Alberta Health Odours and Human Health Public Health and Compliance February 2017 (This page intentionally left blank.) About this document: This literature review was prepared to inventory and summarize scientific information about the relationship between odour and human health. The intended audience for this report is primarily health professionals or other professionals with related scientific backgrounds, but information is contained in this report that may also be relevant to interested members of the public. The information in this document is provided on an informative and summative basis only. Recognizing that the topics addressed in this report are areas of current scientific inquiry, users of this report are encouraged to review the latest literature in the field of odour science. Development of the Clean Air Strategic Alliance’s “Good Practices Guide for Odour Management in Alberta” (ISBN 978-1-896250-81-6; available at www.casahome.org) was informed by this document. This document may be cited as follows: Government of Alberta. (2017). Odours and Human Health. Environmental Public Health Science Unit, Health Protection Branch, Public Health and Compliance Division, Alberta Health. Edmonton, Alberta. Statement of Availability: As part of the Government of Alberta’s commitment to open government, this publication is posted to and permanently retained in the Open Government Portal at http://open.alberta.ca/publications/9781460131534 . Print copies are also available. ISBN: 978-1-4601-3153-4 (PDF) ISBN: 978-1-4601-3152-7 (Print) Copyright and Licence: © Her Majesty the Queen in Right of Alberta, as represented by the Minister of Alberta Health, 2017 This document is made available under the Open Government Licence – Alberta (http://open.alberta.ca/licence). Every effort has been made to provide proper acknowledgement of original sources. If cases are identified where this has not been done, please notify Alberta Health so appropriate corrective action can be taken. For more information, please contact: Health Protection Branch Public Health and Compliance Alberta Health 23rd Floor, ATB Place North 10025 Jasper Avenue NW Edmonton, Alberta, T5J 1S6 Canada Facsimile: 780-427-1470 Telephone: 780-427-4518 in Edmonton or to be connected toll-free inside Alberta, dial 310-0000 Email: [email protected] Alberta Health, Health Protection Branch Odours and Human Health February 2017 Executive Summary The effect of odours on health is a recognized environmental issue. Many people, particularly residents living near odour-emitting facilities such as concentrated animal feeding operations, have expressed concerns and questions regarding the physical and psychological health impacts of exposures to environmental odours. An abundance of research has been done in this topic over the last 30 years; however, there remains much debate over the impacts of odours on health, the mechanisms in which odours induce a health response, and the most effective risk-based approaches for regulating health impacts from exposures. This report explores and summarizes the findings from over 500 peer-reviewed epidemiology and experimental studies assessing odour and health outcomes in humans. The primary objectives are to: 1. present a collection of scientific literature pertaining to odour-induced health responses in humans; 2. provide a summary of the current state-of knowledge regarding odours and health; and 3. evaluate the factors and mechanisms involved in odour-induced responses. The main outcomes of interest include health symptoms, physiological responses, annoyance, mood and psychological health, quality of life, cognition (task performance), athletic performance, and brain activity. Epidemiological Studies Odours from a variety of sources (petrochemical plants, pulp mills, sewage/waste treatment plants, fertilizer plants, pig-rearing facilities) have been found to correlate with frequency and intensity of odour annoyance. Degree of annoyance was generally lowest with pleasant odours and highest with unpleasant odours, indicating a role for odour pleasantness in odour-induced annoyance. Residents of communities located near odour-emitting facilities generally report a higher number of health symptoms compared to residents of control communities. Reported symptoms included, for example, cough, nausea, congestion, eye irritation, headache, dizziness, sleep problems, diarrhea, chest pain, and respiratory symptoms. Self-reported frequency of odour perception (a subjective measure of exposure) often correlated with symptoms, while residence distance to facility (an objective measure of exposure) typically did not. The use of subjective measures of exposure is a potential source of reporting bias and results should be interpreted with caution. The relationship between odour exposure and health symptoms also appears to be influenced by odour pleasantness. Exposure to unpleasant odours, such as those from a pig facility, a fat refinery, or a cast-iron factory, results in more symptom reporting than exposure to moderate or pleasant odours. A consistent finding among the epidemiology studies is that symptom reporting is mediated by odour annoyance. Many studies have found odour annoyance to be a stronger predictor of symptom © Her Majesty the Queen in Right of Alberta, as represented by the Minister of Alberta Health, 2017 Page i Alberta Health, Health Protection Branch Odours and Human Health February 2017 reporting than odour perception, odour concentration, and residence distance to facility. The relationship between odour annoyance and symptom reporting may also be influenced by individual or community attitudes towards an odour, method of coping with an odour, environmental worry, and perceiving odour as a threat to health. Experimental Studies - Physiological Responses, Mood, and Task Performance Experimental findings demonstrate that odours can significantly impact physiological outcomes, irritant symptoms, mood, and cognition (task performance); however, this is not true for all odours in all situations. Responses appear to be odorant-specific and are also heavily influenced by individual factors and experimental methods. Odours were found to significantly influence physiological arousal parameters (heart rate, blood pressure, respiratory rate, skin conductance) and reporting of irritant symptoms (headaches, eye irritation, nausea, dry eye) in several studies. However, contradictory or null findings to these results were also found. For studies of odour and mood, pleasant odours tended to induce more positive moods (mainly increased happiness and improved overall mood) and unpleasant odours tended to induce more negative moods (mainly decreased overall mood or increased anger and disgust). Due to the variation in responses, any further conclusions beyond this basic finding were difficult to identify. A common finding among the studies evaluating physiological outcomes, symptoms, and mood is that odour-induced responses are impacted by individual cognitive attitudes towards an odour. Subjects given a harmful bias towards an odour were more likely to report irritant symptoms than those given a healthful bias. Similarly, subjects given a healthful bias towards tend to be in a more pleasant mood than those given a harmful bias. Varied results have been found with studies assessing odours and cognition function (task performance). Both pleasant and unpleasant odours were shown to improve or impair performance on memory and recognition tasks, math tasks, lexical tasks (word recognition, word decoding), and motor reaction tasks. Other studies have demonstrated no effect of odours on task performance. This lack of consistency across studies suggests that the impact of odours on task performance may be odorant-specific, as well as influenced by individual factors. The relationship between odours and physiological or psychological health is extremely complex and influenced by a wide variety of odour characteristics (e.g., hedonicity, familiarity) and individual factors (e.g., subjective expectations, personal experience with an odour). Different odours induce different responses, and odours appear to have their own cognitive and mood profiles. © Her Majesty the Queen in Right of Alberta, as represented by the Minister of Alberta Health, 2017 Page ii Alberta Health, Health Protection Branch Odours and Human Health February 2017 Experimental Studies - Brain Responses In studies localizing odour-induced brain activity, more than 30 different regions have been indicated as being involved in some aspect of olfaction. The pattern of brain activity can be influenced by factors such as odour characteristics (e.g., intensity, pleasantness), the task at-hand (e.g., paying attention to an odour, odour identification), subjective association with an odour (e.g., familiarity, emotional association), and pre-conceived expectations about an odour. Different studies show varied brain responses following exposure to pleasant and unpleasant odours. The lack of consistency across studies makes it extremely difficult to draw any definitive conclusions regarding how pleasant or unpleasant odours affect the brain. There are a complex array of factors involved in the response to odour pleasantness, such as type of odour (e.g., food vs floral), familiarity, and situational context. The orbitofrontal cortex and the amygdala are two brain regions often found to be activated by both pleasant and unpleasant odours, and are considered to play a strong role in emotional processing.