Air Pollution: Sources and Health Effects Flashcards
T or F: Air pollution is the contamination of the indoor or outdoor environment by any chemical, physical or biological agent that modifies the natural characteristics of the atmosphere
true
[Other definitions of air pollution]
The presence of contaminants or pollutant substances in
the air that interfere with human health or welfare, or
produce other harmful environmental effects.
(Even the normal constituents, when found in excess
amounts, can be considered as air pollution)
The presence of contaminants or pollutant substances in
the air that interfere with human health or welfare, or
produce other harmful environmental effects.
(Even the normal constituents, when found in excess
amounts, can be considered as air pollution)
[Other definitions of air pollution]
Any alteration of the physical, chemical and biological
properties of the atmospheric air, or any discharge thereto of any liquid, gaseous or solid substances that will or is likely to create or to render the air resources of the country harmful, detrimental or injurious to public health, safety or welfare or which will adversely affect their utilization for domestic, commercial, industrial, agricultural, recreational or other legitimate purposes. (Philippine Clean Air Act of 1999)
Any matter found in the atmosphere other than oxygen,
nitrogen, water vapor, carbon dioxide and the inert gases
in their natural or normal concentrations, that is detrimental to health or the environment, which includes but not limited to smoke, dust, soot, cinders, fly ash, solid particles of any kind, gases, fumes, chemical mists, steam and radioactive substances.
What are the events that transpired in the London Smog of December 1952
dense cloud cover blocked solar radiation which caused the temperature to drop rapidly increasing the demand for home heating via coal in furnace which released ash, sulfor oxides and soot causing death from pollution due to small acid droplets easily drawing into lungs
What happened in December 2015 in China?
smog causing red alert for pollution in Beijing; air quality index = 250 (very unhealthy; visibility reduced; happened during winter months (increase in coal fire power plants)
Air Quality Index
Good 0-50 Moderate 51-100 Unhealthy for sensitive groups 101-150 (PH) Unhealthy 151-200 Very Unhealthy 201-300 Hazardous >300
amount of air a person inhales
30 m3 per day (6x more than food and drink consumed)
T or F: exposure to air pollutants is continuous and involuntary
true (why everyone is affected)
most chronic illness in children
asthma (primarily due to dust, dander etc)
The level at which one encounters any substance and is a function of intensity/concentration, frequency (how often the dose is received) and duration (how rapidly the dose is received)
Exposure
Formula for exposure
𝑬𝒙𝒑𝒐𝒔𝒖𝒓𝒆 = 𝑰𝒏𝒕𝒆𝒏𝒔𝒊𝒕𝒚 𝒙 𝑭𝒓𝒆𝒒𝒖𝒆𝒏𝒄𝒚 𝒙 𝑫𝒖𝒓𝒂𝒕𝒊𝒐𝒏
= ℎ𝑜𝑤 𝑚𝑢𝑐ℎ 𝑥 ℎ𝑜𝑤 𝑜𝑓𝑡𝑒𝑛 𝑥 ℎ𝑜𝑤 𝑙𝑜𝑛𝑔
actual amount deposited in the target; different from one person to the other; not the same as exposure
Dose
composition of earth’s atmosphere
- 9%- nitrogen, oxygen and trace levels of carbon dioxide (naturally occurring)
- 001% reactive trace gases (He, Ne, Ar, Kr, Xe)(disequilibrium mixture of chemical species)
Only mechanisms which can account for O2 abundance in the atmosphere
Photosynthesis
Regions of the atmosphere
Troposphere (closest to earth; traps air pollutants; ozone is present)
Stratosphere (ozone layer; influenced by temperature and radiation; filtering layer)
Mesosphere (air is very cool)
Thermosphere (not significant)
T or F: Natural emissions of air pollutants exceed human-produced emissions
TRUE (particulates- 85%, sulfur oxides- 50%, Carbon monoxide 9%)
Examples of natural sources of air pollution
→ Volcanic eruptions release sulfur dioxide into the atmosphere
→ Hydrogen sulfide from biological decay in marshes
→ Emission of particles from wildfires, forest fires and windstorms
− Incomplete combustion releases carbon monoxide
→ Dust storms (mixture of soil, sand, and other debris)
→ Potassium chloride from oceans
Examples of stationary anthropogenic sources of air pollution
→ Point sources – coal-fired power plant smokestacks; easier to control (sulfur dioxide) → Fugitive sources – dirt roads, surface mines, open areas where wind can easily carry dust
→ Area sources – areas of intense industrialization (produce CO2 and greenhouse gases)”
What are mobile anthropogenic sources?
Emissions primarily include nitrogen dioxides and sulfur dioxides but also include primary pollutants
T or F: Man mainly produces nitrogen dioxide
TRUE
these are pollutants emitted directly into the air such as particulates, sulfur dioxide, carbon monoxide, nitrogen oxides
Primary pollutants
These are products of reactions between primary pollutants and normal atmospheric compounds such as tropospheric zone (NO2 + VOCs) - highly reactive
Secondary pollutants
the sources of these pollutants may be limited and industry specific. They are more toxic and carcinogenic than criteria air pollutants
Hazardous Air Pollutants (188 chemicals ie benzene, formaldehyde (in woodworks), cadmium, vinyl chloride (PVC pipes)
ubiquitous air pollutants emitted from mobile and stationary sources (diverse) which poses greatest threat to human health; not very toxic but responsible for air pollution problems; with specific limits set
Criteria Air pollutants (based on clean air act of 1999)
examples of criteria air pollutants
- Suspended particulate matter – TSP and Particulate Matter 10 (meaning, 10 microns)
- Sulfur Dioxide
- Nitrogen Dioxide
- Photochemical Oxidants - Ozone
- Carbon Monoxide
An accumulation of air pollutants causes this
inversion layer (different from normal pattern where ground level air is warmer and air becomes cooler as one rises; dispersing pollution)
specific causes of inversion layer (pollution is trapped close to ground)
temperature fluctuations and radiation
Primary pollutant and contributes to acid deposition
Sulfur dioxide
Sulfur dioxide can be converted to
fine particulate sulfate because of secondary atmospheric reactions
Sources of sulfur dioxide
→ Combustion of coal and diesel fuels (major)
→ Burning of fossil fuels
→ Industrial processes such as petroleum refining
→ Production of paper, cement, aluminum
→ Burning of fuel containing sulfur (e.g. coal)
Nitrogen oxides exists manly as
nitric oxide/nitrogen monoxide (NO) and nitrogen dioxide (NO2)
T or F: nitrogen oxides also contributes to acid deposition
TRUE
This is converted from nitrogen dioxide which is a major contributor to acid rain
NO32-
What can nitrogen dioxide do?
lead to the formation of ozone, other secondary pollutants, and particulate matter
Sources of nitrogen oxides
→ Motor vehicle emissions (major) → Production by industry and traffic → Biomass burning → Microbiological emission by soil → Exchange with the stratosphere → Lighting → Air traffic
A greenhouse gas from natural microbiological processes
Nitrous oxide (N2O) *residence time = 150 years; contributes to formation of nitrogen dioxide
Length of time an air pollutant stays at a sink (e.g. forest) keeping it away from human contact
Residence time
Nitrous oxide is inert at lower atmosphere but destroyed where by how?
stratosphere by photolysis
Colorless, odorless gas which is highly toxic to humans
Carbon monoxide
How is carbon monoxide formed?
partial oxidation of carbon-containing compounds
T or F: 90% of carbon monoxide comes from anthropogenic sources such as incomplete combustion of fossil fuels, automobile emissions)
False, 10%
90% of carbon monoxide comes from natural sources such as
volcanic fires and forest fires
Other sources of carbon monoxide
Can also come from the photochemical conversion of atmospheric CH4 and other hydrocarbons
- Mixture of solid particles and liquid droplets found in the air
- Can vary widely in size and composition
Particulate matter
particulate matter which is a major contributor to aerosol loading
soil dust
Particulate matters which constitute respirable particulates found in dust with diameter smaller than 10 μm
Particulate matter 10 (coarse fraction) and 2.5 (fine fraction)
Coarse fraction consists mainly of
organic material, silicates and larget soot aggreagates (size: 2.5-10 microns)
Fine fraction ususally results from
combustion processes; secondary particulates from chemical reactions in the atmosphere such as acid condensate and sulfates (size <2.5 microns)
T or F: coarse fraction are too small to be filtered by surgical masks
false, fine fraction
*can penetrate deeply into lungs up to alveoli, the finer the particle the more toxic
What determines toxicity of a particle?
size (smaller = greater toxicity; larger Surface area for adsorption and accumulation of metals)
Fine fraction which can serve as carriers of pathogenic microorganisms, which results in an increase in the incidence of respiratory nosocomial infections
Aerosols
Some common types of particulate matter
Dust Fumes Mist Smoke, soot, ash Ozone
These are suspension of solid particles in the air generated by process such as grinding, drilling and crushing operations which are classfieid into total and respirable
dust (total: all; respirable: fraction wc passes through <7 microns selector penetratign deep into lungs)
What are fumes?
very small, volatilized solids that condense when in contact with air
Where do fumes come from?
when hot vapor reacts with air to form an oxide
Fumes are usually associated with
molten metals (welding operations and soldering operations)
Component of solder wires or solder paste which is associated with fumes
lead (solder alloy = tin + lead)
It is the dispersion of liquid particles in the air which are formed when vapor condenses back to liquid
Mist
Mist is usually associated with
acids, chlorine, formaldehyde, phenols,
Hydrogen bubbles that form in the plating tanks burst when they reach the surface, causing small droplets of electrolyte solution, which contains Cr(VI), to go into the air
Electroplating
Solid particles, mostly carbon, from combustion
Smoke, soot (very fine black powder from emissions of cars wc can deposit on walls of open areas and plants in middle of road), ash (from smoking)
T or F: Ozone is only capable of short-range transport
False, long-range (size - 2.5 microns; highest during noon)
What are the factors affecting formation of ozone?
Topography (basin like - higher o3) Temperature (higher = sped up formation) Solar flux (sunlight catalyzes ozone formation from NO2)
Most abundant greenhouse gas
Carbon dioxide (70% of enhanced greenhouse effect vs methane -24%, nitrous oxide = 6%)
T or F: Anthropogenic emissions to atmosphere of CO2 are large
False, small (from combustion of fossil fuels such as biomass, coal, oil or gas for energy production)
*1750 industrial revolution = 40% increase in CO2
What happens if CO2 is double to 700 ppm
temperature increase by 6C
Vapor-phase atmospheric organics excluding carbon monoxide and carbon dioxide includiing pure hydrocarbons containing C and H only and species which contain o2 and cl
Volatile Organic compounds (same source as CO2)
Most abundant VOC in atmosphere (~1800 ppb) from natural sources ie wetlands and domestic ruminants
Methane
Other minor sources of methane
→ Biomass burning
→ Coal mines
→ Landfills
→ Sewage disposal
T or F: CO2 is more efficient in warming than methane
false, methane - 30 x more efficient and more efficient in trapping radiation than CO2
How is methane removed from atmosphere?
reaction with hydroxyl radical
One of the most significant envi health hazards in the modern workplace
Indoor Air Pollution
Why is Indoor Air pollution a special conern?
→ ~75-90% of time spent indoors
→ Many air pollutants known to be hazardous to health are emitted indoors
→ Indoor environments trap pollutants (levels vs outside: 2-5x higher, no ventilation/exhaust)
→ Energy conservation measures involving air tightening of building and lowered ventilation standards
→ Building occupancy
→ Human activities inside the structure (ex. Sweeping)
→ Gas-off from synthetic building materials (ex. Ceilingasbestos, paint- lead)
→ Reliance on forced air ventilation systems
Indoor air pollutants found in soil and groundwater
radon and radioactive progeny
Formaldehyde, asbestos, vinyl chloride and organic fumes are found in this indoor air pollutant source
Building materials and furnishings (carpeting, paint, varnish, adhesives)
IAP from personal activities and hobbies
Cigarette smoking, fireplace smoke, solvent and glue fumes
IAP from appliances, cooking and heating
Carbon monoxide, natural gas, cooking odors, boiler, and heater fumes
Other sources of IAP
- Selected indoor Aeroallergens and aeropathogens such as bacteria, yeasts, viruses, fungi, amoeba, arthropods and dander from hamster, cat and dogs
- Building Related Illness (ie: Legionnaires’ disease)
- Air conditioning system
- Environmental Tobacco smoke (secondhand smoke)
What does AC system provide if designed properly?
thermal comfort (temp and humidity) and necessary ventilation
High humidity facilitates what?
growth of molds
*low= discomfort
Why is Envir Tobacco Smoke hazardous?
- Tobacco smoke contains thousands of chemicals (i.e. NOx, CO, Hydrogen cyanide, and 40 carcinogenic chemicals)
- Nonsmoking workers exposed to ETS have reduced airway functions
This is also known as tight building syndrom wherein buildings have identifiable problems but no specific pollutantswherein occupants exp. Acute health effects linked to time spent in building but no specific illness or cause can be identified
Sick-building syndrome
Symptoms of SBS
→ Respiratory tract infection → Skin irritation → Headache → Dizziness → Nausea → Fatigue → Concentration problems
T or F: SBS symptoms diminish or cease when occupants leave the building
TRUE
SBS is related to what
Multiple chemical sensitivity
