QUESTIONS

1. A dinosaur extinction theory suggests that massive heating of the Earth's atmosphere in the path of a falling asteroid would have led to extremely acid rain, killing the land vegetation and hence the dinosaurs' food supply. What acid would have been involved? 

POLLUTION & HEALTH

MORBIDITY: refers to the state of being diseased or unhealthful. Morbidity refers to the incidence of ill health in a population

- expressed as a probability of illness or similar metric

MORTALITY: is the state of being mortal (having a finite life). Mortality refers to the incidence of death in a population

- expressed as number of deaths per 1000 individuals per year

SOME DEFINITIONS…

SOME EFFECTS…

ACUTE: irritation to the eyes, nose and throat, and upper respiratory infections such as bronchitis and pneumonia, headaches, nausea, and allergic reactions. Short-term air pollution can aggravate the medical conditions of individuals with asthma and emphysema

CHRONIC: respiratory disease, lung cancer, heart disease, and damage to the brain, nerves, liver, or kidneys. Continual exposure to air pollution affects the lungs of growing children and may aggravate or complicate medical conditions in the elderly.

COSTS: healthcare, lost productivity in the workplace, and human welfare

bold = included in Lave and Seskin, 1970 study

WAYS THIS IS STUDIED…

EPIDIOLOGICAL STUDIES: mortality and morbidity rates (often from governments), need to classify cause of death or control for other variables (eg. smoking habits, occupational exposure, genetics, etc.) can fail to find significant relationships or find spurious ones due to unmeasured variables must find a relationship that is so strong that it is extremely unlikely that missing variables could be the cause

EPISODIC RELATIONSHIPS: relate daily/weekly mortality (or mobidity) rates to coincident indices of air pollution problem: air pollution usually more subtle (someone killed during an air pollution event likely gravely ill) also need to control for other factors (eg. absences from Monday during an air pollution event might be related to weekend activities, not air pollution health impacts)

Tools: statistical analysis, multiple regressions, thorough uncertainty and significance analyses

HARVARD SIX CITIES STUDYCohort study: 8111 adults followed from 1974-1991 (annual surveys)

[Dockery et al., 1993, NEJM]Associated fine-particulate pollution with excess mortality. No observable threshold.

AMERICAN CANCER SOCIETY: PM EFFECTSCohort Study: 1.2M participants in American Cancer Society tracking 1982-1998

~1/2 linked with air pollution data for metropolitan areas in the U.S.

Each 10-μg/m3 elevation in fine particulate air pollution was associated with approximately a 6%, and 8% increased risk of cardiopulmonary, and lung cancer

mortality. [Pope et al., 2002, JAMA]

Mortality Relative Risk (RR) Ratio Associated With 10-μg/m3 Differences of PM2.5 Concentrations

REDUCED LIFE EXPECTANCY DUE TO PM

[Pope et al., 2009, NEJM]

A decrease of 10 μg/m3 in the concentration of fine PM was associated with an estimated increase in mean life expectancy of 0.61 years

OZONE CORRELATED WITH RESPIRATORY HOSPITAL ADMISSIONS

Episodic study: acute respiratory health effects at 168 hospitals in Ontario (1983-1988)

5% of respiratory hospital admissions in May-Aug associated with ozone

[Burnett et al., 1994, ER]

Adjusted admissions (binned by decades of ozone)

MAIN ISSUES WITH HEALTH-POLLUTION STUDIES

1. Controlling for other variables (intensive effort required to get true picture of lifestyle and impacts)

2. Understanding cause of death (particularly how to get information once someone in a cohort study has passed away!)

3. Effort required for long-term cohort studies

4. Approximating exposure with ambient monitoring networks Working more on personal exposure monitoring

5. Getting detailed information on size, composition of particles and how they affect health

6. Scaling up! Assuming all populations respond alike (economically, environmentally, racially)

APPLICATION OF EPIDIOMIOLOGICAL STUDIES: INVESTIGATING THE LINK BETWEEN RISING CO2

AND AIR POLLUTION MORTALITY

[Jacobson, 2008]

T leads to increases in O3

H2O increases O3, except in low NOx conditions

Found that pre-industrial to present day increase in T (~ 1K) and water vapour (~1 ppb) over US, led to an increase of 415 deaths/yr due to O3 exposure in the US

(8500 dealth/yr worldwide). Previous studies estimate up to 15,500 deaths/yr due to 1 ppb change in O3

Pre-industrial to present-day population weighted 8-hr O3 = 0.72 ppb

y= health effect change (death rate)x=mixing ratio change=fractional increase in risk per unit xyo= baseline health effect rate P=population exposed to a min threshold[Ostro et al., 2006]

IMPACT OF BLACK CARBON EMISSION REDUCTIONS ON HUMAN MORTALITY

Estimate that halving global anthropogenic BC emissions avoids

157 000 annual premature deaths globally, mostly near the source region

(esp. Asia).

[Anenberg et al., 2011]

AF=attributable factorRR=relative riskX=change in PM2.5=concentration response factoryo=baseline mortality rate

Avoided deaths for halving emissions

GLOBAL HEALTH INDICES FROM SATELLITE OBSERVATIONS

Multipollutant Air Quality Health Index (AQHI): [Stieb et al., 2008]AQHI = 0.09 x NO2 (ppb) + 0.05 x PM2.5 (ug/m3) + 0.05x O3 (ppb)

~ excess mortality risk (%)

[Randall Martin, Dalhousie]

NO2 and O3 from OMI, PM2.5 estimates from MODIS/MISR