AIR POLLUTION

                                                                                                            

 Environmental Health:

What is air pollution

The result of emission into the air of hazardous substances at a rate that exceeds the capacity of natural processes in the atmosphere to convert, deposit, or dilute them…

Factors that affect air pollution:

•         Emissions (traffic, industrial, domestic)

•         Geography (terrain)

•         Weather conditions (rain, winds, humidity)

•         Season

•         Time of day

•         Population density

•         Indoor vs outdoor

Types of air pollution:

§  Aerosols

Particulates solid phase

Dust

Ash

Fumes

Solid and liquid

Smoke (from combustion)

Coastal aerosols

Liquid

Aggregate gases (sulfate, nitrate)

§   Gases

³ COx

³ SOx

³ NOx

³ PAH

Six primary or “criteria” air pollutants:

§  Carbon monoxide (CO)

§  Ozone (O₃)

§  Nitrogen dioxide (NO₂)

§  Sulfur oxides (SO_x)

§  PM_2.5 and PM₁₀

§  Lead (Pb)

Types of air pollution:

§  Individual pollutants

§  Reducing pollution (SO2)

³ Acid rain (fog)

³ Corrosive, eroding

§  Photochemical pollution

³ Aldehydes, electrophilic HCs

³ Oxidative, carcinogenic?

§  Mixtures and complex patterns

Sources of combustion:

·       tobacco

·       Power plants

·       Incinerators

·       Automobiles

·       Industry

Absorption in lungs

•         As gas, directly into blood stream

•         As particles, deposited onto bronchiolar and alveolar surface

–       Uptake by phagocytosis

–       Trigger of inflammatory response

–       Trigger of allergic response

–       Lung tissue scaring

US Regulation history:

•         1947 CA - Air pollution control Act

•         1955 - Truman’s Air pollution control Act

•         1963 Federal - Clean Air Act (1967 am)

•         1965 Federal - Motor vehicle Air pollution control Act

•         1970 The Clean Air Act: national level (EPA)

–       O₃, SO₂, NO₂, CO, PM, Pb, total hydrocarbons (dropped)

•         1970 Lead is banned as fuel additive

•         1990 CCA amendment: 118 chemicals, some carcinogenic

–       Maximum achievable control technology

–       Additional risk assessment if health effects beyond the MACT level

–       Emission standards for motor vehicles (CO solution - MTBE new problem)

•         1997 New standard for PM_2.5

Clean Air Mercury and Interstate rules:

•         On March 15, 2005, EPA issued the Clean Air Mercury Rule to permanently cap and reduce mercury emissions from coal-fired power plants for the first time ever. This rule makes the United States the first country in the world to regulate mercury emissions from utilities.

•         On March 10, 2005, in a separate but related action, EPA issued the Clean Air Interstate Rule (CAIR), a rule that will dramatically reduce air pollution that moves across state boundaries.

•         Together the Clean Air Mercury Rule and the Clean Air Interstate Rule create a multi-pollutant strategy to reduce emissions throughout the United States.

Epi studies of air pollution:

Outdoor studies predominantly

–       Cohort studies (Harvard six cities; American Cancer Society; Adventist Health Study of Smog)

–       Biomarkers (breath, BAL, blood)

–       Lung function (FEV1, FVC, FEF25-75)

–       Symptoms (coughing wheezing, shortness of breath, cardiac function)

–       Long-term/chronic (confounders)

•         Retrospective

•         Prospective

–       Time series

•         National Morbidity, Mortality and Air Pollution Study (NMMAPS)

•         Air Pollution and Health, a European Approach (APHEA)

Chronic effects of air pollution:

–       Los Angeles basin: “aging-like” effect on lung function

–       Netherlands: 12y, SO₂ and PM

–       Rural PA: higher incidence of respiratory symptoms

–       Harvard Six Cities Study: >15y, 20,000 people SO₂ and PM

–       Overall reduced lung function, bronchitis

–       Cancer risk: 2000/year vs 100,000/year from smoking - associated with PM/VOC combinations.