GRAP-3 Restrictions Back In Delhi-NCR, Hybrid Mode Up To Class 5
Last month air quality in Delhi and surrounding areas was consistently in the ‘severe’ and ‘very poor’ category, prompting annual health warnings from doctors.
Delhi’s AQI reached 398 on Monday night, with hotspots like Anand Vihar recording an AQI of 460
The CAQM, or the government’s air quality panel for the national capital region (NCR) of Delhi, has invoked Monday restrictions under stage three of the Graded Response Action Plan, or GRAP, because air quality worsened rapidly and is set to be in a ‘severe’ category with less-than-desirable meteorological conditions.
The 24-hour average air quality index (AQI), captured at 4 p.m. every day, was at 379 on Monday and jumped to 398 by 9 p.m. The Supreme Court on Dec 5 allowed relaxations of the restrictions GRAP IV, implemented from Nov 18, only after it saw that the air quality improved.
As many as 23 out of 37 spots from which data was available had more than 400 AQI at 9 p.m. The highest pollution was seen in Anand Vihar at 460, 446 in Rohini, 444 at Wazirpur, 442 at Jahangirpuri and Vivek Vihar, and 441 at Punjabi Bagh.
The GRAP for Delhi-NCR has categorized the stages of air quality into four. It has Stage 1 for “poor” AQI between 201 to 300; Stage 2 for “very poor” AQI, between 301 to 400; Stage 3 for “severe” AQI, of 401 to 450; and Stage 4 for “severe plus” AQI above 450.
The CAQM observed that at the review meeting that the AQI in Delhi went past the 350 mark on Monday afternoon and deteriorated between 1 pm and 4 pm. It also mentioned that the AQI could worsen because of extremely calm wind and the “build-up of an inversion layer adversely affecting the vertical mixing height,” the height above the surface throughout which a pollutant can be dispersed.
The India Meteorological Department and the Indian Institute of Tropical Meteorology predict that due to persistent unfavorable meteorological conditions, air quality may continue to hover in the range of the higher end of the ‘Very Poor’ to ‘Severe’ category during the coming days.
Keeping in view the prevailing trend of air quality, and in an effort to prevent further deterioration of air quality in the region, the Sub-Committee today has taken the call to invoke all actions as envisaged under Stage-III of revised GRAP – ‘Severe’ Air Quality (DELHI AQI ranging between 401-450), with immediate effect, in the entire NCR.”. In addition to the measures under in Stages I & II of GRAP already in force in NCR, the government said.
Under the revised plan, schools and colleges in Delhi, Gurugram, Faridabad, Ghaziabad and Gautam Budh Nagar would shift classes up to Class V to hybrid mode under GRAP Stage III. Students and parents will have the choice of online education wherever that is available.
In addition, stage III prohibits all non-essential diesel-run medium goods vehicles of BS-IV or older norms within Delhi and non-essential diesel light commercial vehicles of BS-IV or older norms registered outside Delhi.
Delhi and NCR state governments have been further ordered to stagger the opening hours of public offices and municipal bodies under stage III. The Centre will be entitled to decide staggered opening hours for its offices in Delhi-NCR also.
#Pollution reasons in Delhi
Delhi’s air pollution is mainly due to several interlinked reasons:
-Vehicular Emissions: Accounting for 51.5% of pollution, the emissions from more than 9 million vehicles have become a primary source of harmful pollutants .
Stubble Burning: Agricultural practices in neighboring states, particularly during harvest season, form a significant reason for deterioration in air quality.
Construction Dust: Construction activities which are still ongoing release immense dust particles in the atmosphere and increase pollution levels68.
Industrial Pollution: Industries including manufacturing industries and power plants, in terms of particulate matter emission along with other harmful gases.
Burning of waste: Incinerating waste through open burning enhances the mix of toxic pollutants.
These are further aggravated with meteorological conditions particularly a stagnant winter air which makes pollution get trapped close to ground level and aggravate the smog.
#Role played by neighboring districts
Delhi’s pollution is much influenced by neighboring districts by several key mechanisms:
Stubble Burning: Farming activities in the states of Punjab and Haryana are significant sources of air quality degradation; however, this primarily occurs when stubbles from harvesting are burnt and particulate matter into the atmosphere.
Transboundary Pollution: The wind flows bring pollutants from industrial sources and vehicular emissions of other areas into Delhi, adding complexity to local air quality issues.
Regional Cooperation: Effective management of air pollution is possible only through coordinated efforts of urban and rural areas. Some of the strategies used include airshed management and joint action plans for controlling the sources of pollution that cross city boundaries
Overall, the effort to reduce Delhi’s air pollution needs to be collaborative between districts.
#How does weather condition influence the pollution level in Delhi?
Weather conditions are also a very influential factor that determines the pollution level in Delhi:
Temperature Inversion: In winter, cooler surface temperatures can trap pollutants near the ground, creating a “lid” effect that exacerbates smog formation.
Wind Speed: Low wind speeds hinder the dispersion of pollutants, allowing them to accumulate. Conversely, strong winds can help clear the air by dispersing contaminants.
Fog and Humidity: High density fog can cause low visibility and trap pollution, resulting in a sudden hike in AQI levels. The interaction of warm humid air with cold air masses causes this phenomenon.
In general, unfavorable weather conditions severely exacerbate Delhi’s air quality, mainly during the winter season.
#What is the role of humidity in Delhi’s pollution levels?
Humidity greatly influences the pollution level in Delhi through the dispersion and formation of pollutants:
Low Dispersion: Excessive moisture in the air can slow down the dispersal mechanism of pollutants, thus making them stay within the atmosphere. This contributes to higher concentration levels of harmful gases and particles.
Formation of Secondary Particles: Humidity aids the chemical processes that produce secondary particulate matter, which can be much more dangerous than primary emissions. Such processes are frequently found to happen as moist air interacts with pre-existing pollutants.
Effect on AQI: High levels of humidity often accompany bad air quality as witnessed when Delhi records high humidity along with other pollution-emitting activities, leading to “very poor” AQI values.
Over a month in this dryness, humidity is critical for exaggerating air pollution in Delhi mainly during winter months.
During specific seasons of the year
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#Do months pose different humidity levels to worsen air quality in Delhi?
Humidity makes a significant difference in how badly Delhi’s air has been polluted, especially between winters.
Peak Pollution Period : The first half of November has been the most historically polluted time with high levels of humidity, temperature inversion, and stubble burning in neighboring states.
Weather Interactions: Humidity keeps pollutants near the ground, and high humidity when there is no rain only worsens smog conditions.
Seasonal Trends: High humidity when temperatures are low and winds are light creates very severe episodes of pollution, especially at the time of festivals like Diwali when the pollutants are known to reach maximum levels.
#How does western disturbance influence air quality in Delhi.
Western disturbances have a significant impact on the air quality of Delhi. They do this mainly through impacts on wind patterns and precipitation:
Increased Wind Speed: Such disturbances often result in increased wind speeds, which help to spread out pollutants, thus enhancing air quality. For example, post a disturbance, wind speeds can increase to 12-15 km/h, assisting in the decrease of particulate matter concentrations.
Precipitation: Rain that is caused by western disturbances helps to wash away the air-borne pollutants. In case the disturbance is a weak one, the rain, as expected, will not be enough to considerably bring a difference in the quality of air.
Temperature Changes: The western disturbances may cause temperature fluctuations, thereby increasing pollution levels. Cold temperatures tend to trap the pollutants near the surface during the winter months.
Overall, while western disturbances can act as a temporary respite to pollution in Delhi, their role is largely dependent on the strength and accompanying weather conditions.
#What is the impact of rainfall on reducing air pollution in Delhi?
Rainfall plays an important role in reducing the air pollution in Delhi. It does so through several pathways:
Wet Deposition: Rain aids in eradicating particulate matter like PM2.5 and PM10 along with other pollutants within the atmosphere by washing out the air. As the drops of rain fall, it captures along with brings down aerosol particles by cleaning the atmosphere
Short-term effects: Air Quality Index (AQI) in Delhi largely decreases as soon as rainfall occurs in the city. For example, the most recent time, the previous severe conditions of AQI have easily been reduced to moderate over a short duration.
Short-Term Relief: Although rain brings relief from the pollution, its impact is always short-term. Pollution levels again rise after 48-72 hours of cessation of rain due to continuous emission and weather conditions.
In short, though rain is not a permanent solution, it is a natural mechanism that needs to be taken into consideration for controlling air pollution in Delhi.
#How does rain compare with other methods to reduce air pollution in Delhi?
Rainfall is a natural and effective method for reducing air pollution in Delhi, especially through the process of wet deposition, capturing and removing pollutants from the atmosphere. It immediately brings relief by washing away particulate matter and other harmful substances, which results in considerable improvement in air quality after a rain event.
On the other hand, cloud seeding through artificial rain aims to reproduce this phenomenon but remains under experimentation and skepticism concerning their effectiveness and long-term implications23. Similarly, technology-driven solutions include air purification equipment and dust suppression mechanisms, which can alleviate pollution to a certain extent but come at significant cost and maintenance requirements.
While rainfall provides a natural cleansing effect, sustainable solutions to combat pollution in Delhi should also address the root causes of pollution, such as vehicular emissions and industrial discharges, rather than relying solely on weather-dependent methods.
#What are the major challenges in implementing artificial rain in Delhi?
There are several significant challenges to implementing artificial rain in Delhi:
Weather Dependency: Successful cloud seeding depends upon the availability of appropriate clouds having sufficient moisture content, which during winter months is often lacking in Delhi due to prevailing weather conditions influenced by western disturbances.
Uncertain Results: Artificial rain is a practice that may or may not be effective. Not all clouds are amenable to seeding and, even if seeding happens, there is no guarantee that it will rain. The uncertainty in this regard does not make the method dependable as a pollution mitigation practice.
Short-Lived Relief: Short-term relief in the form of artificial rain is bound to wash away, giving temporary breathing space from dangerous air quality levels. According to them, long-term solutions that focus on abating sources are the keys to sustainable improvement.
High Costs and Resources: The cost implication of cloud seeding is very high. The costs range around Rs 1 lakh per square kilometer. This creates the question of whether the investments would be feasible or justifiable when considering the constraints.
Artificial rain in its current form might just present a temporary remedy; its execution in Delhi comes with various issues that warrant consideration of other more long-term means to deal with air pollution.