Health Fact Sheets

More health facts relating to polutants and standards.

 C4CA Health Facts #2 re: Pollutants and Standards

1. Fine Particulate Matter (PM2.5) is of the greatest concern.

The most significant pollutants in Ontario are fine particulate matter (PM2.5), ozone (O3), nitrogen dioxide (NO2), sulphur dioxide (SO2), and carbon monoxide (CO). Most health damage attributable to air pollution arises from long term exposure to fine particulate matter.1 Particulate matter is the general term used for a mixture of solid particles and liquid droplets in the air. Fine particulate matter (PM2.5) contains particles of 2.5 microns in diameter or less. PM2.5 arises principally from the combustion of fossil fuels and is comprised largely of nitrates, sulphates, elemental carbon and organic carbon compounds.2

Scientific evidence supports a causal relationship between exposure to PM2.5 and premature death.3 This exposure can involve short term periods as brief as one day, or longer exposures of only one or two years.4 The premature mortality is largely due to cardiovascular events, although PM2.5 also worsens respiratory diseases.5 Extensive study has shown that there is no apparent lower level or threshold below which PM2.5 has no effect on population health.

Indeed, for every 1 μg/m³ increase in the level of PM2.5 to which the public is exposed long term, there will be a 1% increase in premature deaths.6 The Town of Oakville has estimated that at current levels of PM2.5 in ambient air, there will be 80 premature deaths in Oakville attributable to PM2.5 pollution every year.7

2. Most PM2.5 cannot be measured at the stack.

PM2.5 includes both primary fine particulates that are emitted directly from industrial stacks, and secondary fine particulates derived from the chemical transformation of simultaneously emitted precursor gases.2 These precursors include nitrogen oxides, sulphur dioxide, volatile organic compounds (VOCs) and ammonia. Secondary fine particulate formation occurs in the atmosphere at variable distances from the emitting source. In ambient air, the majority of the PM2.5 present is of secondary origin.8 If the contribution from an emitting source to any increase in secondary PM2.5 is not included in air modeling studies, the potential health damages attributable to this source will be underestimated. The TransCanada Draft Environmental Review Report for the proposed Oakville power plant does not consider secondary fine particulate matter.

3. Ontario air quality standards are not protective of human health.

The World Health Organization (WHO) has carried out exhaustive analyses of peer-reviewed scientific health research conducted on the adverse effects of pollutants in ambient air.9 It appears that guidelines currently in place in most jurisdictions for pollutants such as PM2.5, NO2, SO2, CO, and O3 are outdated and NOT protective of health10 (see also Table 1). Moreover, these standards and guidelines are not always legally binding and thus not enforceable, putting public health at risk.

Among the Canadian provinces, only British Columbia has taken the initiative to formally regulate PM2.5 levels. In April 2009, British Columbia11 adopted new ambient air quality criteria for PM2.5. They include: a 24-hour objective of 25 !g/m3; an annual objective of 8 μg/m³; and an annual voluntary planning goal of 6 μg/m³.

Annual standards are intended to establish reasonably protective levels over the long term. This is critical with regard to fine particulate matter whose principle heath effects become increasingly evident with years of exposure even at relatively low levels. Ontario currently has no annual standard in place to regulate PM2.5; nor has any been proposed. The federal Canada Wide Standard for PM2.5 does not represent an annual standard and has no legal regulatory power.12

4. Adverse Health Effects of Nitrogen Oxides (NOx)

Nitrogen oxides (NOx) include nitrogen monoxide (NO), also known as nitric oxide, and nitrogen dioxide (NO2). Both are produced from interaction between nitrogen and oxygen at high combustion temperatures. Nitric oxide is the main form of NOx emitted from industrial stacks. Nitric oxide rapidly reacts with oxygen or ozone in the atmosphere to form nitrogen dioxide. NO2 is a reddish brown gas with a pungent and irritating odour and is a major contributor to visible smog.13 Nitrogen dioxide has adverse health effects at much lower levels than nitric oxide.14

NOx pollution has been associated with inflammation in the lungs, increased susceptibility to both viral and bacterial respiratory infections, and aggravation of asthma and allergies.15 People exposed to NOx account for a substantial number of increased hospital admissions for respiratory causes, especially asthma.16 There is also a link between NOx and increased risk of cardiopulmonary mortality.17

NOx is also a key precursor for the formation of nitrates (NO3), which comprise a major proportion of secondary PM2.5.13

5. Adverse Health Effects of Ground Level Ozone (O3)

Ozone is a major component of smog. Ground-level ozone is not emitted directly into the atmosphere but arises secondarily, like secondary PM2.5, from precursor emissions of NOx and VOCs.18 The formation and breakdown of ozone is a continuous process involving a complex series of chemical interactions driven by energy from the sun.

Ozone is toxic to the respiratory tract. Exposure to high levels of O3 results in chest tightness, coughing and wheezing, and people with respiratory and heart problems are at a higher risk of experiencing these ill effects. Ozone has also been linked to increased hospital admissions and premature death.18 A 2009 study on long-term ozone exposure and mortality demonstrated a 4% increased risk of death from respiratory causes associated with each 10 ppb (parts per billion) increase in ozone levels.19 In 2005, the Ontario Ministry of Energy commissioned a Cost-Benefit Analysis of its plan to replace coal-fired power plants with natural gas facilities. This analysis concluded that "building new gas generation facilities closer to urban centres will cause some local degradation of air quality in terms of ozone concentrations" and ozone levels in the Toronto area would be increased.20

6. Adverse Health Effects of Sulphur Dioxide (SO2)

Although the natural gas used by gas-fired power plants contains only low levels of sulphur, this sulphur generates a considerable quantity of SO2 (via combustion) due to the sheer volume of natural gas consumed by the plant in its operations.

SO2 exposure leads to wheezing, shortness of breath, and chest tightness. Continued exposure to elevated levels of SO2 can result in decreased pulmonary function, and increased risk of mortality.10 21 It is now known that the health damage associated with SO2 occurs at much lower levels of exposure than previously believed.22 Accordingly, the WHO has just recently cut its guideline for permissible SO2 levels to one-sixth of its previous value.

SO2 is also a precursor to sulphates (SO4), which are one of the main components of secondary PM2.5.21

7. Adverse Health Effects of Carbon Monoxide (CO)

Carbon monoxide is a colourless, odourless and poisonous gas produced primarily by incomplete combustion of carbon-based fuels.

Carbon monoxide enters the blood and reduces oxygen delivery to the organs and tissues. Exposure to high CO levels impairs central nervous system function and can result in headaches, confusion and dizziness.10 23 People with heart disease are particularly sensitive to CO. Recent evidence has shown an association between short-term exposure to ambient CO and increased risk of hospitalization for cardiovascular disease, even at levels well below current regulatory standards.24

Carbon monoxide also contributes to the formation of ozone.

8. Adverse Health Effects of Volatile Organic Compounds (VOCs)

Volatile organic compounds are carbon-based substances that vaporize easily. VOCs arise from the evaporation of solvents, paints or petrochemicals and combustion of fuels including natural gas. Some VOCs are produced by natural sources such as trees. Many VOCs of industrial or chemical origin have the potential to cause significant harm to human health. 25 VOCs are also important precursors for the formation of secondary PM2.5 and can interact with NOx to form ground level ozone.25

9. Ammonia (NH3)

When a gas-fired power plant utilizes a technology called selective catalytic reduction (SCR) to reduce its NOx emissions, ammonia is released into the air. At high concentrations, ammonia irritates the respiratory tract. Ammonia can also contribute to the formation of secondary PM2.5.26

10. Cumulative Effects

A key concern with the building of the proposed plant at the Oakville site is that it is completely unknown what the cumulative effects of all these pollutants will be. Scientific studies look at the effects of these substances on human populations only one at a time, or at best, two at a time. In the case of the Clarkson Airshed, the proposed plant will contribute PM2.5, NOx, ozone, CO, VOCs, and SO2 to an airshed that is already acknowledged as being overtaxed. Will the introduction of these additional pollutants to our airshed constitute an additive or synergistic assault on our health? The public deserves an answer to this question before any power plant is built.

Table 1. International Comparison of Ambient Air Quality Standards and Guidelines (see PDF)

Note: Although the WHO set a guideline for an annual mean for PM2.5 of 10 μg/m3 in 2005, subsequent reviews have demonstrated that in fact no safe level of PM2.5 exists.

REFERENCES - SEE PDF