Indoor and Outdoor Air Pollution
Introduction and BackgroundWhat Are the Problems?
A person inhales approximately 30 m3 (or 35 pounds) of air per day Roughly 6 times more than the food and drink consumed per day��Exposure to air pollutants is continuous (and involuntary)��Lung disease is the third leading cause of death in the U.S. (~335,000 deaths per year)��Asthma is the most common chronic illness in children−Leading cause of hospital admissions of childrenCAA Classification of Air Pollutants
“Criteria” pollutants−Ubiquitous−Not very toxic−PM, CO, NO2, SO2,Pb Hazardous air pollutants (HAPs)−Sources may be limited and industry specific−More toxic and even carcinogenic−~188 chemicals−For example, −Heavy metals (chromium, mercury, cadmium, vinyl chloride)−Organics (benzene, formaldehyde, perchloroethyleneCriteria Pollutants
Emitted from many large diverse sources, Omnipresent and, pose the greatest overall threat to human health Assumption: the adverse health effects are not cancerous, and their dose-response relationship exhibits a threshold. Sources: Transportation46%, Fuel combustion (stationary sources) 29%, Industrial processes 16%, Miscellaneous 7%, Solid waste disposal 2%. Emissions: CO 48%, SO2 16%, No2 16%, PM 5%.Particulate matter
Particulate matter−Solid or aqueous particles 0.01 to 1 µ m −Smallest particles (aerosols) can remain suspended−Below ~ 2.5 µ m are capable of penetrating all sites of the respiratory tract Porosity such that they absorb or adsorb other gases, liquids, and solidsSome Common Types of Particulate Matter
Aerosols−Any tiny solid or liquid particle Dusts−Solid particles from grinding or crushing Fumes−Occurring when vapors condense Mist, fog−Liquid particles Smoke, soot, ash−Solid particles, mostly carbon, from combustion Smog− originally meant smoke plus fogHazardous Air Pollutants (HAPs)
�� was specified at 1990.��HAPs are more toxic than criteria pollutants; they “. . . may reasonably be expected to result in serious irreversible . . disease, including cancer”
HAP Sources
61% Point sources,- Large industrial complexes –Chemical plants–Oil refineries–Steel mills –Marine tank vessel loading.21% Mobile sources,18% Area sources (non-point sources)–Dry cleaning operations–Solvent cleaning–Secondary lead smelters and chrome plating–Commercial sterilizersThe Clean Air Act (CAA): Underlying Philosophy
��Everybody should have the same degree of protection��Most susceptible subgroups of individuals (e.g., asthmatics, children) are to be protectedAs air moves across the continent from west to east, each population area adds to the total pollution in the atmosphere.Health Effects Associated with Air Pollution
Acute −Loss of lung function (FEV1by spirometry)−Symptoms of irritation (cough) − Disability (absenteeism, increased need for medication, increased emergency room visits, hospitalization) −Increased mortality rate (respiratory and cardiovascular deaths)Chronic −Impaired lung growth (spirometry) −Accelerated lung aging (spirometry) −Damage to other organ systemsCancerCriteria Pollutants and Susceptible Subpopulations
SO2−Persons with increased airway reactivity (asthmatics)CO−Persons with arteriosclerotic disease affecting coronary vessels (angina patients)Pb−Fetuses and children��PM10−Mortality—the elderly with cardiovascular and pulmonary disease−Morbidity—children��NO2−Children (respiratory illness).
Indoor Air Pollution: Reasons for Special Concern
��~75–90% of time spent indoors−Time depends on season, age, gender, health status��Indoor environnements trap pollutants−Levels may be 2 to 5 times higher than outside.��Many air pollutants known to be hazardous to health are emitted indoorsSources of Indoor Air Pollutants
Soil and groundwater →Radon and radioactive progenyBuilding materials and furnishings (carpeting, paint, varnish, adhesives)→Formaldehyde, asbestos, vinyl chloride, organic fumesPersonal activities and hobbies→Cigarette smoking, fireplace smoke, solvent and glue fumesCooking, and heating→Carbon monoxide, natural gas, cooking odors, boiler and heater fumes.More Sources of Indoor Air Pollutants
Household chemicals (bleach, oven cleaner, insect sprays, nail polish, hair spray) →Ammonia, hydrogen chloride, pesticides, organic fumes, aerosolsElectronic equipment and wiring →Organic fumes, electromagnetic radiationPets →Hair, feces, proteins, dustPlants →Pollen, etc