Can Delhi’s Odd-Even Policy Help in Preventing Health Issues?

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Can Delhi’s Odd-Even Policy Help in Preventing Health Issues? Blog Image

Why in News?

  • In the view of rising air pollution in New Delhi, the Delhi government announced the odd-even rule from November 13 to 20.
  • There is certain data suggesting that the adoption of an odd-even vehicle restriction measure can lower pollution levels, particularly during daylight hours.
  • However, experts say that the existing evidence lacks uniformity, and the resulting decrease may not be adequate in effectively mitigating health-related consequences.

The Concept of Odd-Even Formula

  • First implemented by the Delhi government in 2016, the odd-even program permits private vehicles to be used on a rotational basis, determined by the final digit of their number plate.
  • As per odd-even rule, vehicles with license plate numbers ending in an even digit are authorised to be on the road during even dates, whereas those ending in odd digits can be driven on odd dates.

An Analysis of the Impact of Delhi’s Odd-Even Rule

  • Not a Long-Term Solution
    • Experts believe that odd-even is not a long-term solution because with several exceptions, odd-even does not really cut the number of vehicles plying on the roads by 50%.
    • More importantly, the reduction in emissions does not always mean a reduction in the pollutant concentration in the air, as that depends on meteorological factors like wind speed.
    • The evidence so far shows an uneven impact; while some areas have seen reductions, others have not, or the reduction has been only for a few hours.
  • No Studies to Show the Impact on People’s Health
    • There is no study to show whether this small reduction in air pollution levels impacts people’s health.
    • Doctors at AIIMS, Delhi say that when the PM2.5 levels are over 500, a 20% decrease would mean a drop to only 400. That is still very harmful.
    • Long-term exposure to pollution is associated with increased risk of hypertension, diabetes, and cardiovascular diseases like heart attacks and strokes.
    • It is known to increase the risk of chronic lung diseases, cancers, lower immunity, and also leads to depression.
  • Very Meagre Decrease in Particulate Matter
    • Several studies have shown a decrease in the level of particulate matter when the odd-even scheme is in effect in Delhi. This reduction, however, has only been around 5 to 10%.
    • A study of the 2016 implementation of odd-even using satellite data found a 2 to 3% decrease in PM2.5 concentration in most of Delhi, except three pockets where it went down by 8 to 10%.
    • Another study from Delhi Technical University found a 5.73% reduction in PM2.5 levels on average and 4.70 % in PM1.
      • The studies said that the lower PM levels could be because of fewer cars, and also because of traffic moving faster on decongested roads and engines idling less.
      • The studies noted that the sharpest drop in PM levels was observed during midday and not early morning, when the cold temperatures keep the pollutants suspended close to the ground.
    • Another study by scholars from IIT Delhi and two UK colleges compared PM levels in 2016, when odd-even was implemented, with the same period the previous year.
      • It found that 5 ranged from -2 to -44 % from the previous year during odd–even hours, but was higher by 2–127% during non–odd–even hours.
  • Reduction of NO2 (Nitrogen Dioxide) Emissions
    • There could be one important benefit from the odd-even scheme.
    • With fewer vehicles on the road and less congestion, gaseous pollutants such as nitrogen dioxide, primarily coming from vehicular emissions, would also reduce.
      • This is important because a recent research study conducted by AIIMS revealed that there was a greater rise in emergency room visits associated with elevated levels of NO2 compared to PM2.5.
      • Short-term exposure to NO2 resulted in a 53% surge in the number of individuals seeking care at the hospital's emergency room within a week.

What Needs to Be Done?

  • Work on Long-Term Solutions: As for long-term solutions, measures such as phasing out BS-IV vehicles and bringing in more electric vehicles are likely to show results in the coming years.
  • Expand the Scope of Odd-Even Geographically: Measures like odd-even should be implemented in a regional manner and not in Delhi alone.
  • Strengthen Governance with Every Stakeholder to Ease the Pollution Level
    • Delhi's Graded Response Action Plan (GRAP) activates anti-pollution measures based on air quality levels and should be replicated in other Indian cities.
    • Real-time industrial pollution monitoring is essential. Communities should oversee urban spaces, preserving them from private interests.
    • Efforts like smog towers and watering roads are futile solutions to pollution. True progress lies in empowering people through effective governance.
    • Pollution guidelines and standard procedures should be accessible and integrated into daily life.
    • Enforcing measures, like the odd-even plate system or a 'no-car day,' requires strong governance and public support.


  • Studies and research suggest that while the odd-even rule in Delhi may help in less vehicular movement and a slight change in emissions, its impact on curbing pollution is negligible.
  • Short term remedies like odd-even rule will have no impact, neither on city’s pollution nor on people’s health, in long run.
  • The government of Delhi and state governments of Haryana and Punjab must work together and work on long-term solutions.

Q1) What is air pollution and its causes and effects?

It is the contamination of air by harmful gases, dust and smoke which affects plants, animals and humans drastically. There is a certain percentage of gases present in the atmosphere. An increase or decrease in the composition of these gases is harmful to survival.

Q2) What is the difference between PM2.5 and PM10 particles?

Dust from roads, farms, dry riverbeds, construction sites, and mines are types of PM10. Coarse (bigger) particles, called PM10, can irritate eyes, nose, and throat. Fine (smaller) particles, called PM2.5, are more dangerous because they can get into the deep parts of lungs or even into blood.

Source: The Indian Express