Ahmedabad's New Air Quality Monitors Advance Public Health

Co-authored by Sayantan Sarkar, NRDC India Team

One year ago, citizens of Ahmedabad, India had a limited grasp of the scale of the city’s air pollution levels, even though it is the world’s leading environmental health risk. Without credible data, the city government, which has been making great strides in protecting its seven million citizens from deadly heat waves, was unable to warn them about unhealthy levels of air pollution.

The Ahmedabad Municipal Corporation (AMC) city administration, working along with knowledge partners at the Indian Institute of Public Health-Gandhinagar (IIPH-G), Indian Institute of Tropical Meteorology (IITM), and NRDC launched the Air Information and Response (AIR) Plan in May 2017 – a first of its kind city-led air pollution early warning system and health risk communication plan in India. Ahmedabad has undertaken proactive steps with this plan to better quantify its air pollution problem. Specifically, with the leadership and expertise of the IITM’s System of Air Quality and Weather Forecasting and Research (IITM-SAFAR) team, the city has deployed a suite of new air quality monitors, established a health-focused Air Quality Index (AQI), and developed an emissions inventory that guides current and future exposure reduction efforts. A year into the plan, we are taking a closer look at how these tools document local conditions, communicate to city residents about risks to their health, and inform policy solutions to achieve cleaner air.

New Monitoring of Local Air Quality

IITM-SAFAR, with support of Government authorities and civil society, deployed a suite of 10 joint air pollution and weather monitors in and around Ahmedabad, each collecting data at 5-minute intervals. These monitors are sited and operated according to standards set by the Government of India’s Central Pollution Control Board and the World Meteorological Organization.  IITM-SAFAR has also adopted the U.S. Environmental Protection Agency (U.S. EPA) Standard Operating Procedures for instrument calibration and maintenance. These state-of-the-art continuous air quality monitors, with highly accurate sensors certified by U.S. EPA, are distributed throughout the city, and document spatial variation in levels of key pollutants like fine particles (PM_2.5), ozone, (O₃), nitrogen oxides (NO_X), and sulfur dioxide (SO₂) over time. The data collected by these monitors feeds directly into the AQI, which distills raw air pollution data into a single, accessible summary metric. Ahmedabad’s AQI system is based on the best practices of other systems operated by SAFAR in India (Delhi, Mumbai, and Pune) and lessons learned from air quality managers in other cities grappling with air pollution (including Los Angeles, Mexico City, and Beijing, amongst others).

Ahmedabad’s AIR Plan was designed with the data-driven AQI as its centerpiece. The plan helps the city government coordinate internally and communicate externally about air pollution conditions and measures that citizens (especially vulnerable groups like children and those with pre-existing medical conditions) can take to reduce harmful exposures.  The daily AQI, categorizing air quality in five categories ranging from good to severe, is available online, through email alerts and mobile phone applications, a toll-free automated phone system, and on ten prominent electronic display boards placed around the city.  The air quality data collected in Ahmedabad also helps researchers to analyze pollution trends over time, understand local hot spots of high pollution levels, and investigate the short- and long-term health risks associated with exposures in partnership with public health experts at IIPH-G.

Emissions Inventories Identify Key Sources of Air Pollution

Many sectors (e.g., transportation, power generation, agriculture, solid waste burning) contribute to the air pollution problem in India and quantifying the relative contributions of each sector is key for shaping efforts to reduce polluting emissions at the local level.  How do scientists identify and rank these specific sources of air pollution?  An emissions inventory is a comprehensive list, by source, of the amount of air pollution emitted in a particular area over a specified time period. These lists are representative of long-term average conditions and as such, the development of local, source-specific emissions information is ideal.

In 2017, IITM-SAFAR research established the first comprehensive emissions inventory for Ahmedabad. The inventory covers the metropolitan region for key health-damaging pollutants like small particles (PM_2.5 and PM₁₀), but also other pollutants that threaten health like ozone precursors of nitrogen oxides (NO_X) and volatile organic compounds (VOCs), carbon monoxide (CO), and sulfur dixiode (SO₂). IITM’s emissions inventory relied on a major data collection effort to quantify air pollution sources directly through on-the-ground field surveys and indirectly from reviews of government and industry records. More than 200 student volunteers collected over 81,000 survey data points that contributed to the Emissions Inventory. These researchers also retrieved data from local authorities like the AMC city government, neighboring Gandhinagar city government, state-level Gujarat Pollution Control Board , and individual industrial site operators such as local power plants.

The key results from Ahmedabad’s first emissions inventory for small particles (PM_2.5) indicate that two sectors, transportation and industry, are responsible for more than two-thirds of polluting emissions. The other contributors were wind-blown dust (21%), residential emissions from activities like solid fuel combustion (7%), and open trash burning (3%).  Overall, the results revealed that the transport sector is the largest contributor to PM_2.5, ozone precursors (NOx and VOCs), and carbon monoxide. whereas industrial emissions contribute the most to coarse particle (PM₁₀) levels and health-damaging SO₂ pollution.  The emissions inventory includes a sectoral breakdown for each pollutant of concern, to allow for a detailed understanding of local conditions.

Using Data to Shape Policy and Protect Health

In the near term, the new emission inventory and air quality monitoring data are important for understanding atmospheric chemistry and improving the precision of models that forecast air quality. A key component of SAFAR’s AQI system is the daily air quality forecast that alerts citizens to high pollution episodes far enough in advance so that they can prepare and plan their daily activities in ways that reduce their exposure to polluted air. These forecasts also inform Ahmedabad’s School Flag program, which helps to protect children from unhealthy air by raising awareness to each day’s AQI forecast and associated actions students can take to protect their health.

The emissions inventory indicates that longer-term policy solutions in the transportation sector such as encouraging modal shifts to boost public transport use, enforcing strong vehicle fuel standards, and promoting electric vehicle adoption will help achieve major air quality and health benefits in Ahmedabad. To address industrial emissions, the city could consult with plant operators within the city perimeter as well as thermal power generators to ensure that facilities are compliant with emission and control technology norms. Each potential solution is sector-specific: windblown dust can be reduced by spraying roadways with water in dry weather, while cleaner fuels can be deployed to households to meet heating and cooking demands rather than polluting solid fuels and trash. About 25% of India’s outdoor air pollution problem stems from indoor air pollution, and policies that consider these exposures jointly are crucial. The Emissions Inventory also equips citizens with an evidence base to demand actions to reduce vehicle pollution and continue to monitor pollution from industrial sources. Importantly, Ahmedabad’s expert working group on air pollution is utilizing the emissions inventory findings to inform its investigation of policy options to reduce air pollution in the city.

A Path Forward

Ahmedabad’s newly-available quality monitoring data, AQI system, and emissions inventory are helping to drive local evidence-based action to address the city’s air pollution challenge. These three tools, developed and deployed in-country by the Indian Institute of Tropical Meteorology in collaboration with city leaders, are instrumental in guiding the city’s path to cleaner air for its residents.