By Sharon McLeay Times Contributor
The question of “what’s that smell?” is still unsubstantiated for Nightingale area residents, after Calgary Region Airshed Zone (CRAZ) air quality monitoring was conducted this summer.
CRAZ Program Manager Mandeep Dhaliwal presented monitor findings to Wheatland County council on Nov. 21.
At the request of council, ambient air monitoring was done at two separate sites between July 6 and Aug. 22.
Dhaliwal said CRAZ began monitoring odour complaints in 2015. In general, most complaints in the Nightingale area came from a radius of about 10 kilometres to the Green for Life (GFL) compost site; however, Dhaliwal said odours are often hard to quantify.
“It should be noted that these results capture the site conditions of the air quality at a single moment in time,” he said.
Monitoring in Wheatland County saw the mobile unit set up in two different locations. For the equipment to work, it needs moving air currents, access to power and a clear instrument site line. Dhaliwal took samples at 6 a.m. and 7 a.m. He did not know if GFL was turning compost piles at the time.
Air quality sampling registers 67 compounds and all registered below the regulated air criteria. He said H2S, volatile organic compounds (VOC), temperature, wind speed and direction are recorded. Winds were northwest and southwest and corresponded to complaint areas. There were two samples for H2S in one hour that exceeded the three parts per billion limits; however, the system cannot detect specifically if it came from the GFL site, or upwind of the monitors.
“One might think this is coming from this facility, but there is nothing to indicate that it might not be from upwind to this facility,” said Dhaliwal.
He gave an example of monitoring near Balzac at which one industrial site was suspected, but after extensive monitoring the H2S turned out to be emanating from a stagnant water pond.
H2S gas can also come from sewers, sour gas wells, feedlots and stagnant water ponds. With the many wetland areas and feedlots in Wheatland County, more monitoring and time would be needed.
Readings on the 24-hour samples registered nothing over the three parts per billion levels. The VOC samples were also below detection criteria.
Dhaliwal said ambient air quality criteria are based on odour perception or nuisance factors, and not on detrimental health factors.
He presented council a study by Scott Simonton and Morgan Spears done in 2007, which pinpointed the need for a study of long-term effects of low-level exposure to H2S. The study stated current monitoring is inadequate, as even hand-held monitors can only register if emissions are over one part per million (ppm).
“However, if chronic toxicity for hydrogen sulphide exposure exists and is below one ppm, this equipment is obviously inadequate. Because other field methods for hydrogen sulfide gas are largely non-existent or are unwieldy, the question arises as to whether the odour threshold for hydrogen sulphide can be used to detect the gas at chronic exposure risk levels,” states Simonton.
The study further stated that limits normally apply to industrial monitoring, and monitoring for residential contamination of water tables is not done in rural areas. Impact on health has been noted at two ppm, to the most severe at 50 to 200 ppm. Simonton stated minor levels in home water supplies could be treated, and that smells of rotten egg develop up to 30 ppm and 30-100 ppm has a sweet smell, which becomes toxic to the nervous system.
“When analyzing the results of these studies, it is apparent that the low-level exposure toxicity from hydrogen sulphide gas is still unclear, with some studies showing no effect at two ppm and others showing toxic effects from concentrations several orders of magnitude lower,” stated Simonton in the study. “However, much of the data, as well as the recommendations from EPA, ATSDR and WHO, suggest toxicity from long-term exposure is likely to exist below the odour threshold. This suggests that an individual should not be exposed long term to any level of hydrogen sulphide that one can smell.”
Dhaliwal recommended that more monitoring could be done around the GFL plant and at designated sites. He said passive monitors could be placed that would give an average reading over a 30-day monitoring process. He recommended at least four monitors be used. The cost for a one-month period for two monitors is about $10,000.
CRAZ is a non-profit agency funded by private donations. Wheatland County had been approached in the past for funding support, but declined at the time.
CRAZ currently has only one mobile unit. If Wheatland County asks for simultaneous monitoring from two sites, CRAZ will locate another unit through its sources for.
Dhaliwal said hand-held monitors could be used onsite; however, samples could be too low for the devices to register anything. Council accepted his report as information.