Introduction to Environmental Engineering Dr. Kagan ERYURUK

Air Pollution

Composition of Standard Dry Air

Prefixes used in naming compounds Example: CO2 = carbon dioxide CO = carbon monoxide

Converting between ppm and % 1 % = 1 particle per 100 particles = 10 particles per 100 particles = 100 particles per 10 000 particles = 1000 particles per 100 000 particles = 10 000 particles per 1 000 000 particles 1% = 10 000 ppm 1 million! Example: What is 0.007 % in ppm? 0.007 % x 10,000 ppm = 70 ppm 1 % 0.007 % = 70 ppm

What is air pollution? Air pollution consists of gases, liquids, or solids present in the atmosphere in high enough levels to harm humans, other organisms, or materials

Sources of Outside Air Pollution Combustion of gasoline and other hydrocarbon fuels in cars, trucks, and airplanes Burning of fossil fuels (oil, coal, and dinosaur bones) Insecticides Herbicides Everyday radioactive fallouts Dust from fertilizers Mining operations Livestock feedlots

Classification of Air Pollutants Classic Air Pollutants: Gaseous: SO2, CO, O3, HC, NO, NO2 Particulate: Dust, Fume Mist, Smoke, Spray Other Types of Air Pollutants: Fog Radioactivity Excess Radiation (U.V., Visible, etc.)

Primary vs. Secondary Air Pollutants Primary air pollutants: Harmful chemicals that enter directly into the atmosphere Carbon oxides Nitrogen oxides Sulfur dioxide Particulate matter Hydrocarbons Secondary air pollutants: (produced by chemical reactions in atmosphere) Harmful chemicals that are produced from chemical reactions involving primary air pollutants Ozone Sulfur trioxide

Sources of Primary Air Pollutants

Particles Particles are typically classified by their size (mass median aerodynamic diameter). In air pollution terminology, fine particles are 2.5 μm in diameter or smaller (≤2.5 μm) (PM2.5). Coarse particles are between 2.5-10 μm (PM10) in diameter. Ultrafine particles, generally considered <0.1 μm, is a subset of fine particles.

Metallurgical dust and fumes Ultrafine Particles Fine Large Sea salt nuclei Carbon black Pollens Cement dust Oil smoke Combustion nuclei Metallurgical dust and fumes Photochemical smog Insecticide dusts Coal dust Average particle diameter (micrometers or microns) 0.001 0.01 2.5 10.0 100.0 Tobacco smoke Paint pigments Fly ash Milled flour

VOCs (Volatile Organic Compounds) In rural areas, natural sources dominate. In urban areas, transportation dominates. The major anthropogenic sources of VOCs include; Solvent Use (including paints, adhesives, aerosols, metal cleaning and printing) Road transport (emissions from fuel / petroleum use) Production processes Extraction and distribution of fossil fuels Natural Sources of Volatile Organic Compounds; Plants synthesize many organic molecules and release some VOCs (including a range of terpenes) into the atmosphere

Sulfur dioxide (SO2) Sulfur is contained within all fossil fuels, and is released in the form of sulfur dioxide (SO2) during fossil fuel combustion. Fossil fuel combustion accounts for almost all anthropogenic (human-caused) sulfur emissions.  Natural occurances like volcanoes also emit sulfur dioxide. A colorless gas with a pungent, suffocating odor. A dangerous air pollutant because it is corrosive to organic materials and it irritates the eyes, nose and lungs.

Nitrogen oxides (NOx) Two main nitrogen oxides (NOx): Nitric oxide (NO) and nitrogen dioxide (NO2). Nitric oxide (NO) and nitrogen dioxide (NO2) are gaseous products of combustion from both stationary sources (e.g., power plants) and from motor vehicles. When inhaled, nitrogen dioxide becomes a serious air pollutant which may: Cause pulmonary edema (accumulation of excessive fluid in the lungs) Be part of acid rain (destroying fish and plant life in lakes, damaging surfaces of buildings etc) Contribute to photochemical smog.

Ozone (O3) Ozone (O3) is a colorless, poisonous gas with a sharp, cold, irritating odor. The natural stratospheric ozone is considered to be of beneficial nature – it keeps harmful excessive ultraviolet sunlight from reaching the surface of the Earth. As a result of anthropogenic emissions of primary pollutants, has negative effects on humans and the natural environment. Effects of Ozone as an Air Pollutant; Irritation of the respiratory system Inflammation and damage to the lining of the lungs Aggravation of asthma Reduction in agricultural yields

Altitude (kilometers) Ozone concentration (ppm) Altitude (miles) Stratospheric ozone Stratosphere Troposphere 40 35 30 25 20 15 10 5 Photochemical ozone Air

Ozone Depletion Several pollutants attack the ozone layer. Chief among them is the class of chemicals, chloro-fluoro-carbons (CFCs). CFCs are used as refrigerants (notably in air conditioners), as agents in some manufacturing processes, and formerly as propellants in spray cans.

Ozone Depletion In the stratosphere, intense UV radiation breaks the CFC molecules apart, releasing the chlorine atoms. These chlorine atoms then react with ozone (O3), breaking O3 down into ordinary oxygen molecules (O2).

5.2 Layers of the Atmosphere The atmosphere has four layers: Thermosphere Mesosphere Stratosphere Troposphere

Layers of the Atmosphere The four layers of the atmosphere include: the troposphere, where we live; the stratosphere, which contains the ozone layer; the mesosphere, where meteors burn; and the thermosphere, where satellites orbit Earth.

Indoor Air Pollution Indoor Air pollution May have higher levels of air pollutants than outdoor air. Include; radon, cigarette smoke, carbon monoxide, nitrogen dioxide, formaldehyde, pesticides, cleaning products, ozone, asbestos, allergens, and pathogens

Radon Radon is a colorless, tasteless radioactive gas produced naturally by uranium decay in the Earth’s crust. Breathing low levels of radon can lead to lung cancer Radon is the most serious indoor air pollutant

Asbestos A mineral fiber that has been used in construction materials for insulation and as a fire-retardant Most commonly found in older homes Exposure to asbestos can lead to long-term risk of chest and abdominal cancers and lung diseases

Air pollution affects human lungs, like these of this non-smoker

Temperature Inversion If the there is a temperature inversion (a warm layer above the cool surface layer), the air will not rise. This may lead to a severe pollution episode. Temperature inversions are frequently caused by radiative cooling of the ground at night.

Thermal Inversions Cities near mountain ranges When a warm front follows a cold front Result: intense local smog