The trap is equipped with a slit for air intake. The air is suctioned by a motor and intercepted by a rotating drum fitted with a belt made of Melinex, coated with adhesivesilicone.The tape is cut into daily segments weekly and mounted on slides with glycerogelatin and fuchsin, protected with coverslips and, after a rest period,observed under an optical microscope for analysis. In this study,four longitudinal transects were read with an immersion 50× optical zoom lens. The surface area read was more than 10% of the total sampling area, allowing us to identify the different pollen types and carry out the corresponding count .The Cannabis pollen grain is a medium-sized monad, 20–30 μ min diameter,spheroidal, isopolar and trizonoporate. The pores have an annulus,and the in tine forms an oncus under the pore. Under an optical microscope,the ornamentation of the exine is psilate . Data on days with an intrusion of African air masses in Spain have been obtained from the Spanish Ministry of Ecological Transition and Demographic Challenge.
Information about African dust out breaks reaching the Iberian Peninsula is relevant to associate African Cannabis pollen with northwards air masses from Africa.The methodology used to identify these episodes is available in the document “Establishing guidelines for the demonstration and subtraction of exceedances attributable to natural sources under Directive 2008/50/ECon ambient air quality and cleaner air for Europe” . Daily meteorological situations were identified, cannabis grow system and air mass back trajectories were obtained with HYSPLIT. The results were then validated by studying the synoptic maps of the European Centre for Medium-Range Weather Forecasts, Aerosol Index Maps reflecting the Ozone Monitoring Instrument indirect measurement and daily results from SKIRON, the Barcelona Supercomputing Centre and the Navy Aerosol Analysis and Prediction System .This work has used MITECO reports available from 2009 to 2020. For the period 2004 to 2008, the African dust intrusion data were taken from Negral Álvarez , and for the years 2002 and 2003, the NAAPs aerosol maps were consulted. No NAAPs maps were available for 1999, so the arrival of African dust intrusions was estimated using the back trajectories obtained with HYSPLIT. The presence of Cannabis pollen in the bioaerosol of the Region of Murcia was sporadic until 2017.
Up to that time, it was considered aminority pollen type in our region and was not a part of the pollen calendar. Although up to 21 pollen grains/m3 could be found in the air of Cartagena before 2017, almost half of it was collected on a single day, and its presence was concentrated on specific days. As an example, the peak day in 2002, 04/26/2002, was of local/regional origin . However, we have verified that since2017, a systematic count that could be due to autochthonous flowering has occurred in Cartagena, Murcia and Lorca. This asseveration is supported by the dismantling of illegal Cannabis crops in the Region of Murcia over the last five years. Alvarez et al. warned about changes in Cannabis consumption in Spain, marijuana grow system where “the rise of large-scale Cannabis plantations in the Spanish Mediterranean coast has been increasingly replacing Moroccan hashish imports.” Likewise, the expansion of small scale cultivation in Spain is assumed to be taken place . In this context, the control of Cannabis pollen broadens the scope of Aerobiology with a new application for public health/law professionals. These professionals could be interested in the Cannabis MPS. Depending on the year, it can start at any time from the beginning to the end of June and last until the first days of August or even September, with a variation of13 days in Cartagena, 16 days in Murcia and 32 days in Lorca . Althoug hour MPS is not the standard definition in which 95% of the population is retained, discarding the 5% at the tails , Jato et al. argued that the MPS should be defined according to the purpose of the research.
The purpose of our research was to identify the origin of the Cannabis pollen grains, regardless of the concentrations. Nevertheless, the option to work with the standard MPS was assessed. This idea was discarded because it would mean leaving out high concentration days,even the peak day, e.g., in Lorca in 2018. This behaviour is not expected for plants spread naturally in the area of study.The duration of the MPS in the Region of Murcia is much shorter than that defined for areas where there is widespread cultivation of this plant,like Tetouan. There, the duration of the MPS is in the range of 127to 172 days, and it constitutes a major pollen type. In Islamabad, Pakistan, it is the most important allergen from July to September .The concentrations registered in the three cities of the Region of Murcia increased from 2017 to 2020, with differences among the mean values and a positive trend in the evolution of the AP In . In terms of the consequences for allergy sufferers, the AP In was probably not high enough to cause problems for the general population during the years of the study.