Role of low cost sensors and hybrid networks in India

Air pollution is a growing public concern across the world. Latest Data shows that every year approx 7 Million people die as early as a consequence of air pollution. 99% of the entire human race is breathing unsafe air. In fact, studies show that air pollution may be damaging every organ and virtually every cell in the human body, according to a comprehensive global review.

Why is ambient air quality monitoring important?

With more and more industrialization, air pollution is growing not just in cities but also in rural areas. Vehicular pollution, industrial emissions, road dust, construction dust, waste burning, biomass burning, brick kilns, thermal power plants, and wood-fired cooking are some of the sources driving air pollution across cities and towns, affecting the health of citizens.

Air quality monitoring is the first step to solving air pollution. Oftentimes we hear that ‘we know that air pollution is bad, why do we need monitoring, let's focus on solutions’. However, how do you solve something that you can’t measure?

In order to actually solve the air pollution problem, we need to do the following:

1. Defining the baseline of air quality for a specific region: Air quality is not the same everywhere. It changes based on geography, weather conditions, seasons, and local sources of air pollution. It is essential to define a baseline of air quality from which we can start working on reduction for a particular region.

2. Understanding of the sources and the problem areas: Once we have this data, then analysis can be done to recognize sources of air pollution and their contribution as well as identify the hotspots where action needs to be taken.

3. Evaluation of the solutions: Once we understand the problem, solutions can be devised and deployed. Post-deployment, monitoring will help us measure the effectiveness of the solution. This enables us to focus on more effective solutions and not waste public money on ineffective solutions.

4. Understanding the long-term outcome: Finally tracking air quality data over large periods of time like several years can start showing us how the air quality is improving or degrading over time, so that overall clean air policy can be evaluated for its effectiveness and modified as needed.

Data is also essential to drive awareness amongst the public and enable them to manage their health better.

In a democracy, the Government will only focus on the issues that the public cares about, and the public will care about air quality when they are aware of the problem and can understand the health impact of the air they are breathing.

Access to air quality data will also enable citizens to make better health decisions for themselves and their families to protect themselves from the health hazards of air pollution. For example they may choose to wear a mask when air quality outdoors is poor, or work as a community with local bodies to reduce local sources of pollution, etc.

So how do we monitor Air Quality?

The Government today monitors air quality using regulatory grade air quality monitors. This includes BAMs for particulate matter and various gas analyzers for different gases. For the purpose of this blog, we will focus more on the particulate matter as there are significant health studies that talk about the harmful effects of particulate matter.

BAM or Beta Attenuation Monitor


BAM (Beta attenuation monitoring) is a widely used air monitoring technique used by most regulatory grade monitors.

At a high level, the air is drawn from outside of the detector through a(cycling) ribbon made from some filtering material so that the particles are collected on it. There are two sources of beta radiation placed one before and one after the region where airflow passes through the ribbon leaving particles on it and there are also two detectors on the opposite side of the ribbon, facing the detectors. The sources' intensity and detectors' sensitivity being the same, the intensity of beta rays detected by one of the detectors is compared to that of the other. Thus one can deduce how much mass the ribbon acquired upon being exposed to airflow. Learn more

Low costs sensors (LCS):

Low-cost air quality sensors are a relatively new and affordable technology that measure specific air pollutants, typically particulate matter and occasionally gaseous pollutants, and cost much less than traditional air quality monitors. Rapidly developing technology is being used globally by several government regulators (EPA, UK Govt, etc) for citizen-focused air quality solutions.

Working Principle of a Low-Cost Sensor:

Low-cost sensors are optical sensors based on light scattering. When the light passes through the detecting area, the light from a laser is scattered by the particles in the air. The scattered light is transformed into electrical signals and these signals are amplified and processed. The number and diameter of particles are then obtained by analysis based on existing relationships between signal waveform and particle diameter.


Why are low-cost sensors important?

In India, we have about 7000 rural blocks and 8000 urban areas. Today continuous Govt. AQ monitoring or CAAQMS covers only 330 locations in 171 cities/towns with regulatory grade sensors. There is absolutely no data for any rural blocks, as a result of which NCAP today does not even cover any rural areas. And even among the larger cities and towns, there is no data for most of them, so they do not fall under non-attainment cities.

This is because regulatory-grade equipment is extremely expensive to buy, deploy and maintain. As a country, we do not have the resources to cover the whole country with regulatory-grade equipment.


Regulatory Grade

Low-Cost sensors


Regulatory grade sensors are very expensive. Each regulatory grade site costs Rs. 1.5 Crore each ($200K) and nearly Rs 15 Lakhs per pollutant.

Low-cost sensors on the other hand are 40x cheaper.


Regulatory grade sensors are bulky, require large dedicated space, and take weeks for deployment.

Low-cost sensors can be set up in minutes anywhere – in balconies, poles, etc.


Regulatory grade sensors require significant maintenance, dedicated personnel, and ongoing costs.

Low-cost sensors are easier to maintain and require 1-2 visits per year.

Adoption of low-cost sensors internationally

Low-cost sensors are being adopted more and more across the world for this specific reason and are clearly the future of granular monitoring. Rapidly developing low-cost monitoring technology is being used globally by several government regulators (EPA, UK Govt, etc) for citizen-focused air quality solutions.

  • Paris- Bloomberg Philanthropies launched a pilot program in collaboration with The City Of Paris and Airparif to strengthen air quality control in Paris through the deployment of 150 cutting-edge low-cost sensors of various air pollutants across 44 daycare centers, primary and secondary schools.
  • UK -Environmental Defense Fund Europe (EDF Europe) partnered with the Mayor of London and other experts to launch ‘Breathe London’ to enhance the existing regulatory network and make air quality data accessible across the country by installing a network of 100 low-cost AQMesh sensor pods with each pod containing several air quality sensors.
  • The Great Basin Unified Air Pollution Control District received a grant from the California Air Resources Board to deploy a network of 10 monitoring stations (6 Towns and 4 regions) with low-cost sensors throughout Inyo, Mono, and Alpine Countries to provide particulate matter (PM) data for smoke and dust which will be particularly useful during wildfire season.
  • Taiwan’s Environmental Protection Administration (EPA) advocates the intellectual concept of “Development and application of the environment Internet of things (IoT) sensor network” and hence deployed a network of 10,200 sensors across the country in order to promote environmental governance and the quality of public service.
  • China- 8 Sensor networks were deployed in Xinxiang city of China to improve the spatiotemporal resolution of ground-level PM concentration data.

Airveda Ambient Air Quality Monitors:

Airveda is one of the oldest and leading manufacturers of ambient low-cost sensors in India. In a country where air pollution is one of the biggest health hazards, Airveda was created with a mission to help people breathe well, live well.

We believe that by enabling low cost monitoring in India we can help citizens make informed decisions about the air they breathe, enabling them to lead healthier lives.

Airveda Outdoor Air Quality Monitor

While India is relatively behind when it comes to leveraging low cost monitoring for managing their air pollution problem, we are starting to see various state Government bodies, philanthropies and institutes investing in this. We now have several networks running in multiple cities and continue to work on more:

  • Gurgaon - In partnership with GMDA, Carrier and United Way we have deployed a network of 8 sensors and 3 more coming. We recently won the ICAC challenge as part of this we are deploying 8 more sensors in Gurgaon.
  • Chennai - 40 sensors in Chennai in partnership with IIT Kanpur and Ericsson.
  • Kanyakumari - 5 sensors in partnership with IIT Kanpur and Ericsson
  • Rural areas- Currently working on a project to deploy 1380 sensors in rural areas of two major states, in partnership with IIT Kanpur, Open Philanthropy and Respirer Living Sciences. Read more here. This will be one of the first of its kind, deployments, and will help us understand what over 60% of India’s population is breathing. Currently rural areas are not included in the National Clean Air Plan because of lack of data in these areas.

Hybrid networks

While low cost sensors are affordable and easy to maintain and deploy, one of the biggest reasons why their adoption has been slow is due to the need for calibration against reference grade monitors. Low cost sensors use optical-based sensors that are able to measure the size and number of particles but give ug/m3 value as output which assumes a certain density of particles. As density and composition of particles changes geographically and seasonally they often need regular calibration via colocation with a BAM.

Hence the answer to the air quality monitoring problem is now low cost sensors or regulatory grade sensors but really low cost and regulatlory grade sensors or hybrid networks.

In a hybrid network, a few regulatory grade sensors can be set up in a geographic area with similar seasonal conditions and terrain, and a more dense low-cost sensor network can be built around it which can be regularly calibrated using co-location with the regulatory grade sensors. Our network in Gurgaon in partnership with GMDA, Carrier, and United Way is such a hybrid network.

We believe that low cost sensors and hybrid networks are the future and the only way to be able to monitor air quality across a country our size on a large scale. We continue to work towards innovating in this space and championing low-cost air quality monitoring in the country.

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About the author

Airveda team is a group of individuals working tirelessly with a mission to help people breathe well and live well.