The challenge

The atmosphere has a natural electric field which is caused by worldwide thunderstorm activity, but is present in all weather conditions. Atmospheric electric fields, typically 100 V/m in calm weather, are changed by both natural effects such as radioactivity, and manmade changes, like ions and aerosol particles created by traffic exhaust.

Investigating the electrical effects of traffic pollution has not been done before and is long overdue as the electrical effects of traffic pollution has implications for it's dispersion, human health and, through the sensitivity of insects to the electric field, animal welfare and pollination.

What we're doing

We are carrying out a field campaign in urban locations including roadside, parks and rooftop and will be measuring electric fields using field mills, aerosol concentration with optical particle counters alongside electrochemical carbon monoxide (CO) and volatile organic compound (VOC) measurements, to detect traffic emissions.

Novel radioactivity detectors (Aplin et al, 2017. Space Weather 15(5), 663) will be used to estimate the natural contribution to ion creation. Ions themselves and their sizes will be measured with a Programmable Ion Mobility spectrometer (PIMS, Aplin and Harrison 2001 Reviews of Scientific Instruments 72(8), 3467), specifically updated for this project.

Meteorological measurements will be taken citywide with existing weather stations, including the University of Bristol Chemistry building rooftop site. Particle number count at each site will be assessed using a condensation particle counter.

How it helps

These measurements, in combination with existing data from rural sites, will allow us to distinguish between natural and manmade (i.e. pollution) effects on the electrical environment and estimate the electrical significance of traffic pollution for the first time.

This project seeks to better understand how manmade pollutants are affecting the electrical environment, which will point to ways in which that environment can be protected. Air pollution is a topic of great public interest at present as particulates are known to be detrimental to human health. Human exposure to particulates depends on their dispersion but electrical charge on particles may affect that dispersion and therefore must be quantified to estimate exposure. Electrical charge on particles may affect exposure and dose due to changes in deposition within the mouth and lung.

Electroreception of bees is a groundbreaking topic, and understanding the electrical environment will require new techniques, such as those pioneered in this project. A changing electrostatic environment caused by traffic may be of importance to the local pollinator ecology. As bees are currently in decline within cities understanding their interaction with the electrical environment could be essential knowledge.