Rohan Jayaratne's research while affiliated with Queensland University of Technology and other places
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Publications (75)
Epidemiological studies investigating the association between daily particle exposure and health effects are frequently based on a single monitoring site located in an urban background. Using a central site in epidemiological time-series studies has been established based on the premises of low spatial variability of particles within the areas of i...
Motor vehicle emissions are the primary air pollution source in cities worldwide. Changes in traffic flow in a city can drastically change overall levels of air pollution. The level of air pollution may vary significantly in some street segments compared to others, and a small number of stationary ambient air pollution monitors may not capture this...
Air pollution is among the top risk faced by people around the world, and therefore combating it is among the top priorities. It begins with identifying the sources that contribute the most to local air pollution to prioritize their control. There are advanced methods for source identification and apportionment, but such methods are not available i...
Evidence of associations between exposure to ambient air pollution and health outcomes are sparse in the South Asian region due to limited air pollution exposure and quality health data. This study investigated the potential impacts of ambient particulate matter (PM) on respiratory disease hospitalization in Kandy, Sri Lanka for the year 2019. The...
Urban air pollution is a significant health risks to urban dwellers around the world. Knowledge of the levels of air pollution at various spatial locations in a city offers insight into the personal exposure of residents and facilitates the control of air pollution. This study investigated ultrafine particles (UFP) in key microenvironments in which...
The COVID-19 pandemic has led to the complete lockdown of many cities worldwide. Lockdowns have significantly changed human behaviour, such as fewer or no industrial activities and limited road and air transport, affecting the environment. In this study, we aimed to assess the variability and trends of PM2.5 (mass concentration of airborne particul...
The diurnal variation of pollutants such as particles and carbon monoxide (CO) in urban environments typically follow the traffic density, with two peaks coinciding with the weekday morning and evening rush-hour periods. However, observations made in central Brisbane, the third largest city in Australia, demonstrated an anomalous diurnal variation...
This report provides a comprehensive update on the use and operation of low-cost sensing devices for assessing atmosphere chemical composition. The original report, published by WMO in 2018, was fully revised to update new scholarly understanding of low-cost sensors (LCS) that was published in the peer-reviewed literature.
While some of the origin...
Concerns about air quality were expressed in preparations for the Commonwealth Games (Games), which were held at the Gold Coast, Australia, from 4th to 15th April, 2018, an international sporting event attended by more than 6600 athletes and over 670,000 visitors. Our aim was to trial application of low-cost sensors by conducting high spatial resol...
As the environmental awareness of urban citizens increases, traditional air quality monitoring stations cannot satisfy the need for air quality data at high temporal and spatial resolution due to their high construction and maintenance costs. Low-cost air quality monitors are being increasingly used for this purpose because of their portability and...
Low-cost air quality sensors are increasingly being used in many applications; however, many of their performance characteristics have not been adequately investigated. This study was conducted over a period of 13 months using low-cost air quality monitors, each comprising two low-cost sensors, which were subjected to a wide range of pollution sour...
Shanghai, a metropolitan city in China, has suffered from severe air pollution, especially PM2.5, in the last few years. Up to now the contribution of local emission and regional transport to the formation of haze in Shanghai remains unclear. With an aim to characterize the mechanism of haze formation in Shanghai, the present paper attempted to pro...
Exposure to air pollution is a significant health risk, and children who are exposed to it are likely to have lifelong consequences. Ultrafine particles (UFPs) are emitted by all combustion sources, and can be used as a proxy for the presence of combustion products. The present study, the first of its kind to be conducted in Africa, assessed school...
Air pollution in urban areas is a major global public health issue. Very little work has been done to monitor the ambient air pollution in Sri Lanka's cities. Spot measurements have indicated that the pollution levels in Colombo are well above the standard levels recommended by the World Health Organization. The aim of this study is to continuously...
While low-cost particle sensors are increasingly being used in numerous applications, most of them have no heater or dryer at the inlet to remove water from the sample before measurement. Deliquescent growth of particles and the formation of fog droplets in the atmosphere can lead to significant increases in particle number concentration (PNC) and...
Small aerosols at a given location in the atmosphere often originate in situ
from new particle formation (NPF). However, they can also be produced and
then transported from a distant location to the point of observation where
they may continue to grow to larger sizes. This study was carried out in the
subtropical urban environment of Brisbane, Aust...
New particle formation (NPF) is a common occurrence in urban environments where it is promoted by a ready supply of gaseous precursors such as sulfuric acid, ammonium and volatile organic compounds originating mainly from motor vehicle emissions. In this paper, we investigate the influence of wind speed on the occurrence of NPF events in a subtropi...
While low-cost particle sensors are being increasingly used in numerous applications, most of them have no heater or dryer at the inlet to remove water from the sample before measurement. Deliquescent growth of particles and the formation of fog droplets in the atmosphere can lead to significant increases in particle number concentration (PNC) and...
Small aerosols at a given location in the atmosphere often originate in-situ from new particle formation (NPF). However, they can also be produced and then transported from a distant location to the point of observation where they may continue to grow to larger sizes. This study was carried out in the subtropical urban environment of Brisbane, Aust...
Technical characteristics of the phone according to the manufacturer's data sheets [24].
(DOCX)
Photograph showing BROAD Life mobile phone interfaces.
The left photo shows the smart phone mode and the right photo shows the air quality mode.
(TIF)
Mobile phones have a large spectrum of applications, aiding in risk prevention and improving health and wellbeing of their owners. So far, however, they have not been used for direct assessment of personal exposure to air pollution. In this study, we comprehensively evaluated the first, and the only available, mobile phone—BROAD Life—equipped with...
Experimental setup to investigate the mobile phones’ response to formaldehyde.
(TIF)
Scatter plots of the phones versus OPC for particles of sizes 2.5 μm for the phones, and 2.1 μm for the OPC.
(TIF)
Scatter plot of PM2.5 concentrations of phones versus DustTrak showing linear relationship between the phones and the DustTrak for cigarette smoke particles.
(TIF)
Scatter plot of formaldehyde analyzer and mobile phones.
(TIF)
To date, few comprehensive field observations of new particle
formation (NPF) have been carried out at mountaintop sites in China. In this
study, simultaneous measurements of particle size distribution, trace gases, meteorological parameters, and mass concentration and chemical composition of
PM2.5 were performed at the summit of Mt. Tai (1534 m a....
Studying the characteristics of new particle formation (NPF) is important as it is generally recognized as a major contributor to particle pollution in urban environments. We investigated NPF events that occurred during a 1-year period in the urban environment of Brisbane, Australia, using a neutral cluster and air ion spectrometer (NAIS) which is...
New particle formation (NPF) has been observed in many highly
polluted environments of South East Asia, including Beijing, where
the extent of its contribution to intense haze events is still an
open question. Estimated characteristics of NPF events, such as
their starting times and formation and growth rates of particles,
are more accurate when th...
New particle formation (NPF) has been observed in many highly polluted environments of South-East Asia, including Beijing, where the extent of its contribution to intense haze events is still an open question. Estimated characteristics of NPF events, such as their starting times and formation and growth rates of particles, are very different when t...
To date very few field observations of new particle formation (NPF) have been carried out at the high-elevation mountain sites in China. Simultaneously measurements of particle size distributions, gas species, meteorological conditions and PM2.5 were performed at the summit of Mt. Tai (1530 m ASL) from 25 July to 24 October 2014 (І), 21 September t...
Aerosol particles form from molecular clusters at a size of about 1.6 nm. Conventional aerosol measuring instruments such as the scanning mobility particle sizer (SMPS) cannot monitor particles smaller than about 5 nm. The neutral cluster and air ion spectrometer (NAIS) is a recently developed instrument that is designed to measure airborne ions an...
There is considerable scientific interest in personal exposure to ultrafine particles. Owing to their small size, these particles are able to penetrate deep into the lungs, where they may cause adverse respiratory, pulmonary and cardiovascular health effects. This article presents Bayesian hierarchical models for estimating and comparing inhaled pa...
Data gathered from the US National Lightning Detection Network (TM) (NLDN) show that the peak currents of lightning flashes striking the sea are significantly higher than those of lightning flashes striking the land. We suggest that the unfavorable conditions for the formation of positive charge pockets in maritime clouds lead to lightning initiati...
The charge and chemical composition of ambient particles in an urban environment were determined using a Neutral Particle and Air Ion Spectrometer and an Aerodyne compact Time-Of-Flight Aerosol Mass Spectrometer. Particle formation and growth events were observed on 20 of the 36 days of sampling, with eight of these events classified as strong. Dur...
The surface area of inhaled particles deposited in the alveolar region, as reported by the TSI nanoparticle surface area monitor (NSAM), was compared with the corresponding value estimated by a TSI scanning mobility particle sizer (SMPS) for a range of environmentally relevant aerosols, including petrol emissions, ETS, laser printer emissions, cook...
There has been considerable scientific interest in personal exposure to ultrafine particles (UFP). In this study, the inhaled particle surface area doses and dose relative intensities in the tracheobronchial and alveolar regions of lungs were calculated using measured 24-hour UFP time series of school children personal exposures. Bayesian hierarchi...
Ions play an important role in affecting climate and particle formation
in the atmosphere. Small ions rapidly attach to particles in the air
and, therefore, studies have shown that they are suppressed in polluted
environments. Urban environments, in particular, are dominated by motor
vehicle emissions and, since motor vehicles are a source of both...
Background:
Bicycle commuting in an urban environment of high air pollution is known to be a potential health risk, especially for susceptible individuals. While risk management strategies aimed to reduce exposure to motorised traffic emissions have been suggested, only limited studies have assessed the utility of such strategies in real-world cir...
Frequent exposure to ultrafine particles (UFP) is associated with detrimental effects on cardiopulmonary function and health. UFP dose and therefore the associated health risk are a factor of exposure frequency, duration, and magnitude of (therefore also proximity to) a UFP emission source. Bicycle commuters using on-road routes during peak traffic...
While recent research has provided valuable information as to the composition of laser printer particles, their formation mechanisms, and explained why some printers are emitters while others are low emitters, questions relating to the potential exposure of office workers remained unanswered. In particular, (i) what impact does the operation of las...
A composite line source emission (CLSE) model was developed to specifically quantify exposure levels and describe the spatial variability of vehicle emissions in traffic interrupted microenvironments. This model took into account the complexity of vehicle movements in the queue, as well as different emission rates relevant to various driving condit...
Atmospheric ions are produced by many natural and anthropogenic sources and their concentrations vary widely between different environments. There is very little information on their concentrations in different types of urban environments, how they compare across these environments and their dominant sources. In this study, we measured airborne con...
Recently published studies not only demonstrated that laser printers are often significant sources of ultrafine particles, but they also shed light on particle formation mechanisms. While the role of fuser roller temperature as a factor affecting particle formation rate has been postulated, its impact has never been quantified. To address this gap...
Along with their essential role in electricity transmission and distribution, some powerlines also generate large concentrations of corona ions. This study aimed at the comprehensive investigation of corona ions, vertical direct current electric field (dc e-field), ambient aerosol particle charge, and particle number concentration levels in the pro...
We assess the increase in particle number emissions from motor vehicles driving at steady speed when forced to stop and accelerate from rest. Considering the example of a signalized pedestrian crossing on a two-way single-lane urban road, we use a complex line source method to calculate the total emissions produced by a specific number and mix of l...
Urban motor vehicle fleets are a major source of particulate matter pollution, especially of ultrafine particles (diameters < 0.1 microm), and exposure to particulate matter has known serious health effects. A considerable body of literature is available on vehicle particle emission factors derived using a wide range of different measurement method...
While current research has demonstrated that the operation of some laser printers results in emission of high concentrations of ultrafine particles, fundamental gaps in knowledge in relation to the emissions still remain. In particular, there have been no answers provided to questions such as the following: (1) What is the composition of the partic...
The charge on ambient atmospheric particles is an important parameter in the investigation of particle dynamics. Yet, there is only limited knowledge available on it, mainly due to the lack of instrumentation for its direct measurement. The aim of this study was to explore the application and suitability of the Aerosol Electrometer (AE) TSI Model 3...
In this paper we attempt to show that the necessary condition to create a lightning ground flash is the generation of a vertical conducting channel below the main negative charge centre. The probability of such an event increases if frequent breakdown takes place between the negative charge centre and the lower positive charge centre (LPCC). Analys...
Particle number, NOx and CO concentrations were measured simultaneously at the air entry portal and at the mid-point of a 511m bi-directional road tunnel, used entirely by urban public transport buses. The aim of this study was to provide information on concentrations of these pollutants inside a unique bus tunnel, and to develop a viable methodolo...
The aim of this work was to review and synthesize the existing knowledge on ultrafine particles in the air with a specific focus on those originating due to vehicles emissions. This constitutes Part II of a literature review on ultrafine (UF) particles, with industrial and power plant emissions covered in Part I. As the first step, the review consi...
Presence of high concentrations of corona ions in any air environment cause changes in the earth’s natural dc e-field; while their interaction with airborne aerosols produce charged particles. The charged particles and ions are dispersed by wind, and depending on the prevailing meteorology, their presence can be observed several hundreds of meters...
In this paper, we have analysed the particle number and CO2 concentration data from four previous dynamometer studies, each consisting of a number of heavy-duty vehicles of different age and operating on different diesel fuel blends. Emission rates were calculated for four operational modes corresponding to 0%, 25%, 50% and 100% of the maximum rate...
A comprehensive study of the particle and carbon dioxide emissions from a fleet of six dedicated liquefied petroleum gas
(LPG) powered and five unleaded petrol (ULP) powered new Ford Falcon Forte passenger vehicles was carried out on a
chassis dynamometer at four different vehicle speeds—0 (idle), 40, 60, 80 and 100 km h1. Emission factors and thei...
A method of deriving lightning ground flash density from CIGRE lightning flash counter registrations based on the detection efficiency of the instrument, independent of the latitudinal variation of cloud flash-to-ground flash ratio is presented. Using this method, the annual mean ground flash densities, Ng, over a period of up to 22 years were reca...
Air pollution levels were monitored continuously over a period of 4 weeks at four sampling sites along a busy urban corridor in Brisbane. The selected sites were representative of industrial and residential types of urban environment affected by vehicular traffic emissions. The concentration levels of submicrometer particle number, PM 2.5 , PM 10 ,...
Corona ions are generated during electrical discharges which may occur around high voltage infrastructures such as powerlines and substations (Abdel-Salam et al. 2001). Interactions between these emitted ions and airborne aerosols produce charged particles, which are carried to in the wind and depending on the prevailing meteorological conditions,...
Due to the potential effects of vehicle emissions on human health, the ability to predict
ultrafine particle number concentration and dispersion is important for maintaining a healthy environment and evaluating human exposure. This study aimed to investigate the
concentration and distribution of airborne particles at a bus station, with the buses i...
Particle emissions from twelve buses, aged 1 to 19 years, operating alternatively on low sulphur (LS; 500 ppm) and ultra-low sulphur (ULS; 50 ppm) diesel fuel were monitored at four steady-state operating modes on a chassis dynamometer. The mean particle number emission rate using ULS diesel was lower than the rate using LS diesel in each of the fo...
Recent studies have shown that the operation of laser printers can result in the emission of high concentrations of ultrafine particles. However, fundamental gaps in knowledge still remain, for example, it is not clear what makes a printer a high emitter or why some models alternate between being low and high emitters. In order to provide insight i...
It is now well known that the operation of some laser printers results in the emission of high concentrations of ultrafine particles. A significant fraction of these particles lie in the nanometre size range and the health effects of these particles are still largely unknown. In this respect, understanding the process of particle formation is impor...
Particle number concentrations vary significantly with environment and, in this study, we attempt to assess the significance of these differences. Towards this aim, we reviewed 85 papers that have reported particle number concentrations levels at 126 sites covering different environments. We grouped the results into eight categories according to me...
The aim of this work was to review the existing instrumental methods to monitor airborne nanoparticle in different types of indoor and outdoor environments in order to detect their presence and to characterise their properties. Firstly the terminology and definitions used in this field are discussed, which is followed by a review of the methods to...
Citations
... The relatively low average value of the PM 2.5 /CO ratio (0.014 ± 0.008) indicated relatively low contributions of secondary aerosols to PM 2.5 concentrations in Tehran. Xiu et al. (2022) proposed the CO/PM 2.5 ratio as a novel signature to identify combustion-generated pollution sources. During 2015/2021, the seasonal averages of CO/PM 2.5 in spring, summer, autumn, and winter in Tehran were 95.1 ± 50.4, ...
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... Твердые частицы (ТЧ) в настоящее время рассматриваются как крайне опасный загрязнитель воздуха, который способен вызывать ряд проблем со здоровьем у населения. Сообщается, что ТЧ способны про-никать глубоко в дыхательную систему и вызывать там хронические воспалительные процессы [1,2]. Также известно, что данные частицы из-за своего размера могут попадать в кровеносную систему и вы- УСПЕХИ СОВРЕМЕННОГО ЕСТЕСТВОЗНАНИЯ № 2, 2023 ГЕОЛОГО-МИНЕРАЛОГИЧЕСКИЕ НАУКИ (1.6.3, 1.6.5, 1.6.6, ...
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... KOALA is a low-cost small air quality sensor unit developed by the Queensland University of Technology, Australia. The KOALA sensors unit have already been tested against standard air quality instruments ) and successfully used in previous research on air pollution in several countries , including in Sri Lanka (Priyankara et al. 2021;Senarathna et al. 2021). ...
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... As already reported in the literature, data from LCSs do not meet the quality objectives for use in regulatory observations stated for instance by the associate EU directive (Peltier et al., 2020;Directive 2008/50/EC, 2008. A key question, however, 355 is whether they can still be used to provide indicative measurements, which require less accuracy and can complement the regulatory observations by increasing the spatiotemporal resolution of AQ measurements. ...
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... Recent advancements in low-cost particulate matter (PM) sensors led to their extensive use in various applications, such as air quality (AQ) in indoor environments [39][40][41][42][43] and outdoor [44][45][46][47] , including large-scale deployments [48][49][50] by academic researchers and citizen scientists. Optical PM sensors rely on elastic light scattering, providing size-resolved PM concentrations in the 0.3-10.0 ...
... During the calm wind condition, the concentration of the O 3 remains calm for the longer period of time (Ganguly et al. 2006). Similarly, the concentration level of NH 3 , CO and SO 2 (Bgure not provided) increases due to the lower wind speed recorded during winter seasons which allied the local sources from SE and SW directions (Datta et al. 2010;Jayaratne et al. 2021). It is also observed that the lower temperature range during the WSE1 and WSE2 reduces the vertical mixing and lowers the mixing height along with low wind speed, hence resulting in the increase of the concentration of these particulates over the regions. ...
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... Two studies [15,56] deployed their LCS in urban locations near residential non-smoking environments. The most common emissions in urban and suburban sites are industrial, traffic exhaust, and vehicular emissions [1][2][3][4]6,[8][9][10][11][12][13][15][16][17]21,28,[31][32][33][34][35][36][37][38][39][40][41][43][44][45][46][47][49][50][51][52][53][55][56][57][58][59]. Transportation (or traffic) emissions, including gas, vehicle, and diesel combustions, were exposed in forty-three of the studies. ...
... Cao et al. (2021) used LSTM to predict rice yields in China. Ghosh and Behera (2021) used deep learning to estimate the aboveground biomass of mangroves, while Liu et al. (2021) used LSTM technology to expand the use of air quality monitoring data. ...
... By analyzing the light signals detected by the photodiode, the instrument uses static assumptions on the particles' refractive index, shape, and density to estimate the mass concentration of PM in the sample flow [62]. Since these particle properties vary depending on the emissions source, atmospheric humidity level, and other factors, optical PM monitors must be regularly calibrated against gravimetric filter measurements and corrected for erroneous sensitivity to environmental fluctuations and other external factors [63][64][65][66][67]. ...