Air monitoring Air pollution Pollutant types Installations for

Air monitoring. Air pollution. Pollutant types. Installations for air monitoring.

Air pollution • The presence in atmosphere of one or more contaminants in such quantities and of such duration as is or tends to be injurious to human health, animal or plant life, or property.

Air pollution – the problem • Global • Regional and urban • Local • Indoor (homes, factories, offices)

Air Pollutants Types Pollution can be grouped into two categories: (1) primary pollutants, which are emitted directly from identifiable sources, and (2) secondary pollutants, which are produced in the atmosphere when certain chemical reactions take place among primary pollutants.

Primary Pollution • The major primary pollution include: particulate matter (PM), sulfur dioxide, nitrogen oxides, volatile organic compounds (VOCs), carbon monoxide, and lead.

Secondary Pollution Atmospheric sulfuric acid is one example of a secondary pollution in urban and industrial areas is often called Air smog. Photochemical smog, a noxious mixture of gases and particles, is produced when strong sunlight triggers photochemical reactions in the atmosphere. The major component of photochemical smog is ozone.

Effects of human activities on the atmosphere (NSW SOE 2000)

Controlling Air Pollution through Regulations Regulatory efforts to control emissions include setting of standards for four of the primary pollutants— particulates, sulfur dioxide, carbon monoxide, and nitrogen well as the secondary pollutant ozone. as

Note! • when air pollution episodes take place, they are not generally the result of a drastic increase in the output of pollutants; instead, they occur because of changes in certain atmospheric conditions.

Emission sources. Typical parameters of the point source: • emission intensity (E) • geometric height of the source (h) • stack diameter at the source exit (d) • gas velocity at the source exit (v) • gas temperature (T) • stack localization in the geographical coordinate system (x, y)

Ambient air quality monitoring in urban microenvironments such as sidewalks, bus stations, parking garages, under different climate conditions - Slater Street, Ottawa

• Ambient sampling stations constructed at ETC for roadside measurement of VOC, PM 2. 5, and carbonyl compounds

Air quality monitoring Methods and instrumentation Gas measurement using spectroscopic methods Spectrophotometry is based on the interaction of the gas molecules with light. Absorbtion techniques – it is measured the intensity of light after passing through a gaseous medium. Usually absorption is measured at several frequencies in order to avoid offests and interferences with other species. There are 4 principles: • Differential Optical Absorption Spectroscopy (DOAS) • Fourier Transform Infrared (FTIR) • Non-Dispersive Infrared (NDIR) • Tunable Laser Diode Absorption Spectroscopy (TLDAS)

Air quality monitoring Measurement of nitric oxides (NOx) by chemiluminescence Chemiluminescent reaction NO + O 3 ==> NO 2+ O 2 + hv (0. 6 – 3 μm)

Air quality monitoring Measurement of sulphur dioxide (SO 2) by UV fluorescence

Air quality monitoring Measurement of suspended particles (particulate matter – PM) Fraction Size range PM 10 (thoracic fraction) ≤ 10 μm PM 2. 5 (respirable fraction) ≤ 2. 5 μm PM 2. 5 – PM 10 (coarse fraction) 2. 5 - 10 μm PM 1 (fine fraction) ≤ 1 μm Ultrafine (UFP or UP) ≤ 0. 1 μm Aerosol = particles + gas

Air quality monitoring Measurement of suspended particles (particulate matter – PM) Beta Attenuation Method