Assessment of the exposure to PM2.5 in different Lebanese microenvironments at different temporal scales

Abstract

The weak potential of using the sole outdoor concentrations to represent personal exposure to PM_2.5 is confirmed by the literature; therefore, it is important to account for a person's movements over time when estimating the short-term personal air pollution exposure within different microenvironments (MEs). This study is an example of applying an assessment method of the exposure to PM_2.5 in different microenvironments at different temporal scales. A low-cost particle counter (the Dylos 1700) was used; its performance was validated in comparison with equivalent instruments such the SidePak AM520 Personal Aerosol Monitor (R² = 0.89). This validation also provided a function to convert measured particle number concentrations (PNCs) into calculated particle mass concentrations. The 150 profiles that was collected on a minute-by-minute basis regarding PM_2.5 concentration from December 2018 to May 2021 highlight the influence of individual activities and contextual factors on the air quality, so that Lebanon's annual PM_2.5 mean (24.2 µg⁄m³) is 142% higher than the World Health Organization (WHO) annual mean guideline (10 µg⁄m³). Winter is the most polluted period due to the increased application of space heating devices. Additionally, the occurrence of dusty winds during the spring period leads to the elevated levels of dispersed PM_2.5. Simultaneously, the rural zones are more polluted than urban ones due to the usage of more traditional heating equipment, in addition to the usage of chemical products like pesticides and fertilizers in agricultural activities in such areas. Furthermore, the (outdoor-indoor-transport) MEs indicate that the transport and indoor MEs have similar levels of suspended fine particulates, while outdoor MEs are less polluted. Studies based on the personal exposure to PM_2.5 were generally applied on specific and limited places such as schools, workplaces, or residences. The study aims to shed light on the modern method in an attempt to estimate the personal exposure to PM_2.5 and to inspire similar studies to achieve the maximum efficiency.

Keywords: Air pollution; Fine particulate matter; Microenvironments; Personal exposure; Portable monitoring tool.

Fig. 1

Lebanon’s location in the world map (a), monitoring sites of PM_2.5 on Lebanon’s scale (b), North Lebanon’s scale (c), Beirut’s scale (d), and South Lebanon’s scale (e)

Fig. 2

The monitoring pack of our study (left), the Dylos DC 1700 monitor of PMs (right)

Fig. 3

A plot that shows the relationship between the recorded data by Dylos (PNC) and the SidePak ([PM]); Dylos PNC (# for particles between 0.5 and 2.5 µm in ft.⁻³)

Fig. 4

Two illustrations of an urban profile like Beirut (a) and a rural profile like Kfarhouna (b)

Fig. 5

Average temperature fluctuation starting from 30 December 2018 to 17 June 2021 (left); determination of the period of each season (right)

Fig. 6

[PM_2.5] in rural and urban areas during the whole period of study, starting from 9 December 2018 to 16 May 2021

Fig. 7

[PM_2.5] in the three main MEs, starting from 9 December 2018 to 16 May 2021

Fig. 8

[PM_2.5] in rural and urban areas during the four typical seasons, starting from 9 December 2018 to 16 May 2021

Fig. 9

[PM_2.5] in rural and urban areas following (IOT) classification during the four typical seasons, starting from 9 December 2018 to 16 May 2021

Fig. 10

Mobile profile between home (urban) and office (urban) between 9 December 2018 and 10 December 2018 (P1-01); MME, mean of the [PM_2.5] in each ME

Fig. 11

Mobile profile between the first home (Rwes) and the second home (Kfarhouna) between 15 December 2018 and 16 December 2018 (P1-02); Note: “sobia” is a wood’s based heater

Fig. 12

Mobile profile between Beirut and Labweh between 22 December 2018 and 23 December 2018 (P1-03)

Fig. 13

Mobile profile between Beirut, Amioun, and Tripoli between 3 March 2019 and 28 March 2019 (P2-01)