Toxic foam returns to Yamuna as AQI touches 168, GRAP-1 restrictions in force

The foam is a thick layer floating on the Yamuna’s surface near Kalindi Kunj. It is not a separate solid structure or a natural feature of the river. Its return is a highly visible warning that pollution remains a serious problem in Delhi’s waterway.

Foam commonly forms when polluted water contains substances such as detergents, organic waste, or other chemicals that trap air. Movement in the river can gather these substances into bubbles and surface layers. The article does not identify the foam’s exact chemical composition, but it presents the sight as evidence of continuing river pollution.

The latest foam appeared days after Chief Minister Rekha Gupta highlighted projects intended to revive the Yamuna. The government has inaugurated infrastructure projects worth approximately ₹9,000 crore and says it is working toward a clean, uninterrupted-flowing river. The foam shows that large investments have not yet ended the visible pollution problem.

An Air Quality Index of 168 indicates unhealthy air quality. This means polluted air can affect people’s health, especially those with breathing or heart problems, children, older adults, and people who spend a lot of time outdoors. Even healthy residents may choose to reduce prolonged outdoor exposure when pollution is high.

The article identifies PM2.5 and PM10 as Delhi’s main pollutants. These are tiny airborne particles. PM2.5 is especially small, while PM10 includes somewhat larger particles that can still enter the respiratory system. Delhi’s monitoring stations measure these particles because they were dominating pollution levels when the overall AQI reached 168.

Conditions were not identical across the city. The reading was around 110 at PGDAV College in Sriniwaspuri, while several stations reported between 118 and above 180. The worsening air prompted CAQM to invoke Stage 1 of GRAP across Delhi-NCR on October 21.

PM2.5 and PM10 are categories of particulate matter, meaning tiny solid or liquid particles suspended in the air. PM2.5 particles are finer than PM10 particles. Their size matters because smaller particles can travel deeper into the respiratory system. Both are important indicators of air pollution and potential health risk.

Delhi’s monitoring stations track these particles as part of air-quality measurement. The article reports that PM2.5 and PM10 continued to be the primary pollutants across the national capital. Their measured concentrations helped determine the AQI, although readings differed from one monitoring station to another.

For example, PGDAV College in Sriniwaspuri recorded an AQI of around 110. Other stations reported readings from 118 to above 180. Together, these readings show why particle pollution was central to Delhi’s worsening air-quality picture and why CAQM activated Stage 1 of GRAP across Delhi-NCR.

Stage 1 of the Graded Response Action Plan is an emergency pollution-control step. It changes what certain businesses may burn and when generators may operate. The aim is to reduce additional emissions while air quality worsens across Delhi-NCR.

Under the restrictions, hotels, restaurants, and open-air eateries cannot use coal or firewood in tandoors. Diesel generators are restricted to essential and emergency purposes. These rules remove some routine combustion sources from daily activity, although the article does not list every measure included in Stage 1.

The Commission for Air Quality Management invoked Stage 1 across Delhi-NCR on October 21. The decision followed worsening air quality, with the overall AQI reaching 168 and PM2.5 and PM10 dominating pollution levels. As a result, affected businesses must change cooking or backup-power practices while the restrictions remain in force.

Foam forms when wastewater carries substances that lower water’s surface tension. Detergents are especially effective because they contain surfactants, chemicals that help water spread and lift grime. Sewage can add organic matter, while industrial discharges may contribute chemicals that alter the water’s properties. Together, these materials make stable bubbles easier to form.

As water moves, falls, or mixes, air becomes trapped in it. Turbulence then brings the bubbles to the surface. Surfactants help keep them from bursting quickly, so the bubbles collect into white foam. Organic material can make the foam thicker and longer-lasting. The article shows the result at Kalindi Kunj but does not identify the exact substances present there.

This mechanism explains why visible foam can return even after major projects are announced. If polluted wastewater continues entering a river, new foam can form when conditions are suitable. The article therefore presents the resurfacing as evidence that Yamuna pollution remains unresolved despite ongoing rejuvenation efforts.

The reported investment is large, but the article gives two related figures. Chief Minister Rekha Gupta said projects worth approximately ₹9,000 crore had been inaugurated. She also described the latest investment as following projects worth ₹9,000 crore to ₹10,000 crore initiated last year.

The spending supports major infrastructure work in Delhi, with a primary focus on rejuvenating the Yamuna. The article does not provide a project-by-project breakdown or name specific treatment plants, drains, or river structures. It does state that the initiatives form part of ongoing efforts to clean and revive the river.

Gupta said the government wants the Yamuna to become clean and flow uninterrupted within a few years. However, thick foam resurfaced near Kalindi Kunj soon after her statements. That contrast shows the scale of the challenge: major investment is underway, but visible pollution continues and the cleanup’s results are not yet complete.

Cleanup projects can remove pollution already present in a river, but they cannot provide lasting results if new wastewater continues to arrive. Wastewater treatment reduces harmful material before discharge. Pollution controls limit what homes, businesses, and industries release. Together, they protect the river after construction or restoration work is completed.

The basic mechanism is continuous prevention. Untreated sewage, detergents, and industrial pollutants can change water quality and create conditions for surface foam. If those inputs are not controlled, a river may look cleaner briefly but become polluted again. Treatment and enforcement therefore need to operate alongside infrastructure projects.

The Yamuna’s renewed foam near Kalindi Kunj illustrates this challenge. The government has announced major infrastructure investments and promised a clean, uninterrupted-flowing river. Yet visible foam has returned. That suggests rejuvenation must address ongoing pollution sources as well as building large projects, or the river’s improvements may not last.