Why air pollution in India requires compact monitoring stations

Why air pollution in India requires compact monitoring stations

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Last Updated

17 November 2021


09 June 2016




I recently returned from a tour of India which took in the megacities of New Delhi, Mumbai, Hyderabad, Bangalore, plus the smaller cities of Pune and Vishakhapatnam.

What struck me most on this trip was the depth of air pollution knowledge from people in the street. Locals in hotels, bars and airports chatted about PM10 and PM2.5 (particulate matter of less than 10 and 2.5 microns) and other pollutants as if they were everyday topics. I was not expecting this outside of meetings with the Central Pollution Control Board (CPCB) and various State Pollution Control Boards (SPCB).

What has prompted this consciousness and what does it mean for air monitoring in India?

Increasing public awareness of the need for air quality monitoring

The heavily publicized national Air Quality Index or AQI (see our blog on AQI here) announced in 2015 has done much to increase public awareness. Additionally, the Indian Institute of Tropical Meteorology (IITM) in Pune and the media have done a great job in raising mindfulness of air pollution in India.

A new study by the Pune-based IITM and published in Geophysical Research Letters reveals that inhaling PM2.5 and ground-level ozone reduces life expectancy of Indians by an average of 3.4 years with residents of Delhi losing an average of 6.3 years. Future increases in PM2.5 concentrations may actually worsen the situation.

One of the study authors, Sachin Ghude is quoted as saying that, “Upward trends in transportation, industrial and energy sectors, urbanization, population growth in India, along with climate change, will raise the levels of Ozone and PM2.5 in the future, which could worsen the vulnerability of a growing population.”

This increasing public awareness is putting more scrutiny on air quality monitoring, accurate reporting, and air pollution control measures. Although the AQIs have drawn attention to the air pollution problem, experts say they are at best indicative because in most cities there are very few monitoring stations, often located in background areas or less polluted locations, and sometimes these are out of order.

Even in Delhi, where it was hard to miss the green placards that read: “We will make a pollution free Delhi,” I learned that there are only 10 to 12 locations with air quality monitors.

With increasing urbanization and industrial activity promoted by the Make in India initiative, the absence of air quality data restricts government agencies from taking material steps to reduce air pollution. A common plea I fielded from many quarters on this trip was, “We need more air quality monitors in the right places.”

Could a compact air quality monitoring station be the answer for India?

What is a compact air quality monitoring station (CAQMS)?

A compact air quality monitoring station, or CAQMS, like the Aeroqual AQM 65, is a complete air monitoring station in a box the size of a large suitcase. It is equipped to measure the air pollutants designated under the Indian AQI that include particulate matter (PM), ozone (O3), nitrogen dioxide (NO2), carbon monoxide (CO) and sulphur dioxide (SO2), as well as meteorological parameters.

The AQM 65 differs from conventional monitoring stations in India by its much smaller size, reduced complexity and is less expensive to own and operate.

Some of these mini-stations are sufficiently advanced that they can deliver Near Reference data. The term Near-Reference quality data is linked to established air monitoring standards, reference methods, calibration protocols and data quality objectives defined by the US Environmental Protection Agency (EPA) and in the European Union directive 2008/50/EC.

The Aeroqual AQM 65 is one such leading edge Near Reference air quality monitor. The data from this compact station is of sufficient accuracy and quality to supplement routine ambient air monitoring networks and enhance source compliance monitoring. How can this level of performance from a CAQMS be of benefit to India?

Quality and quality of data sources

There is a clear link between the quality and quantity of monitoring data sources and successful air pollution control policies. According to the System of Air Quality and Weather Forecasting And Research, also known as SAFAR, based at IITM-Pune, for an air quality index to be truly representative of a city, single stations and single hourly data are not suitable as they will be biased towards a particular activity or environment.

So air quality needs to be considered from different micro-environments including Background; Commercial; Urban; Suburban; Residential; Industrial; Road side; Traffic junction etc.

The challenge in monitoring air pollution in India has been where to install monitoring stations in areas that are constricted and how to sustain air quality monitoring networks with budget constraints. With limited and very small sites available, CAQMS are a perfect solution as they can be installed on street infrastructure, fence lines and even run on solar power in remote areas.

In addition, at between two and five times lower cost than conventional monitoring stations it is possible for agencies and industry to build and operate sustainable air quality monitoring networks.

Finally, compact stations that deliver Near Reference data can provide stakeholders with assurance that their air quality data is defensible and meets their minimum data quality objectives.

CPCB and DPCC perform trials

In an innovative response to the growing demands for monitoring air pollution in India, the Central Pollution Control Board (CPCB) recently evaluated the Aeroqual AQM 65, a low cost CAQMS capable of providing Near-Reference air quality data. The performance of the station was demonstrated in a four-month trial in central Delhi.

A certified calibration by TÜV India was performed and the CAQMS delivered Near Reference data for particulate matter PM10 and PM2.5, ozone (O3), nitrogen dioxide (NO2), carbon monoxide (CO) and sulphur dioxide (SO2).

The objective of the trial was to assess the accuracy, reliability and fitness for purpose of the CAQMS under challenging environmental conditions and correlate the data with local reference air quality data. The trial results show the Aeroqual AQM 65 recorded over 95 % validity for daily data and demonstrated agreement with data from the nearby reference station under varied ambient conditions including high (> 1000 µg m3) PM2.5 concentrations during the Diwali period in November 2015.

At the conclusion of the trial the CPCB issued a formal acceptance letter which stated that the AQM 65 was found to “work consistently including data generation up to 90 % and to our satisfaction.” This acceptance opens the door to using this CAQMS for new and existing applications where conventional stations were previously considered impractical or too expensive for SPCBs and industry.

For instance, because the AQM 65 was accepted by the CPCB, the Delhi Pollution Control Committee (DPCC) proposed to trial this CAQMS installed on a van. The aim was to perform mobile air monitoring during the odd-even vehicle pilot scheme in January 2016. The challenge for the DPCC was to collect accurate air quality data in real-time resolution, cost-effectively, and from as many sites as possible during the 15-day trial.

The AQM 65 is the first mobile air monitoring station used to measure the impact of the ‘odd-even’ vehicle policy in Delhi and the mobile monitoring solution attracted media attention from newspapers and television.

When the campaign ended the DPCC was highly satisfied with the operation of the AQM 65 stating that “during the 15-day trial 100 % data capture rate was achieved from more than 100 locations which was a very satisfactory performance” (see case study here). In fact, the January trial was so successful the DPCC commissioned the AQM 65 to be used again during the April-May ‘odd-even’ vehicle scheme.

The availability now of advanced CAQMS capable of accurate data at lower costs can also support civil groups in India to confront government and industry in cases of inaction. For instance, Greenpeace India has launched a campaign to push the government towards deploying monitors in all urban areas and release real-time pollution data to the public. Such transparency has increased awareness and further reduced air pollution as initiatives carried out in China have shown.

Whether you live in India or not, if you would like to understand the air quality in your micro-environment and reduce the cost of monitoring, then a compact air quality monitoring station could be a great solution. Check out Aeroqual’s AQM 65 and real-time particulate monitors.