Diwali celebrations leave trail of toxic smoke:How air-quality monitoring stations and satellites track pollution during the festival of crackers

Diwali celebrations light up homes and streets, but the festival leaves behind a thick layer of smoke. Firecrackers release tiny particles into the air, causing pollution levels to rise within a short time. But how do we know when air quality is getting worse, which areas are most affected, and how long the pollution stays? Air-quality monitoring stations, portable pollution sensors, and satellites help scientists and authorities track these changes. Together, they provide information about pollution levels on the ground as well as the spread of smoke across larger regions. Here is how these technologies work and how they help monitor air pollution during Diwali.
Air-quality monitoring stations measure pollution levels Air-quality monitoring stations are fixed installations set up in different parts of cities. In India, the Central Pollution Control Board (CPCB) and state pollution control boards operate monitoring networks to measure pollutants in the air. These stations use specialised instruments to collect air samples and measure the concentration of particulate matter, including PM2.5 and PM10. What are PM2.5 and PM10? Monitoring stations use instruments such as Beta Attenuation Monitors (BAM) and Tapered Element Oscillating Microbalances (TEOM) to estimate the amount of particulate matter in the air. How do they help during Diwali? These stations record changes in pollution levels throughout the day. When firecrackers are burst, they can capture sudden increases in PM2.5 and PM10 concentrations. The readings help authorities compare air quality before, during, and after Diwali. The data is also made available through platforms such as the CPCB’s SAMEER app, which allows people to check air quality information for different locations. Also read: Astronaut Shubhanshu Shukla shares stunning view of Earth from space: Shares video of ‘nature’s fireworks’ ahead of the festival of lights, Diwali

Low-cost sensors track pollution at street level Fixed monitoring stations provide important data, but they cannot capture pollution levels in every street or neighbourhood. This is where low-cost and mobile pollution sensors become useful. Many of these devices use a technology called laser light scattering. As air passes through the sensor, a laser beam falls on the particles present in it. The particles scatter the light, and a detector measures this scattering to estimate their number and size. The device then uses this information to estimate PM2.5 and PM10 levels. How do they help during Diwali? For example, research teams can use mobile monitoring systems to study how air quality changes across different neighbourhoods during Diwali night. However, low-cost sensors are generally less accurate than regulatory-grade monitoring equipment. Their readings can also be affected by humidity and other environmental conditions, so they are most useful when calibrated and compared with reference stations. Satellites provide a bird’s-eye view of pollution While ground stations and portable sensors measure pollution close to the surface, satellites help scientists observe smoke and airborne particles across much larger areas. Earth-observation satellites carry instruments such as MODIS, VIIRS, and TROPOMI, which collect information about the atmosphere and Earth’s surface. One important measurement used in satellite-based air-quality studies is Aerosol Optical Depth (AOD). It indicates how much sunlight is blocked or scattered by tiny particles and droplets present throughout a column of air. A higher AOD reading can indicate a greater amount of aerosols in the atmosphere. However, AOD is not the same as ground-level PM2.5 or PM10. Scientists combine satellite observations with ground measurements and weather information to understand surface-level pollution. How do these three technologies work together? Each technology provides a different part of the picture. Ground monitoring stations offer detailed pollution readings at specific locations, low-cost sensors help track neighbourhood-level changes, and satellites provide a wider view of pollution spread. When combined with weather information, these sources help researchers understand not just how much pollution is present, but also where it is coming from and how it is moving. For instance, ground stations may record a sudden rise in PM2.5 after firecrackers are burst. Nearby mobile sensors can help identify affected neighbourhoods, while satellite observations can show the wider spread of smoke. Also read: Diwali celebrations are becoming more technology-driven: From diyas to smart lights, how digital space is changing India’s biggest festival

Why is real-time pollution tracking important during Diwali? Monitoring air pollution is important because high concentrations of fine particles can affect people’s health, particularly children, older adults, and those with respiratory or heart-related conditions. Timely information can help authorities identify pollution hotspots, issue public health advisories, and plan measures to control emissions. It also allows residents to check local air quality and take precautions when pollution levels are high. However, no single technology can provide a complete picture. Ground stations, low-cost sensors, and satellite data work best when their readings are analysed together. As Diwali celebrations continue to evolve, these technologies are helping scientists understand their environmental impact more clearly and track how pollution changes during and after the festival.