A certified industrial hygienist must sign off on the plan. Activated carbon air filters are the highly recommended technology. Submissions are typically a few pages in length and include a facility diagram. Odor complaints are received by phone, e-mail or the city’s app. The city has a database to gather relevant information as well as track performance metrics. The department places daily complaints into a queue and has 24 hours to contact each complainant. If deemed necessary, the air inspector visits where the odor was observed, notes the wind direction , measures the odor intensity using a Nasal Ranger® and seeks out the source. Warehouse districts with multiple cultivation facilities are especially difficult due to odor overlap. The regulatory limit of 7:1 dilution is too high because at that level odors can still lead to nausea. The odor intensity scale can be tricky, since it is hard to define an intensity of 2 versus 4, for example. To standardize such qualitative scores, two inspectors travel together and measure odors together. In addition to air inspections and odor control plans, Colorado is conducting basic research on cannabis odors. Kaitlin Urso, an environmental protection specialist in the small business assistance program of the Colorado Department of Public Health and Environment,indoor vertical garden systems shared information on their study of cannabis volatile organic compound emissions. They look both at the terpenes emitted by the plants as well as the solvents used during extraction to infuse edibles.
The main concern is ozone formation caused by the VOCs, but information on odorants will also be generated. A similar study has already been performed . The air sampling in Colorado will be completed by September 2019.Texas is unique in its regulation of odors. It is the only state that uses “odor-based values” during the permitting and modeling process for new and expanded facilities. These values are curated from available literature and typically set at the odor detection threshold concentration . This is not a straightforward task because the published values can range over several orders of magnitude . Checking the values against actual air monitoring data and standards helps avoid levels that are known not to lead to odor complaints. Four odor experts in Australia were interviewed by phone in Sydney , Melbourne and Perth . In Australia, as in most of the world, odor impact assessments are typically based on air dispersion modelling; however, this approach is changing as some states to move the focus to environmental odor field assessments without modeling. There is also a move towards recognizing that all odors are not perceived the same – hedonic tone and intensity alter perception. Dr. Ruth Fisher and Dr. James Hayes, researchers with Dr. Richard Stuetz at the University of New South Wales, in Sydney, were contacted to gather the latest information on nuisance odor approaches. They pointed to the strengths of the programs in Victoria and Western Australia, which were contacted thereafter. Due to the large distances, transporting field samples to a panel in a laboratory cannot meet the 6-hour sample storage limit.
Attempts to use a field olfactometer yielded poor results, so other approaches have been developed. To prioritize odorants, a GC-sensory instrument with parallel GC-MS was used. When conducting investigations or community surveys, they advised against using the word “odor” and to instead ask about “things you don’t like” to gather unbiased responses. Community members have found the odor wheels intuitive and helpful. In Melbourne, Chris Bydder, an odor expert with Environment Protection Authority Victoria, provided his insights. The prior focus for odor regulation was on stack emission limits yet still led to complaints off-site because they missed fugitive emissions. The law was re-written to say “no offensive odor beyond boundary of premises.” Trained odor investigators are dispatched around-the-clock, any day of the week. Three calls regarding a new odor source trigger an investigation, or five calls for a known source. The investigative method is to confirm the presence of the odor, trace it to the source, and take action, if needed. Actions start with an abatement notice, progress to an infringement notice, and culminate with a fine of AUD $8,000, as appropriate. Typically, six complainants or more are required to take action. Inspectors are trained in dynamic plume assessment, which requires two inspectors. No public panels are used. Inspectors use a grid pattern, which is repeated on several days . Both the fenceline and upwind areas need to be canvassed. No attempt is made to identify the specific odorant that is the primary culprit. He warned against mixing field-dilution olfactometry data with laboratory dynamic dilution olfactometry data. The latter is in a controlled indoor environment with a larger set of panelists who are pre-screened. Even the Belgian 6-point intensity scale for “sniffing units” is more than his team needs.
They use three odor intensity scores: strong, weak and none.In Perth, Philippe Najean, an odor expert in Air Quality Services within the Department of Water and Environmental Regulation, shared his insights. Originally from France, he spoke with equal authority about the European and Western Australian approaches to environmental odors. The Western Australia odor guidance from 2002 is no longer used, and a draft 2018 update is under review . The new draft guidance no longer requires odor dispersion modeling because 10 years of data show that such an approach still leads to nuisance odor complaints. The prior criteria required substantial meteorological data, emission rates and limited the impact to 5 OU at 500 meters at the 98th percentile. Models simply are not good enough, yet many countries stick with them because they have become entrenched. The main challenge in an odor investigation is to ramp up the quality of information while ramping down the emotions. The first phase of an investigation is at the desk where information is gathered: odor description to identify potential sources, mapping and back-tracking the plume. The second phase is in the field if 5 or more complaints identify the same source. The third phase is to track the odor to the source using 3 levels of intensity , 3 levels of frequency and the duration. The VDI method 3940 Parts 2 and 3 that requires 5 standards for an intensity scale of 0-6 and paired inspectors was too complex and provided poor results. Similarly, lab and field olfactometry provided too variable results to be useful because dilution alters the “synergy” of the odor mixture. The GC-sensory method is a useful research tool but not for day-to-day field investigations. In addition to the phone interviews, a literature review revealed a summary of odor management across Australia and guidance from New South Wales . Many jurisdictions throughout the world have developed fact sheets and frequently asked questions to introduce the public and their own staff to the complexities of odor regulation and investigation. After providing introductory information on smell and the potential impacts of odors, the documents then tend to vary in degree of complexity. Some delve into technical topics such as dispersion modeling and odor thresholds ,plant drying rack while others present the steps to an odor investigation and how a complainant can gather useful information . Such material has been useful at the beginning of community meetings but does not take the place of interaction with authorities. Air inspectors find it sufficient to use their own sense of smell to verify odor complaints and try to respond to each call . Their familiarity with the local sources helps resolve most issues . Both field dilution measurements and laboratory panels did not aid investigations, nor did traditional dispersion modeling . The use of standardized odor descriptions may help inspectors , but agreeing with the complainant on the description is unnecessary. Masking odors to cover up malodors can magnify the problem . It is sometimes incorporated into guidance for complainants, too. The terms cover the main contributing factors or nuisance odors, namely frequency , intensity , duration , offensiveness , and location . FIDOL fails to capture, however, some of the more personal aspects of odor perception. The underlying mood and coping strategy of the complainant are missed, as is any connection or history with the offending source.
The person’s history and susceptibility to malodor effects – such as age, sex, and health – are not included, nor is past experience with the same or different odors, which can lead to sensitization or trigger memories. These factors, which serve as confounders to odor investigations, relate to properties inherent to odor yet not present for classical air pollutants . FIDOL also neglects the number of people impacted. The main weakness may be in the variability inherent in two of the factors: intensity and offensiveness.Jurisdictions tend to use the same database software to manage odor complaints as they do for any air pollution concern. Development is typically through software vendors but may be done in-hose if sufficient funds are available . Such data is valuable for tracking trends in odor complaints. More sophisticated evaluations than the number of complaints are needed, however, to capture the actual impacts. Software vendors also support facilities so they can manage complaints in-house and track their own data. Such systems are required in certain jurisdictions, such as Colorado. In addition to time trends, a complaints database can be analyzed statistically or visually. For drinking water, six utilities were included in a study of customer complaints . The data were evaluated using several statistical methods, and the same could be done for done for an odor complaint database. A combination of high frequency of complaints together with consistency of descriptors was indicative of episodic water quality problems. Another way of analyzing odor complaint data is through a “word cloud,” as was done for a chemical spill in a river . See Figure 2.3 for an example where the size of the font indicates word frequency.Some odorants are regulated by concentration limits at the fenceline of the source. Most odors, however, are mixtures of odorants, so regulations and standards have been developed to measure the dilution level required to reduce the total odor to non-detectable levels. This “pseudo-intensity” approach is the basis for predictive dispersion modeling and used, less frequently, as a component of nuisance odor investigations. Measurements of total odors are hampered by the intermittent nature of most sources and instrumentation. This often leaves the investigator with no option but to trust the complainant and try to verify the complaint using their own sense of smell. Repeated visits and upwind monitoring are common best practices. All jurisdictions face the challenge of reducing odors while at the same time allowing for industrial and urban development. Harmonization of efforts could lead to increasing ease and more affordable implementation . Increasing public concern over the impacts of odors, including on their health and property value, plus the advances in odor measurement technology are bound to lead to increased scrutiny and more stringent limits .The objective of this paper is to gather and review the technical approaches currently used to measure and monitor exposures to environmental odors. The technical approaches from around the world will be evaluated from a scientific standpoint as well as by applying practices from risk assessment, its framework and conventions, where appropriate. The goal is to identify best practices, identify any gaps and suggest how such gaps could be filled. The ultimate finding would be a universal approach that can be used for any odor complaint. This requires integrating disconnected research fields, not unlike the risk assessment of exposures to toxic chemicals has attempted. Investigations of nuisance odor complaints are the focus of this paper rather than predictive emission and dispersion modeling used to grant industrial facility permits. Some overlap between methods, however, exists.Odors are complex mixtures that evoke complex responses. There is no single parameter that completely characterizes the exposure to and impact of an odor . Unlike vision and hearing, the language of odor perception is poorly developed. Some people have a sense of smell that is orders-of-magnitude more sensitive than others, and the offensiveness of a smell is highly personal and culturally based. Even the microbes living in the nasal cavity can influence a person’s sense of smell . Such variability applies equally to air inspectors as it does to the general public.