Aspergillus has both outdoor and indoor sources, including the air and water systems, and is closely associated with indoor fungal particle emissions, while Alternaria is much less so. This suggests that while Aspergillus is an integral member indoor aerobiome, Alternaria presence may be correlated with an increased outdoor contribution to indoor. We found that Alternaria was significantly correlated with open windows, suggesting that the association with increased bacterial diversity may be due to increased outdoor air contribution and not due to a co-association with Alternaria spores. Despite the quantification of these two fungal allergens, there is a huge amount of fungal diversity that was not sampled in this study. The direct measurement of fungal sequences through ITS sequences was not collected due to budgetary constraints, but is not only technically feasible but would be an excellent supplement to this data. This would allow for the examination of fungal diversity as it relates to the sampling factors presented in this study. Besides allergens, factors that could affect sampling, such as the distance from the bed of a participant, humidity, height above the floor, and temperature, did not impact the bacterial community recovered from participant bedrooms. Interestingly, humidity does, in contrast, affect the load of a number of different allergens. The fact that height above the floor does not impact microbial community confirms that there is enough mixing and averaging of the air properties over the 5-day sampling. In earlier studies, we have reported no significant variation in bacterial population diversity or abundance compared with filter sampling as a reference method. Therefore, there is no bias introduced by the fact that the capture efficiency measured with latex particles was 23%. Further, the 1-μm aerodynamic diameter chosen in this standardized reference method is aimed at being equivalent to Bacillus anthracis and surrogate Bacillus species,rolling grow benches demonstrating that our method is capable of capturing the microbial community.
In contrast to data presented here, O’Connor et al., who used vacuum cleaner dust collection for analysis of allergens and the microbiome, were able to obtain sufficient material for microbiome profiling in only 56% of their samples. By contrast, in this study with Inspirotec sampling of the air, we have collected sufficient material for 100% of the samples. In their population, they observed correlations between allergens from cockroach, mouse, cat, and dog and bacterial taxa that were significantly different between homes of asthmatic and non-asthmatic children. The population here was not selected by disease state, but all bedrooms were used by people with an allergy or asthma diagnosis. There were no significant differences in our dataset for allergens or microbiome based on self-reported symptoms, which likely is due to a lack of statistical power. We are not aware of any other study comparing allergen and microbiome content in the same samples. The inter-relation between the inhaled air of the aerobiome and the human airway microbiome and relation to human health is not well-understood. However, the method described here allows for a more thorough interrogation, due to its ability to recover the 1.2 μm and below particle size fraction. This fraction enters human airways, including particle sizes that are capable of deep penetration in the airways and triggering of asthma. This is likely to be more informative than measurements of vacuumed dust or settled dust. Additionally, the ease of deployment and running of the devices by the patients themselves, such as in this study, shows that it lends itself logistically to large-scale deployment and citizen-based science projects. This will be facilitated by cost savings through future manufacturing scale-up. Thus, we have demonstrated a robust, effective, and easy to use air sampling device that allows for a better understanding of the aerobiome.Legalization of cannabis production in 2017 has generated demands for state regulatory, research and extension agencies, including UC, to address the ecological, social and agricultural aspects of this crop, which has an estimated retail value of over $10 billion .
Despite its enormous value and importance to California’s agricultural economy, remarkably little is known about how the crop is cultivated. While general information exists on cannabis cultivation, such as plant density, growing conditions, and nutrient, pest and disease management , only a few studies have attempted to measure or characterize some more specific aspects of cannabis production, such as yield per plant and regional changes in total production area . These data represent only a very small fraction of domestic or global activity and are likely skewed since they were largely derived not from field studies but indirectly from police seizure data or aerial imagery . In California, where approximately 66% of U.S. marijuana is grown , knowledge of the specific practices across the wide range of conditions under which it is produced is almost nonexistent. Currently, 30 U.S. states have legalized cannabis production, sales and/or use, but strict regulations remain in place at the federal level, where it is classified as a Schedule I controlled substance. As a land-grant institution, UC receives federal support; were UC to engage in work that directly supports or enhances marijuana production or profitability, it would be inviolation of federal law and risk losing federal support. As a result, UC research on California cannabis production has been limited and focused on the geography of production and its environmental impacts . These studies have documented the negative effects of production on waterways, natural habitats and wildlife. While such effects are not unique to cannabis agriculture per se, they do present a significant threat to environmental quality and sensitive species in the watersheds where cannabis is grown . Science-based best management practices to mitigate or avoid impacts have not been developed for cannabis. Because information on cannabis production practices is so limited, it is currently not possible to identify key points of intervention to address the potential negative impacts of production. As a first step toward understanding cannabis production practices, we developed a statewide survey on cultivation techniques, pest and disease management, water use, labor and regulatory compliance.
The objective was to provide a starting point from which UC scientists could build research and extension programs that promote best management practices — which are allowable as long as their intended purpose is not to improve yields, quality or profitability. Survey results also establish a baseline for documenting changes in cultivation practices over time as legal cannabis production evolves in California. To characterize key aspects of cannabis production in California, we developed an anonymous online survey using Qualtrics survey software . A web-based survey that masked participants’ identity was determined to be the most suitable approach given that in-person interviews were limited by legal restrictions on UC researchers visiting cannabis farms, and mail or telephone surveys were constrained by the lack of any readily available mailing address or telephone contact information for most cannabis growers,curing weed who are understandably discrete with this information. Survey questions focused on operational features , pest and water management, labor, farm revenue and grower demographics. Two draft surveys were reviewed by a subset of cannabis growers to improve the relevance of the questions and terminology. A consistent critique was that the survey was too long and asked for too much detail, taking up to 2 hours to complete, and that such a large time commitment would significantly reduce the response. We therefore made the survey more concise by eliminating or rephrasing many detailed questions across various aspects of cannabis production. The final survey included 37 questions: 12 openended and 25 structured . Structured questions presented either a list of answer choices or a text box to fill in with a number. Each list of answer choices included an “Other” option with a box for growers to enter text. Open-ended questions had a text entry box with no character limit. Condensing the survey to capture more respondents resulted in less detailed data, but the overall nature of the survey remained the same — a survey to broadly characterize multiple aspects of cannabis production in California. Data from the survey has supported and contextualized research by other scientists on specific aspects of cannabis production, such as water use , permitting , law enforcement , testing requirements , crop prices and perceptions of cannabis cultivation in the broader community . Recruitment of survey participants leveraged networks of California cannabis growers who had organized themselves for various economic and political purposes . These were a combination of county, regional and large statewide organizations, with many growers affiliating with multiple groups. We identified the organizations through online searches and social media and sent recruitment emails to their membership list-serves. The emails contained an explanation of the survey goals, a link to the survey website and a message from the grower organization that endorsed the survey and encouraged members to participate. The emails were sent in July 2018 to approximately 17,500 email addresses, although not all members of these organizations necessarily cultivated cannabis, and the organizations noted that their mailing lists somewhat overlapped the lists of other groups that we contacted. For these reasons, the survey population was certainly less than 17,500 individual cannabis growers, but because we were not able to view mailing lists nor contact growers directly, and because there are no comprehensive surveys of the number of cannabis farms in California, we could not calculate a response rate or evaluate the representativeness of the sample.
Respondents were given until Aug. 15, 2018, to complete the survey. All survey participants remained anonymous, and response data did not include any specific participant identifiers. In total, 101 surveys were either partially or fully completed. Responses to open-ended questions were coded before summary. Since incomplete surveys were included in this summary, the number of responses varied between questions. Each response was considered a unique grower and farm operation. As noted, survey response rate was difficult to quantify, and participants were self-selecting, which introduces bias. The survey data should be taken only as a starting point to guide more detailed evaluations of specific practices in the future, not as a basis for developing recommendations for production practices or policies.Most growers reported groundwater as their primary water source for irrigation , with some growers reporting use of multiple water sources. Those using groundwater extracted 87% of annual volume between June and October. Of those storing water, most stored exclusively well or spring water, though some stored municipal water or rainwater . Extraction to storage was greatest in summer but was relatively well distributed throughout the year. Many growers reported that adding storage was either cost prohibitive or limited by regulatory constraints. Half the respondents indicated that additional storage was not needed, 40% indicated that the high costs of building storage were limiting, and 5% reported there was insufficient water available and 5% that they were unable to obtain permits to store . Most growers reported using variable amounts of water across the growing season. Outdoor growers applied, on average, 5.5 gal per day per plant in August and 5.1 gal per day per plant in September. Greenhouse growers applied an average of 2.5 gal per day per plant in August and 2.8 gal per day per plant in September . When standardized by area, application rates were very similar between cultivation types . In our survey, growers reported using low maximum pumping rates : 53% indicated rates ranging 1 to 50 gal per minute, 7% did not know their pumping rate and the remaining 40%, who used groundwater or municipal water sources, indicated that this question did not apply to them. Growers reported 14 different arthropods, 13 diseases and nine vertebrates that had negative impacts on cannabis production . The most frequent arthropod pest was mites , followed by thrips , aphids and unknown larvae . The most common vertebrate pests were gophers, mice and rats , followed by deer and wild boars . Powdery mildew was by far the most commonly reported disease , followed by other fungal diseases such as molds and rots . While these findings are in line with cannabis pests and diseases reported by others , survey data are self-reported data and grower identification of pests and diseases may not be entirely accurate. For instance, the complex of mites reported included russet mites, spider mites, broad mites and red mites.