July 21 RE: Plant emissions…

July 21 RE: Plant emissions air quality, dust, and human health

Unconventional gas development can affect local and regional air quality. Emissions from the proposed huge bio-gas and waste depot plant will add to current high levels of air toxicants in the Coronation Drive area as reported in 2019 by ChemTRAC and from the National Pollution Release Inventory {NPRI) data that show emissions and releases to air from seven chemical industries, plus from Highland Creek wastewater treatment plant, this industrial park has the highest releases of non-cancer (e.g. pulmonary, developmental, reproductive) toxicants in Toronto, and is among the Toronto areas with the highest releases of cancer-causing agents. The health of residents should not be further compromised by additional emissions of toxic pollutants from the proposed largest bio-gas plant in Canada. At the very least a Health Impact Assessment (HIA) is warranted to protect the health and well-being of our community prior to any decision being made on the ECA.

The Amended Compliance Agreement (ECA) has listed six expected chemical emissions to air, five of which are recognized in the ECA as having health effects: Carbon dioxide CO2, total reduced sulphur (TRS), sulphur dioxide (SO2), nitrogen oxides (NOx), methane (CH4), and particulates (PM2.5 and PM10). Five of these chemicals are major greenhouse gasses (GHGs), and are identified in the ECA as of concern for health effects. Surprisingly, particulates are not considered a health concern in the ECA, however the Canadian Environmental Protection Act identifies SO2 as a Priority Substance, and as “one of the principal precursors to PM10 which is toxic and constitutes a danger in Canada to human life or health.” Particulate exposure in this area has been found to exceed inhalation reference doses (HHRA 2015 intrinsik) so no additional emissions of particulates should be permitted . It is noted that CO2 emissions will be at three times the ministry’s limit.

Total Reduced Sulphur (TRS) / Hydrogen Sulfide (H2S)
TRS and H2S are sometimes used interchangeably as referring to the same substances. Hydrogen sulfide is extremely poisonous to humans and animals. The Ontario Ministry’s limit of 13 micrograms per cubic meter (ug/m3) and based on odour, not hazard, on a ten-minute exposure only , and in 1981 the World Health Organization recommended that ambient H2S levels not exceed 5 ppb during a 30-min period (WHO, 1981) . Ontario’s Air quality concentration limit is 7 ug/m3 for 24 hours, based on odour .
A 2019 meeting in South Africa on hydrogen sulfide (H2S) noted that almost any exposure to that agent has some negative effect. The atmospheric residence time of H2S is typically less than 1 day in summer but may be as high as 42 days in winter (resulting in prolonged and increasing levels of exposure. Background H2S air concentrations typically range between 0.11 ppb and 0.33 ppb, although concentrations in urban areas can be as high as 1 ppb. The effects of low-level , long-term exposure to ambient levels of hydrogen sulfide (< 1 ppm) in air are more difficult to estimate. At such levels and duration, expected symptoms of exposure could include visual complications, olfactory fatigue, nausea, respiratory irritation, and possible headaches due to the sensitivity of those systems to hydrogen sulfide exposure . Hydrogen sulfide doses over more prolonged duration result in more serious symptoms.
H2S Emissions from use of the Emergency Bio-gas flare or Use of the Emergency Pressure Relief Valve
Use of the emergency pressure relief valve (PRV) will emit hydrogen sulfide as total reduced sulfur and H2 S. The emergency PRV is a mandatory safety precaution as per Bio-gas Code Although it is stated that it is unlikely the PRV will have to be used, the document provides he worst case ambient conditions resulting from use of the PRV modeled using raw bio-gas that contain up to 500 ppm H2S. These numbers are not reassuring; 500 ppm of hydrogen sulfide to ambient air would be dangerous even for short inhalation exposures. There is a PRV on both anaerobic digesters.

Many of the chemicals associated with the operation of this plant are known to have adverse effects on pulmonary systems. In such cases cumulative (additive or synergistic) effects should be calculated. Cumulative risk to health has also been defined broadly to mean the risk posed by multiple chemicals and other stressors that cause varied health effects. The additional stressors to health and well-being from this proposed bio-gas plant, operating 24/7/365 are increasing traffic, noise, odours and dust, alongside ever-increasing air pollution. All these factors should demonstrate clearly that a plant of this size and type does not belong in the vicinity of a heavily populated area, or near the source of Scarborough’s drinking water. A zoning permission of any type should not exempt industries from environmental and health oversight.

Under the Ontario’s ERO Statement of Environmental Values, Part 3 Application; both the environment and human health are included “The Ministry uses a precautionary, science-based approach in its decision-making to protect human health and the environment”. These environmental values that , include concern for human health should also apply in Environmental Compliance Approvals (ECAs). At the very least a Health Impact Assessment (HIA) is warranted to protect the health and well-being of our community prior to any decision being made on the ECA.