Over the holidays, I visited my relatives in New Delhi, India. While there are few things I would have traded this experience for, I was reminded that I was in the most polluted city on earth whenever I looked up at the hazy, dusty sky.The air in New Delhi regularly has a PM2.5 ranking above 300 micrograms per cubic meter. PM2.5 rankings, or fine particulate matter rankings, are standards used to measure the concentration per cubic meter of air particles that span no more than 2.5 micrometers in width. High numbers of such aerial particles can pose serious health risks to people that breathe them in overtime.

The United States Environmental Protection Agency (EPA) found that New Delhi's PM2.5 levels fall under the "very unhealthy" or "hazardous" categories. Delhi's pollution levels can pose a higher risk of heart disease, chronic bronchitis, and lung cancer to its entire citizen population, according to the World Health Organization.

As more and more people realize the risks the come with high pollution, the Indian authorities have been pressurized to combat pollution itself. Many projects have been initiated to eliminate electricity waste, to build solar panels, and most recently, to limit traffic.

On January 1st, the chief minister of Delhi, Arvind Kejriwal, enacted his famed "Even-Odd Plan". The plan allowed only cars with license plates ending in even numbers to travel on certain days. On the other hand, it allowed only cars with license plates ending in odd numbers to travel on other days. Violators of these simple rules would be fined. In theory, the policy should have cut traffic in half. In many areas, it was successful in reducing the number of cars on the road.

But, the even-odd rule did not come without flaws. Some residents pointed out that since the policy was implemented, traffic jams were not eliminated and instead became more frequent in some satellite cities of New Delhi, like Gurgaon and Noida. Moreover, scientists agree that the plan seems to have made little progress in fulfilling its primary purpose: to lower pollution.

Others complained that the rule favored certain populations. It catered to women by exempting them from some of the restrictions. This exemption is understandable because shared vehicles can be considered especially unsafe for women in some parts of Delhi. The plan also excused taxicab and Uber drivers. They gleefully reported record-high demand for their services. Perhaps they benefited from the policy because a major percentage of them are ardent supporters of Arvind Kejriwal's political party, the "Aam Aadmi Party" (AAP).

The even-odd policy officially ended on January 15th. On that day, Kejriwal tweeted, "Proud of u Delhi. U give me confidence. Together, we can achieve anything. 1st phase of Odd Even ends today. Will do again in improved form." Since the termination of the even-odd policy, Delhi newspapers have noted that traffic levels have increased substantially.

Kejriwal's efforts to combat heavy traffic are not the first. In 2003, officials in London lowered high levels of traffic by imposing higher fees on vehicles entering the city via certain routes. Like they did in Delhi, road control measures in London initially encountered political resistance. But, in the end, these London "congestion charges" eventually brought the traffic down to acceptable levels, thereby increasing everyone's productivity.

Similarly, France instituted an even-odd program for just one day in its capital on March 17th, 2014. The policy was mainly intended to lower traffic and smog levels. French officials claimed that their policy was followed by almost 90% of the population and that it accomplished its goal. Some Parisians, particularly the lower class ones, were severely inconvenienced by the plan.

Perhaps the biggest difference between Delhi's traffic control measures and London's or Paris's was the effectiveness of the law enforcement involved. In theory, violators of Kejriwal's policies should have been fined 2000 rupees (~US$30). While law enforcers were ever-present at busy intersections, Delhites could easily disregard the even-odd rule if they traveled in certain areas. This was not the case in either London or Paris, where close to 100% participation was met.

Traffic control is necessary as countries become more industrialized because traffic jams are ultimately a sign of economic activity. We witness them in the most bustling cities of our world. Even so, there is an economic loss in productivity that comes with congestion. Forbes reports that in 2013, traffic jams had cost Americans alone $124 billion. Those figures are projected to rise, especially in developing countries, where more and more people are buying their first cars.

The only option for the time being is to continue to explore new methods to handle an increasingly mobile global population. The key to traffic reform is to create plans that are tailored to specific regions. While Kejriwal's even-odd policy was heavily criticized, similar policies will likely have to enacted and constantly adapted across our changing world.