Development of data correction model for low-cost particle sensors under ambient conditions

物联网（IoT）技术的进步使得绘制大空间尺度区域的空气质量变化成为可能。这种技术的部署需要大量的低成本传感器。为了监测PM2.5（空气动力学直径不超过2.5微米的悬浮气溶胶颗粒）在城市市区等大面积的分布，需要数百个低成本的PM2.5传感器。这种传感器大多基于光散射技术，其读数是由制造商用标准气溶胶校准的。校准曲线只适用于特定条件下的某些气溶胶（例如湿度、温度等），这使得它们的读数与环境监测机构使用的基于质量或β衰减技术的结果相比较时存在问题。因此，有必要将低成本的PM2.5传感器与环境主管部门认证的技术在现实条件下进行校准，以便传感器网络能够为空气质量评估提供可接受的监测数据。SensorUp是一家领先的基于物联网技术的传感器网络提供商，已经部署了一个由200多个PM2.5传感器组成的空气质量监测网络，覆盖了卡尔加里大都市75%的面积。该公司有兴趣对气溶胶特性和气象因素对传感器读数的影响进行深入的定量研究，并开发一种校准传感器的方法，以便它们可以提供与卡尔加里地区空气保护区（CRAZ）使用的认证仪器相当的读数。本研究的结果不仅将提高SensorUp在PM2.5监测方面的能力，而且该方法也可转移到其他仪器/污染物，为环境监测机构和服务提供商提供了进行高分辨率监测的低成本选择。

The advancement of the Internet of Things (IoT) technology makes it possible for mapping air qualityvariations in large spatial scale regions. Deployment of such technology requires large number low-costsensors. To monitor PM2.5 (suspended aerosol particles with an aerodynamic diameter no more than 2.5micrometers) distribution in a large area such as the urban area of a city, hundreds of low-cost PM2.5 sensorsare required. Such sensors mostly are based on light scattering technology, and the readings were calibratedwith standard aerosols by their manufacture. The calibration curves are only valid for certain aerosols undercertain conditions (e.g., humidity, temperature, etc.), which makes their readings questionable when comparingwith the results from mass or beta-attenuation -based technologies used by environmental monitoring agencies.Therefore, there is need to calibration the low-cost PM2.5 sensors against the certified technologies byenvironmental authorities under the real-world conditions so that the sensor network could provide acceptablemonitoring data for air quality assessment.SensorUp is a leading sensor network provider based on IoT technology that has deployed an air qualitymonitoring network consisting of 200+ PM2.5 sensors to cover 75% of the area of metropolitan Calgary. Thecompany is interested in an in-depth, quantitative study of the impacts of aerosols properties andmeteorological factors on the readings of their sensors and developing a method to calibrate the sensors so thatthey can provide comparable reading with the certified instrument being used by Calgary Regional AirshedZone (CRAZ). The outcome of this study will not only improve SensorUp's capacity in PM2.5 monitoring, butthe method is also transferable to other instrument/pollutant providing environmental monitoring agencies andservice providers a low-cost option for conducting high-resolution monitoring.