7.5, 7.6 APES notes
Topic 7.5 Indoor Air Pollution
Skill Demonstrated
5.C Explain patterns and trends in data to draw conclusions.
Enduring Understanding
STB-2 Human activities have physical, chemical, and biological consequences for the atmosphere.
Learning Objective
STB-2.E Identify indoor air pollutants.
Impact of Housing on Indoor Air Quality
How Housing in Developing versus Developed Nations Impacts Indoor Air Quality
Developing Nations
Greater use of subsistence fuels:
Biomass releases harmful indoor air pollutants such as:
CO (Carbon Monoxide)
PM (Particulate Matter)
NOx (Nitrogen Oxides)
VOCs (Volatile Organic Compounds)
Often indoor fires are used with poor ventilation, leading to high indoor air pollutants
Developed Nations
Reliance on commercial fuels (Coal, Oil, Natural gas)
Typically used in well-ventilated furnaces/stoves
Indoor pollutants come from various chemicals exuded by household products such as:
Cleaners
Adhesives
Insulation
Carpets
Sources of Indoor Air Pollution in Developed Countries
Common sources of pollution within homes include:
Biological Pollutants:
Mold
Pollen
Dust mites
Bacteria
Viruses
Chemical Pollutants:
Tobacco smoke
Wood smoke
Household products and pesticides
Gases such as:
Radon
Carbon monoxide
Building Materials:
Asbestos
Formaldehyde
Lead
Key Points about Different Types of Indoor Air Pollutants
Pollen
Viruses
Cleaning Chemicals
Pet Dander
Tobacco Smoke
Environmental Pollutants
Germs
Bacteria
Particulate Matter and Asbestos
Particulate Matter (PM)
PM is a widespread indoor air pollutant that includes:
Smoke (from biomass combustion, cigarettes)
Dust
Asbestos
Asbestos:
Long silicate particle found in old insulation, floor tiles, and near heating elements
Health impacts:
Associated with cancer
Causes asbestosis (chronic lung disease)
Enters the air if disturbed, impacting the respiratory tract
Tobacco Smoke
Unique as an indoor air pollutant due to its well-documented health consequences
Impacts both smokers and non-smokers
Produces large amounts of harmful gases and particles, significantly affecting indoor air quality
Carbon Monoxide (CO)
Characteristics:
Colorless, odorless, toxic gas
Difficult to detect without a CO detector and can be fatal as it acts as an asphyxiant
Health impact:
CO binds to hemoglobin, displacing oxygen in blood
Sources of CO include:
Appliances such as furnaces, water heaters, ranges, and some dryers
Incomplete combustion of any fuel source can occur due to lack of oxygen or low temperature
Gas Appliances
Produce pollutants such as:
Carbon dioxide
Carbon monoxide
Nitrous oxides
Water vapor
Risks increase with improper venting or negative air pressure around non-sealed gas appliances, causing backdrafting where combustion pollutants enter the house
Symptoms of Carbon Monoxide Poisoning
Mild Symptoms:
Slight headache
Nausea
Vomiting
Medium Symptoms:
Severe headache
Confusion
Drowsiness
Fatigue
Fast heart rate
Extreme Symptoms:
Unconsciousness
Convulsions
Cardio-respiratory failure
Death
Volatile Organic Compounds (VOCs)
Large range of evaporated substances found in household products, including:
Cleaners and deodorizers
Formaldehyde emitted by building materials (like carpet glue and particle board) and furnishings (plastics and fabrics)
Pesticides, cooking fumes, and even body odors
Health Effects:
While many VOCs are just nuisances, some, like formaldehyde, can threaten health, sometimes at concentrations too low to be sensed
Common symptoms include eye irritation and inflammation of air passages
Radon Gas
Characteristics:
Naturally occurring radioactive gas from the decay of uranium (Radon-222) in soil, rocks, and groundwater
Pathways into homes include:
Entering through the basement or cracks in walls or foundation
Dissolved in groundwater from wells
Concentration varies regionally and locally
Controlling Radon in the Home
Prevention Measures:
Test levels using a kit or professional services
Seal basement cracks
Improve ventilation in the home
Radon Reduction System:
A small fan connected to a PVC pipe system lowers the soil gas pressure and vents radon-rich air safely into the atmosphere instead of the home
It pulls air from beneath the foundation slab, exhausting harmlessly at roof level
Effects of Radon
Health Implications:
Exposure to radon can lead to radon-induced lung cancer, which is the second leading cause of lung cancer in America
Can damage lung cells and commonly has early signs including persistent cough
Dust
Dust: Fine particles that enter the respiratory tract, leading to exacerbation of conditions such as asthma, Chronic Obstructive Pulmonary Disease (COPD), and respiratory irritation
Mold
Mold: Fungus thriving in dark, moist, poorly ventilated areas
Common locations include areas associated with leaks, pipes, or behind cabinets
Conditions that lead to mold growth: Warm moist air + cool surfaces leading to condensation
Health implications include:
Causes asthma or allergies
Can destroy wood products
Accelerates rusting of metal components in buildings
High indoor humidity can cause “off-gassing” of toxins from furniture or cleaning products
Solutions:
Fix leaks
Increase ventilation
Use a dehumidifier
Lead
Phased out of paint as of 1978
Older houses with chipping paint can lead to inhalation of dust or ingestion of paint chips by small children
Lead can enter water through lead pipes, albeit less commonly (e.g., Flint River Michigan Water Crisis 2014)
Health Effects:
Lead is a neurotoxin, especially harmful to children
Causes brain damage, slows growth, and leads to learning, behavior, speech, and hearing issues
Remember to Do the Following
Watch all AP Classroom Videos for Topic 7.5 from today’s lesson
Add notes while reading and watching videos
Ensure understanding of the following:
Identify common indoor air pollutants
Describe effects of indoor air pollutants such as PM and Asbestos, CO, VOCs, Radon Gas, Dust & Mold, and Lead
Topic 7.6 Reduction of Air Pollutants
Skill Demonstrated
7.D Use data and evidence to support a potential solution.
Enduring Understanding
STB-2 Human activities have physical, chemical, and biological consequences for the atmosphere.
Learning Objective
STB-2.G Explain how air pollutants can be reduced at the source.
Strategies for Reducing Air Pollutants at the Source
Legislation
Vehicle Technology
Coal Power Plant Reduction Methods
Questions to address:
What can realistically be done to reduce air pollutants?
Legislation to Reduce Air Pollutants
Importance of public health-oriented air regulations
Clean Air Act:
Established in 1970, with updates in 1977 and 1990
EPA sets acceptable levels for air pollutants and monitors emissions from power plants
Enforces regulations through taxes, lawsuits, and fines on corporations releasing excess pollutants
Pollution Credits (similar to ITQs from fishing):
Companies that reduce emissions below limits earn EPA credits, which can be sold to companies exceeding their caps
CAFE Vehicle Standards
CAFE stands for Corporate Average Fuel Economy Standards in the US
Regulates vehicle manufacturers to produce more fuel-efficient vehicles
Greater efficiency results in the burning of less gasoline, lowering emissions of NOx, PM, CO, and CO2
Vehicle Technology to Reduce Air Pollutants
Key Technologies Include:
Vapor Recovery Nozzle:
Air pollution control device on gasoline pumps preventing fumes from escaping into the atmosphere while refueling vehicles
Catalytic Converters:
Device for internal combustion engines converting harmful exhaust pollutants (CO, NOx, hydrocarbons) into less harmful molecules (CO2, N2, O2, H2O)
Coal Power Plant Reduction of Air Pollutants
Common Methods Include:
Wet Scrubbers:
Remove particulates and/or gases from industrial exhaust streams by spraying a mist trapping particulate matter in water droplets
Decreases NOx, SO₂, VOCs, and PM emissions, with the waste collected at the bottom
Cons: Requires more energy and generates water waste needing treatment
Dry Scrubbers:
Removes particulates/gases from industrial exhaust with low water usage and waste production
Utilizes calcium oxide to absorb and collect SO₂
Pros: Less expensive and more efficient than wet scrubbers for certain applications
Electrostatic Precipitator:
Filter utilizing static electricity to remove soot and ash (PM) from exhaust fumes before exit from smokestacks
Requires periodic discharge of collected particles that are transported to landfills
Individual Actions to Reduce Air Pollution
Decrease Vehicle Emissions:
Combine trips, carpool, public transport, walk, or bike
Plant Trees & Native Vegetation:
Trees help absorb CO₂
Reduce Energy Consumption:
Support renewable energy sources
Reduce Waste:
Recycle and properly dispose of waste
Support Local Agriculture:
Grow own food or support local farmers
Remember to Do the Following
Watch all AP Classroom Videos for Topic 7.6 from today’s lesson
Add to your notes as you read and watch the videos
Ensure understanding of how air pollutants can be reduced at the source, focusing on: vapor recovery nozzles, the role of catalytic converters, and scrubbers on industrial exhaust streams