molecules containing one nitrogen and one or more oxygen atom. It is generally meant to include nitrous oxide (N2O), although nitrous oxide is a fairly inert oxide of nitrogen that has many uses as an oxidizer for rockets and car engines, an anesthetic, and a propellant for aerosol sprays and whipped cream. Nitrous oxide plays hardly any role in air pollution, although it may have a significant impact on the ozone layer, and is a significant greenhouse gas. [LINK

SO2: Sulfur dioxide

Sulfur dioxide (also sulphur dioxide in British English) is the chemical compound with the formula SO2. It is a toxic gas with a burnt match smell. It is released naturally by volcanic activity and is produced as a by-product of the burning of fossil fuels contaminated with sulfur compounds and copper extraction. [LINK]

CO: Carbon monoxide

CO is a colorless, odorless, and tasteless gas that is slightly less dense than air. It is toxic to animals that use hemoglobin as an oxygen carrier (both invertebrate and vertebrate) when encountered in concentrations above about 35 ppm, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal biological functions. In the atmosphere, it is spatially variable and short lived, having a role in the formation of ground-level ozone. [LINK]

O3: Ozone

Ozone or trioxygen, is an inorganic molecule with the chemical formula O3. It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope O2, breaking down in the lower atmosphere to O2 (dioxygen). Ozone is formed from dioxygen by the action of ultraviolet light (UV) and electrical discharges within the Earth's atmosphere. It is present in very low concentrations throughout the latter, with its highest concentration high in the ozone layer of the stratosphere, which absorbs most of the Sun's ultraviolet (UV) radiation. Ozone is a powerful oxidant (far more so than dioxygen) and has many industrial and consumer applications related to oxidation. This same high oxidising potential, however, causes ozone to damage mucous and respiratory tissues in animals, and also tissues in plants, above concentrations of about 0.1 ppm. While this makes ozone a potent respiratory hazard and pollutant near ground level, a higher concentration in the ozone layer (from two to eight ppm) is beneficial, preventing damaging UV light from reaching the Earth's surface. [LINK]

Helsinki Air Quality Index

It is an estimation of the Air Quality Index adopted in the Helsinki area and provided by FMI sensors in a scale from 1 to 5. Its meaning and mechanisms to its estimation seem to be not available. See also for other details on: Air Quality Indexes

European Air Quality Index http://airindex.eea.europa.eu/ 

The European Air Quality Index takes into account for air quality assessment about PM10, PM2.5, NO2, O3, and SO2 considering the worst cases among the values of those measures according to a formula. The resulting index from 1 to 5 (good, fair, moderate, poor and very poor) indicate the quality of air. See also for other details on: Air Quality Indexes

Enfuser Air Quality Index (predictions) 

[FINNISH METEOROLOGICAL INSTITUTE]

[FMI-ENFUSER Modelling System]

Air quality index is used to describe the air quality in simple terms and an easy-to-understand color scale. It is based on measured air quality data and gives an overall characterization of the actual air quality. Finnish air quality index is a hourly index which describes the air quality today, based on hourly values and updated every hour. The index takes into account the concentrations of sulphur dioxide (SO2), nitrogen dioxide (NO2), respirable particles (PM10), fine particles (PM2.5), ozone (O3) carbon monoxide (CO), and the total reduced sulphur compounds (TRS). The measured concentrations are compared with the current air quality guidelines. The air quality index in use in Finland is developed and maintained by the Helsinki Region Environmental Services Authority HSYand the National Institute for Health and Welfare THL. See also for other details on: Air Quality Indexes

GRAL predictions

The so called GRAL model is the Graz Lagrangian Model. The basic principle of Lagrangian models is the tracing/tracking of a multitude of fictitious particles moving on trajectories within a 3-d wind field. GRAL as described here is a sophisticated operational model. It takes into account: pollution sources (for example the vehicles, their distribution on the streets, the about of pollution they produce according to their distribution of time and space, etc.), the structure of the city (streets and shape 3D of the building), weather forecast (wind intensity and direction), etc. The aim of GRAL is computing the prediction of the distribution of particles of pollution or any other kind in the field created by the wind and city shape. The GRAL model can be applied to a number of particles as NO and NO2 (NOX), PM (10 and 2.5), etc., and computes the distributions at different heights from the ground. The estimation preformed are mainly at 3mt (when it is not specified) and 6mt when it is specified).  The predictions can be estimated 24/48 hours in advance or more and may be for every hour, for example. The computational process is computationally heavy for this reason the data are computed only in central part of cities for demonstrative purpose and for assessing the model and results in the most critical parts and conditions. The GRAL model has been validated by several research teams and in several contexts and could be considered as an in progress model/approach for environmental data prediction: [LINK]