The Health Consequences of Air Pollution

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Air Pollutions Impact on Mortality

  • All causes mortality (death from any cause) has been associated with exposure to chronic air pollution in high quality studies (controlled prospective studies).
  • Mortality specifically related to the cardiovascular system, cardiopulmonary system and lung cancer have also been associated with air pollution.
  • The relationship between PM2.5 and mortality is linear (the higher the PM 2.5, the higher the mortality rate) at relatively low levels of pollution like those experienced in Kamloops.
  • Generally, for every 10 ug/m3 increase in PM 2.5, there is an increase in all cause mortality between 3-26%. A recent study suggests a 14% increase (Harvard Six Cities Study, most recent re-analysis).
  • In Kamloops , in 2011, the death rate (mortality rate) was 0.89% (777 deaths/87 654 population). Based on the study mentioned above, we estimated that for every 1 ug/m3 increase in PM 2.5, 11 extra people in Kamloops will die every year.
  • Conversely, decreasing ambient PM 2.5 leads to increased life expectancy.
  • A Canadian Study (Crouse, 2012) showed that the effects of air pollution on mortality are true at low concentrations (<8.7 ug/m3) of PM 2.5. The World Health Organization recommends a target PM 2.5 of 10 ug/m3. The BC Objective is 8 ug/m3 and the BC Planning Goal is 6ug/m3.
  • A 2011 paper (Pope et al) suggests that there may be a steeper increase in cardiovascular disease mortality associated with increased air pollution at relatively low levels of pollution (like those experienced in North America) but at high levels of pollution (like those in China and India) the increase in cardiovascular disease mortality may be relatively less.

Acute Stroke

    • Short term exposure to air pollution spikes (over hours) is an important risk factor for acute stroke even in otherwise healthy individuals.
    • Air pollution (such as PM 2.5 and smaller ultrafine particles) cause blood to clot more easily and the blood vessel walls to thicken more quickly. This increases the risk of stroke.
    • Hardening of the arteries (atherosclerosis) due to air pollution can even happen in children and adolescents.

 

  • Increased levels of air pollution (PM 2.5), even at acceptable levels according to the World Health Organization air quality guidelines, are associated with acute stroke due to blockage of blood supply to the brain.
  • This increased occurrence of acute stroke leads to increased hospital admission rates for stroke.
  • Air pollution exposure also contributes to increased rates of fatal strokes, especially in warm weather months

Air Pollution’s Effect on the Brain

  • Air pollution results in accelerated aging and other degenerative changes in the brain.
  • Even children exposed to high levels of air pollution have evidence of the Parkinson’s disease protein marker and oxidative stress in their brains. They also show evidence of markers associated with Alzheimer’s Disease.
  • Children and adolescents are especially at risk because their brains are developing.
  • The negative impacts of air pollution on brain development and intelligence (measured at 5 years of age) can start before birth with prenatal exposure through the mother.
  • Children exposed to air pollution don’t do as well on brain function tests compared to children tested from clean air areas. The air pollution exposed children also tend to have smaller brain volumes and have evidence of brain tissue abnormalities on brain imaging.
  • Increased vehicle exhaust is related to cognitive decline (dementia/Alzheimers) in older people. The larger the dose, the bigger the effect.
  • Air pollution components reach the brain and can penetrate deeply (sometimes they enter the brain directly via the nose if the particles are ultrafine).
  • Air pollution exposure decreases IQ. This effect is also dose related.
  • There are also studies that indicate that air pollution has been linked (or correlated) with lower intelligence, poorer motor function, attention deficits and behavioral problems in children, decreased cognition in adults, multiple sclerosis, autism, Parkinson’s and other neurodegenerative diseases.

Pollution and the Heart and Blood Vessels

    • Air pollution is linked to hardening of the arteries (atherosclerosis).
    • Air pollution affects arteries at all stages of life (from the placenta to the older adult).
    • Air pollution causes low grade inflammation and narrowing of the blood vessels. It also causes changes that encourage blood to clot in the blood vessels. The impact can be seen almost immediately (heart attack), but chronic exposure to low concentrations are also associated with significant narrowing of blood vessels.
    • The rates of heart attack, stroke and death increase within hours of exposure to increased air pollution and stay higher for as long as 30 days after the exposure has ended.
    • Air Pollution can trigger changes in heart rate and rhythm.
    • Air pollution causes average blood pressure to increase within minutes. All organs are impacted by increased blood pressure.
    • There is an increase in Emergency Room visits for venous blood clot events following spikes in air pollution.
    • People with diabetes show more tendency to hardening of the arteries,blood clotting and inflammation compared to people without diabetes when exposed to air pollution.

 

  • Air pollution impacts exercise capability, even in people who are young, healthy and fit. Even the healthy develop the same indicators of inflammation,risk of blood clotting and increases in blood pressure and heart rate.
  • During the Beijing Olympics in 2008, there was a sudden drop in air pollution levels over several weeks due to a large government initiative. Young healthy adults had lower levels of inflammatory and blood clotting factors during the clean air period versus the pre and post Olympics period.

Pollution and the Lung

  • Healthy adults have decreased lung function measurement when exposed to air pollution.
  • Healthy children have smaller lung function/capacity when exposed to long term air pollution.
  • Brief exposure to ozone and particulate matter reduces lung function (even in young healthy adults) and the reduction can last for a week after the pollution exposure is over.
  • More coughing for children in the first year of life.
  • More infant bronchiolitis requiring care.
  • Premature babies have more pauses in breathing (apneic episodes).
  • Air pollution is associated with increased rates of hospitalization and death from respiratory diseases in people of all ages.
  • Air pollution aggravates almost all lung diseases and likely plays a causative role in reactive airways disease (e.g. asthma).
  • Short term exposure leads to more flares and emergency department visits for childhood asthma.
  • Long term exposure to air pollution leads to increased asthma hospitalizations in adults.
  • More hospitalizations and deaths for people with COPD.
  • Air pollution increases the risk of respiratory infections.
  • Streptococcus pneumoniae (a bacteria that causes pneumonia), sticks better to human airway cells in the presence of air pollution.
  • Air pollution exposure is linked to a small,but measurable, increase in the number of lung cancer deaths in non-smokers.
  • Air pollution is associated with increased rates of hospitalization and death from respiratory diseases in people of all ages.
  • People with cystic fibrosis have more fevers, coughs, shortness of breath, decreased lung function and weight loss when exposed to air pollution.

Cancer and Air Pollution

  • Air pollution is associated with higher rates of breast, lung, prostate, cervical, brain, stomach cancers, and childhood leukemia.
  • Air pollution is associated with decreased survival in breast cancer patients.
  • In 2012, the World Health Organization upgraded diesel exhaust to a group 1 carcinogen (for lung and bladder cancer)
  • Studies in miners have shown mortality from lung cancer increases in proportion to duration and intensity of exposure to diesel exhaust, even at low concentrations.
  • Relative risk of lung cancer death in non smokers increases in proportion to particulate concentration (PM2.5) in the air.
  • Associations between pollutant concentrations or residing close to high traffic areas have been shown for cancer of the lung, ovary, brain, prostate, bladder and breast.
  • The risk of certain childhood cancers is increased when mothers are residing in areas of high air pollution.

Pollution and Birth Outcomes

 

  • Air pollution causes changes in the placenta that inhibits exchange of nutrients to the fetus by impacting the blood flow.
  • Pregnant women exposed to more air pollution have higher risk of poor pregnancy outcomes including higher blood pressure, higher rates of pre-eclampsia, intrauterine growth retardation, premature births, low birth weight babies and babies with smaller head circumference.
  • Air pollution is associated with higher rates of birth defects including neural tube and cardiac birth defects.

Pollution and Fetal Development

  • Air pollution breathed by a pregnant mother causes changes in the cell structure of the fetus (epigenetics) that are associated with higher rates of asthma and decreased lung function in the child five years later.
  • Exposure to intermittent episodes of high air pollution is associated with damage to the DNA of sperm and causes a consequent increase in the rates of male infertility, miscarriages and other poor outcomes.
  • Children living near petrochemical industries are exposed to a particular type of air pollution that can damage their genes. Some types of industrial pollution is more genotoxic than traffic pollution.
  • Pregnant women exposed to more air pollution give birth to babies with changes to their genes, which can be passed on to multiple subsequent generations.

 

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