Trace gases and PM2.5-bound metal abundance over a tropical urban environment, South India

AbstractThe largest group of Indians in West Malaysia are the Tamil-speaking Hindus who originate from South India, particularly from Tamilnad. According to S. Arasaratnam, not only are 80% of Indians in Malaysia Tamil speakers but a vast majority of them are also Hindus.1 It is further established that the majority of this group are members of the working class, either in the plantation or in the urban sectors. The family structures of these Tamil working-class families originate basically from the traditional Indian family structure of India. This traditional Indian family structure was maintained in the "conducive" environment of ethnic isolation, found in the plantations. Since my purpose is to study changes in the family structure, Tamil working-class families in an urban environment were selected. It is expected that some changes in family values and structures have occurred among this group of Indians in West Malaysia.

Download Full-text

Added Value of Vaisala AQT530 Sensors as a Part of a Sensor Network for Comprehensive Air Quality Monitoring

Frontiers in Environmental Science ◽

10.3389/fenvs.2021.719567 ◽

2021 ◽

Vol 9 ◽

Author(s):

Tuukka Petäjä ◽

Aino Ovaska ◽

Pak Lun Fung ◽

Pyry Poutanen ◽

Jaakko Yli-Ojanperä ◽

...

Keyword(s):

Air Quality ◽

Urban Environment ◽

Sensor Network ◽

Temporal Variability ◽

Trace Gases ◽

Fine Tuning ◽

Added Value ◽

Wood Combustion ◽

Spatio Temporal ◽

The City

Poor air quality influences the quality of life in the urban environment. The regulatory observation stations provide the backbone for the city administration to monitor urban air quality. Recently a suite of cost-effective air quality sensors has emerged to provide novel insights into the spatio-temporal variability of aerosol particles and trace gases. Particularly in low concentrations these sensors might suffer from issues related e.g., to high detection limits, concentration drifts and interdependency between the observed trace gases and environmental parameters. In this study we characterize the optical particle detector used in AQT530 (Vaisala Ltd.) air quality sensor in the laboratory. We perform a measurement campaign with a network of AQT530 sensors in Helsinki, Finland in 2020–2021 and present a long-term performance evaluation of five sensors for particulate (PM10, PM2.5) and gaseous (NO2, NO, CO, O3) components during a half-year co-location study with reference instruments at an urban traffic site. Furthermore, short-term (3–5 weeks) co-location tests were performed for 25 sensors to provide sensor-specific correction equations for the fine-tuning of selected pollutants in the sensor network. We showcase the added value of the verified network of 25 sensor units to address the spatial variability of trace gases and aerosol mass concentrations in an urban environment. The analysis assesses road and harbor traffic monitoring, local construction dust monitoring, aerosol concentrations from fireworks, impact of sub-urban small scale wood combustion and detection of long-range transport episodes on a city scale. Our analysis illustrates that the calibrated network of Vaisala AQT530 air quality sensors provide new insights into the spatio-temporal variability of air pollution within the city. This information is beneficial to, for example, optimization of road dust and construction dust emission control as well as provides data to tackle air quality problems arising from traffic exhaust and localized wood combustion emissions in the residential areas.

Download Full-text