These cheap sensors will become a game changer in air quality monitoring

Pilot studies show that low cost sensors fitted with regulatory grade monitors worked more efficiently than expected

Amidst the increasing impact of pollution in the country, there is a great need to expand the necessary network to monitor its levels across India. For this there is a big hurdle in the form of huge investment. In such a situation, low cost indigenous sensing devices (sensors) raise a new hope.

The results of a seven-month pilot study conducted by the Maharashtra Pollution Control Board (MPCB) in collaboration with the Indian Institute of Technology, Kanpur (IIT-K) and Bloomberg Philantrophies suggest that low-cost sensors developed by local startups The devices (sensors) worked 85-90 percent efficiency compared to regulatory grade monitoring equipment. These findings are very encouraging as well as lay new ground for envisaging a wider network of Pollution Monitoring Centers in future.
Four different startups developed 40 affordable sensors for this study. The results of the study showed that the sensors developed by the three startups had deviations (error thar) from uncalibrated values ​​(in terms of actual parameters as measured by Continuous Ambient Air Quality Monitoring Stations ‘CAAQMS’) by 25 per cent. After calibration, this error reduced to less than 15 percent in three types of sensors, while this error was 20 percent in the fourth type of sensor.
The study was conducted between November 2020 and May 2021. For this, 40 low cost monitoring sensors were installed along with 15 CAQMS of MPCB currently installed. Of these, 10 sensors were installed in Mumbai and one each in Navi Mumbai, Thane, Kalyan, Vasai-Virar, Zion, Borivali, Airport, Powai and Dombivli.
The sensors, developed by startups Respiror Living Sciences, Airveda Technologies, Personal Air Quality Systems (PQS) and Oizom Instruments, were fitted with MPCB’s regulatory grade air quality BAM (SONA Attenuation Monitoring). These low-cost indigenous air quality monitoring sensors can generate one minute data on PM2.5 (particulate matter with a size of less than 2.5 microns) and PM10 (particulate matter with a size of less than 10 microns). These solar powered sensors are equipped with the feature of real time communication for data transmission.
The findings of this study were presented in a webinar held on Friday. Representatives of the Ministry of Environment, Forest and Climate Change, Ministry of Urban Development, Central and State Pollution Control Boards, technical experts, media and members of civil society also participated in this webinar. The purpose of organizing this webinar is to deliberate on the measures to be implemented under the National Clean Air Program (NCAP) plan for expansion of Air Quality Monitoring Centers in the country.
Dr. SN, Head of the Department of Civil Engineering at IIT-K and National Coordinator of the National Knowledge Network of the National Clean Air Programme. Tripathi said, “The future of air quality monitoring lies in a hybrid approach combining regulatory grade monitors and sensors to provide highly localized data at high temporal frequency. It is clear from the results of the Mumbai sensor experiment that indigenous sensor technology is ready to be deployed on a large scale for air quality monitoring in the country.
Referring to the technical assessment of the low-cost sensor-based pollution monitoring network in Maharashtra, he said that a large amount of data was collected during this period. During this, the sensor worked well even in difficult times like lockdown without any special human support. During this time the error percentage in the sensor data of the two startups fell below 15 and the sensors showed a strong correlation with the CAQMS after calibration.
Sudhir Srivastava, President, Maharashtra Pollution Control Board said that we have many challenges related to the environment, in which air pollution is the most prominent. Each of us breathes 11000 liters of oxygen every day. We can buy water bottles but we cannot imagine buying an oxygen bottle.
He said that when it comes to air pollution, the biggest problem is how to measure the problem. CPCB has started National Air Monitoring Programme. We have about 100 stations established in Maharashtra. If we talk about monitoring air quality in a more meaningful way from a local perspective, then we have to increase the network of air quality monitoring on a very large scale. Very dense monitoring network will be needed. To solve the financial constraints in this, we will need low cost sensors. For this, we have to install sensors that give cheap and almost accurate results. I am glad that even small startups have started working towards solving the problem of air pollution by providing low cost sensors. Entrepreneurs trying to capture data through cost-effective sensors can have great data. I am glad that this report has brought out these findings and has given new hope for the intensification of Air Quality Monitoring Centres.
Dr VM Motghare, Joint Director, Maharashtra Pollution Control Board said that Maharashtra has the maximum number of 18 non-maintenance cities. These cost-effective sensors made by startups for monitoring required under the National Clean Air Program will prove to be very helpful in hotspot technology. One drawback is that these sensors cannot function as a single unit without a traditional monitoring center. Clearly need to be considered.
This pilot study conducted in Maharashtra also reflects the increased uptime that the monitoring system can get through the sensors. The low-cost sensors developed by all the four startups had an uptime of over 95%.
Month-to-month differences have been found in averages calculated by a sensor-based network installed to measure PM 2.5 concentration at each location in the Mumbai metropolitan area. For example, in Vile Parle it was 80 ug/m3 in November which decreased to 26 ug/m3 in May. Some coastal places like Colaba also recorded high pollution levels in the winter months of December with PM2.5 concentration of 56 ug/m3. Kalyan had the highest monthly average of 124 ug/m3 in the month of January.

The results of this study have opened the doors of possibilities for further expansion of the air quality monitoring network in the country at a low cost. While the cost of regulatory category monitors is Rs 20 lakhs, the cost of small sensors made by startups is around Rs 60 thousand. According to an estimate, 4,000 continuous monitoring stations are needed to monitor PM2.5 pollution spatially, temporally and statistically in urban and rural areas of India. Presently there are 286 Continuous Regulatory Grade Monitors and 818 Manual Monitoring Stations located in the country.
Priya Shankar, Director (India) of Bloomberg Philanthropies’ Climate and Environment Program, said, “Air pollution is affecting public health, economic productivity and the environment. Measuring and understanding the levels of air pollution is essential to improve and better manage air quality. The effectiveness of the new and unique sensor technology used in this first of its kind pilot experiment in India is encouraging. These have enormous potential, and when combined with traditional methods, they provide much better data to help us tackle air pollution.”
He said that according to the statistics of the World Health Organization, 90% of the world’s people are forced to breathe poisonous air. The emphasis is on increasing the number of monitors under the NCAP program in India. These cost-effective sensors are still in their early stages, but they can provide better data about pollution levels at a lower cost. Smaller sensors have full potential to complement regulated centres.
The webinar was moderated by Aarti Khosla, Director, Climate Trends. The webinar included Eliot Treharne, Joint Assistant Director, Energy and Environment, Greater London Authority, Kunal Kumar, Director of the Smart Cities Mission, Ministry of Housing and Urban Development, Ronak Sutaria of Respirer Living Science, Namita Gupta of Airveda Technology, A. Vaidyanathan and Ayyan Karmakar of Oizom Instruments also participated.

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