Development of the first global standard for airborne microplastic monitoring.

Microplastics (MPs) have been found in virtually all environments: soil, living things, water and air. The past five years have included a small number of investigations over long time scales (up to a year for some) and across wide ranging locations. One common finding is that MP numbers and types vary greatly in different environments. There is now concern regarding the possible impacts of MPs in terms of public and other organism health. MPs are of the size range range of 1 micron to 5 mm, which ranges from the size of a small bacterium to a sesame seed at most, inhalable, and common in food chains/diet. They come in different shapes and polymer types, depending on the plastics that are derived from eg. polyester or polypropylene, which are common in textiles or packaging. Recently, they have been identified inside people's lungs, blood and bowels, and questions arise as to whether they cause or exacerbate lung or bowel conditions like chronic cough or irritable bowel disease. In marine organisms they are also associated with growth and inflammation type impacts. Current air quality measures and monitoring completely overlook this contaminant type, which is likely to become a public health issue. Current measurements of the types of particles and gases in routine air monitoring also fail to completely explain high levels of specific cough and inflammation type disease incidences in many cities. This study firstly aims to establish a means to measure MPs in the air, which would represent a new air quality measure methodology. The approach we suggest 'slip streams' the current pollen monitoring methods available worldwide, making it accessible for those who do not have access to specialist and expensive equipment. The method proposed does however have certain robust elements included and these are to ensure that the agencies who conduct air quality measurements can use the data produced.
The second aspect of this work is to develop an automated identification and counting technology approach so that the monitoring can be completed in future using low cost, non-specialist equipment and expertise. Ideally, the method will be available for reliable and reproducible use around the world. This will be achieved by a combination of manipulation of existing available datasets on MPs found in the air (from our past three years of studies), and trials with colleagues located across four continents who work with different pollen sampling approaches. One novel approach we will use will be to make a set of MP 'reference strips' that can be posted to users and used an as internal calibration when taking images for analysis. There are parallels between established pollen monitoring and trying to set up something similar for MPs, that we can exploit. Pollen come in a comparable range of shapes and sizes (ranging from 5-100+ microns) to MPs. They are a trigger for health impacts and, as such, are routinely and robustly monitored such that datasets can be shared and compared internationally as well as communicated to the public. The same parameters can apply for MPs. The second aspect, the auto-identification and counting would represent a significant step forward for both pollen and MP monitoring, that could see wider benefits still. The trials we conduct will run in parallel with the current practice for MP sampling, to add further cross comparison but also to anchor any new approach to what is currently deemed as acceptable in the wider community of research scientists working in this area.