A study by Harvard researchers Eileen McNeely et al titled "Cancer prevalence among flight attendants compared to the general population" was published in Environmental Health on June 26, 2018. The article describes occupational exposure of flight attendants to known and probable carcinogens including cosmic ionizing radiation at flight altitude, Circadian rhythm disruption, and poor cabin air quality. The researchers surveyed participants in the Harvard Flight Attendant Health Study and compared the prevalence of self-reported cancers to equivalent information from a nationally representative sample. Based on statistical analyses, the researchers found a higher prevalence of breast, melanoma and non-melanoma skin cancers among flight attendants compared to the general population. The authors describe some of the limitations of their study; nonetheless, the research is a significant contribution to the body of knowledge about occupational health and safety risks for flight attendants.
A research article, "Volatile chemical products emerging as largest petrochemical source of urban organic emissions", by McDonald et al, published in Science on February 16, 2018, highlights the contribution of volatile chemical products (VCPs) like pesticides, printing inks, adhesives, cleaning agents, and personal care products in emission inventories of volatile organic compounds (VOCs). With automotive VOC emissions on the decline in the United States and Europe, the relative importance of other sources of VOC emissions is growing. The authors note that as diesel particle filters and oxidation catalysts become more widespread in the transportation industry, the fraction of fine particulate matter (PM2.5) arising from VCPs will grow. Given that people spend most of their time indoors, "consumer uses of VCPs likely remain key sources of human exposure to air toxics relative to fossil fuels".
Air Pollution and Birth Defects
An article featured in last week's The Globe and Mail ("Air pollution around conception tied to birth defects: study" by Lisa Rapaport) highlights the findings in a recent US study that women exposed to polluted air during the month right before or after they conceive may be more likely to have babies with birth defects. Researchers reviewed data for almost 290,000 infants born in Ohio from 2006 to 2010, cross-referencing the records with air pollution measurements near their mothers' homes. The researchers focused on PM2.5, and found a small but statistically significant increased risk of congenital birth defects.
The Synergist weekly feature, "The ABCs of Wildfire Residue Contamination Testing" by Alice Delia and Daniel Baxter, discusses post-wildfire assessments of the indoor environment. The key concerns are particulate residues, volatile organic compounds (VOCs), semi-volatile organic compounds (SVCOs), and metals. The article discusses technologies and methods that can be used to test for contaminants as well as the advantages and disadvantages of the various methods. Although there is no single analytical test that can be used to determine whether a building is "safe", selecting the right types and combination of tests can provide the necessary insight to make an informed evaluation.
The ANSI/ASHRAE/IES Standard 100-2015 Energy Efficiency in Existing Buildings provides comprehensive procedures to improve the energy efficiency of buildings. Although Standard 100 provides direction for residential and non-residential buildings, the purpose of this article is to describe the application of Standard 100 to residential buildings.
The Energy-Use Intensity (EUI) of a building is calculated as the annual net energy use divided by the gross floor area (expressed either as MJ/m2 or BTU/ft2). When calculating the EUI, building energy-use data for twelve consecutive months within the last 18 months must be considered. The energy targets for a building depends on the climate zone in which the building is located. Table 1 shows the climate zone number for major cities in Canada together with the Energy Targets for single-family detached residential buildings. Buildings that meet their energy targets are not required to perform an energy audit.
Table 1 - Energy Target for Single-Family Detached Homes in Major Canadian Cities
Performing an Energy Audit
In accordance with Standard 100, buildings that do not meet their energy targets are required to undergo an energy audit. As part of the audit, the historical energy use is allocated to end uses such as HVAC, lighting, domestic hot water, and electrical plug loads. Once the energy audit has been completed, the energy efficiency measures (EEMs) to be implemented are selected and the estimated energy savings for the EEMs is calculated. An adjusted EUI is calculated that considers what the EUI would be with the EEMs implemented. Once the adjusted EUI meets the energy target, then the EEMs are implemented.
The energy savings is expressed in both cost units as well as energy units. The cost of implementing each EEM is included together with the simple payback for each EEM or the recommended package of EEMs. Once the EEMs have been implemented, the building's EUI is monitored until twelve consecutive months of data demonstrate that the energy target has been achieved.
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The June 2017 issue of the ASHRAE Journal features an article on measurement of indoor airborne particulate matter. The article cautions against comparing real-time nephelometric measurements of particulate matter to USEPA National Ambient Air Quality Standards for particulate matter or OSHA standards.
Nephelometers detect particles and measure light scattering by the particle. A mass concentration estimate can be obtained based on assumptions about optical properties and density. Real-time multi-fraction particle counters can be useful in refining building assessments beyond the use of CO2 concentrations as an indicator of ventilation. Although there are no health-based guidelines for PM limits using real-time count concentration values, comparing indoor results to outdoor results or assessing spaces over time can provide "practical, inexpensive guidance on managing the PM burden in a space" (p. 86). Fine particles have been associated with cardiovascular disease while coarse particles have been associated with respiratory disease, although there is an overlap in effects.
The CBC news featured an article today titled "Diesel pollution vastly underestimated, contributes to global deaths". The article discusses a research study published in Nature that suggests that air pollution from diesel vehicles is more than 50 percent higher than shown in government lab tests. The researchers estimated that the additional pollution equates to an additional 38,000 deaths from soot and smog in 2015.
Over the last two weeks, there have been several news stories related to high concentrations of carbon monoxide in indoor air leading to death. On March 23, 2017, Global News published an article, "16 Mandarin restaurant employees in Scarborough hospitalized with carbon monoxide symptoms". On April 1, 2017, CTV featured an article, "Hotel carbon monoxide leak kills child, sickens others in Michigan", about a carbon monoxide leak at a hotel that killed one child and made approximately twelve other people ill. On April 3, 2017, CBC News published an article, "A life off the grid: Idyllic then deadly" about four people killed from carbon monoxide poisoning in British Columbia as a result of carbon monoxide leaking from a propane-powered hot water tank. On April 2, 2017, the Globe and Mail featured an article, "Most Canadians unprotected against carbon monoxide, fire chiefs say".
Carbon monoxide is an odourless, colourless, tasteless gas that is a byproduct of fuel combustion, irrespective of the type of fuel used. Appliances or motor vehicles that produce carbon monoxide become a risk when there is poor ventilation, and the carbon monoxide accumulates to dangerous levels. At low concentrations of carbon monoxide, adverse health effects may be experienced including tiredness, headaches, muscle weakness or shortness of breath. At high concentrations or when exposed to low concentrations of carbon monoxide over time, symptoms may include dizziness, chest pain or difficulty thinking.
Carbon monoxide combines with the oxygen-carrying sites on hemoglobin in the blood, with an affinity 210 to 240 times higher than that of oxygen. The resulting carboxyhemoglobin is unable to carry oxygen. Occupational health and safety codes recommended a maximum 8-hour exposure limit of 25 ppm.
In order to reduce the risk of exposure to high levels of carbon monoxide in indoor air, the following actions are recommended:
An article in Popular Science by Sara Chodosh and Kendra Pierre-Louis titled "Here's how air pollution kills 3,450,000 people a year" discusses a recently released study on air pollution and premature death. The study, published in Nature, shows that approximately 12% of premature deaths were caused by air pollution released elsewhere in the world. Particulate matter that is 2.5 microns and smaller (PM2.5) is especially problematic because of its ability to transfer from the lungs to the cardiovascular system. The article also indicates that the Clean Power Plan, which President Trump just rescinded, would not only have had significant benefits in terms of greenhouse gas reductions, but it also would have significantly reduced PM2.5, saving lives.
The Globe and Mail featured an article on March 24, 2017 titled "Asbestos found in U of T labs stokes concern from faculty, students". The article indicates that dust containing asbestos has been found in multiple labs at the University of Toronto's medical-sciences building. A major renovation has been undertaken of the building, which is almost 50 years old. Although any asbestos use will be banned in Canada by 2018, the University of Toronto incident illustrates the challenges associated with addressing the legacy of asbestos containing materials.