Indoor and outdoor atmospheric ion mobility spectra, diurnal variation, and relationship with meteorological parameters

Abstract

We report measurements of small ion mobility spectra and concentrations made over a 5 month period using a Gerdien-type ion mobility spectrometer at one indoor site in central Bristol, UK, and one indoor and one outdoor site in a semirural area. We assess the diurnal variation in ion concentration and mobility, variability with meteorological parameters, and features within the ion mobility spectra. Ion concentration (typically in the range 100-1000 cm À3 ) was highest overnight and lowest in late morning and afternoon. Total conductivity also followed this trend suggesting that small ions contribute more to conductivity than larger charged particles, although at the semirural site, indoor activity produced charged aerosol intermittently, while infiltration of outdoor aerosol contributed at the urban site. Negative ion mobility (typically 1.6-1.9 cm 2 V À1 s À1 ) was higher overnight than at other times, while positive ion mobility (typically 1.2-1.4 cm 2 V À1 s À1 ) showed no diurnal variability. In general, temperature, pressure, wind speed, and water vapor pressure were inversely related to both concentration and mobility, except outdoors when (negative) mobility increased with increasing temperature and pressure, while increased relative humidity was associated with higher ion mobilities and concentrations. Analysis of high-resolution mobility spectra revealed several mobilities for each polarity at which peaks were identified across all sites, suggesting similarity in composition but with varying importance at each site. Intermediate ions (mobilities 0.2-0.3 cm 2 V À1 s À1 ) were observed at the outdoor site, but individual nucleation events which may be associated with them were not identifiable.

Aerosol hygroscopic growth and the dependence of atmospheric electric field measurements with relative humidity

“…Aerosols scavenge conducting atmospheric ions and reduce AEC such that, through Ohm's law (for a constant conduction current), an increase in the PG is observed (Retalis, 1977). It should be mentioned here that this is a simplistic view in the sense that the charge is still present, but is carried by larger and less mobile charged aerosols, which contributes much less to conductivity (Wright, Holden, Shallcross, & Henshaw, 2014). Besides, it is known that the ion-particle attachment coefficient (β) depends on the radius (R) of the particles (Gunn, 1954) as…”

Progress of negative air ions in health tourism environments applications

“…Natural low atmosphere, near to the Earth's surface, has average frequency production air ions (both positive and negative) about 10 ions/cm 3 /sec 26 . At where, small ions lifetime duration range 50 to 250 seconds, and indoor places near 30 seconds; while large ions can persist for several days 27 . During their existence, undergo a series of ion-molecule reactions and continuously identity changing 28 .…”

“…Some human activities capable to generate air ions: urban garden (blue/green space), wet sauna, water park, ionization place, artificial ionizers (corona discharges, thermionic electron emission from hot metal electrodes or photo-electrodes, radiation from radioisotopes, UV irradiation, high-pressure water injection, anion 33 incentive, tourmaline and other natural ores), dense urbanization atmosphere, pollution, suspended particles, power lines, industrial and vehicular emissions [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] .…”

“…In the urban and polluted environments, NAI concentrations may be reduced to less than 100 ions/cm 3 , due to the loss by anthropogenic aerosols attachment connections [27][28][29][30][31][32][33][34][35] . The atmosphere NAI enrichment can significantly oxidize volatile molecules, deodorising air, decrease or eliminate dust particles, fog, smoke, vehicle exhaust and reduce bacteria or pollen extract; by their aggregate and sediment on grounded surfaces potential [32][33][34] .…”

Atmospheric electricity as a proxy for air quality: Relationship between potential gradient and pollutant gases in an urban environment

“…is the mean electric mobility (the factor 2 is justified by the contribution of both positive and negative ions having similar mobilities) and is the electron charge. The influence of charged PM on atmospheric electric conductivity is neglected due to their relatively low mobility (Wright et al, 2014). Using (quasi-static) Ohm's law, it is possible to relate with !…”