<p>The Scientometry of nanomaterial applications for NO<sub>2</sub> sensor design based on (<b>a</b>) keyword occurrence, (<b>b</b>) country contributions, and (<b>c</b>) author contributions.</p> Full article ">Figure 1 Cont.
<p>The Scientometry of nanomaterial applications for NO<sub>2</sub> sensor design based on (<b>a</b>) keyword occurrence, (<b>b</b>) country contributions, and (<b>c</b>) author contributions.</p> Full article ">Figure 2
<p>The location of different air pollution stations in twelve regions of Mashhad City.</p> Full article ">Figure 3
<p>Climate data of Mashhad City on 11 August 2024 shown by (<b>a</b>) heat map, (<b>b</b>) AQI calendar, (<b>c</b>) weather and pollution distribution, and (<b>d</b>) NO<sub>2</sub> level.</p> Full article ">Figure 4
<p>The schematic plan of the NO<sub>2</sub> sensor based on the adsorption process in the present study.</p> Full article ">Figure 5
<p>The NO<sub>2</sub> air pollution concentration (ppm) in different stations of Mashhad City, 2017 [<a href="#B46-gases-04-00016" class="html-bibr">46</a>].</p> Full article ">Figure 6
<p>The histogram distribution of all NO<sub>2</sub> pollution emissions between all stations of the case study.</p> Full article ">Figure 7
<p>The logic of the created sensor in the present study.</p> Full article ">Figure 8
<p>(<b>a</b>) The geographical location and distribution of (<b>b</b>) NO<sub>2</sub>, (<b>c</b>) CO, and (<b>d</b>) CH<sub>4</sub> on the map of Mashhad City, Iran, based on Sentinel-5P L2 data.</p> Full article ">Figure 9
<p>The average NO<sub>2</sub> concentration in different cities of India [<a href="#B51-gases-04-00016" class="html-bibr">51</a>]. * Delhi has an uninterrupted ambient air quality monitoring data from 2018 onwards.</p> Full article ">Figure 10
<p>(<b>a</b>) AQI of Iran, (<b>b</b>) AQI of India, (<b>c</b>) Tehran’s AQI details, and (<b>d</b>) Delhi’s AQI details.</p> Full article ">Figure 11
<p>The structure of Petri Net modeling as a controlling framework of the created sensor in the present study.</p> Full article ">Figure 12
<p>The managerial insight into air pollution management for case studies of Iran based on (<b>a</b>) Gharibvand et al. (2023) [<a href="#B54-gases-04-00016" class="html-bibr">54</a>], (<b>b</b>) Ghozikali et al. (2014) [<a href="#B55-gases-04-00016" class="html-bibr">55</a>], (<b>c</b>) Azimi et al. (2024) [<a href="#B56-gases-04-00016" class="html-bibr">56</a>], and (<b>d</b>) Karimi et al. (2019) [<a href="#B57-gases-04-00016" class="html-bibr">57</a>].</p> Full article ">Figure 12 Cont.
<p>The managerial insight into air pollution management for case studies of Iran based on (<b>a</b>) Gharibvand et al. (2023) [<a href="#B54-gases-04-00016" class="html-bibr">54</a>], (<b>b</b>) Ghozikali et al. (2014) [<a href="#B55-gases-04-00016" class="html-bibr">55</a>], (<b>c</b>) Azimi et al. (2024) [<a href="#B56-gases-04-00016" class="html-bibr">56</a>], and (<b>d</b>) Karimi et al. (2019) [<a href="#B57-gases-04-00016" class="html-bibr">57</a>].</p> Full article ">