While Beijing residents continue to struggle through a period of unusually high air pollution, similarly high smog levels are a fact of life for many in different parts of the world, where Beijing-style warning systems aren't in force. In the past week, during which Beijing's air pollution has been at its most severe, air quality has been 150% worse in Delhi, India's capital.

These figures are based on the particulate matter, or PM 2.5 levels, in both cities. '2.5' refers to the particles' diameter of 2.5 micrometers or less. These tiny particles are considered to be the most deadly, as they penetrate much further into the lungs than larger pollution particles - seriously increasing the prevalence of respiratory diseases and the risk of lung cancer.

Hindustan Times reports that, in the last week, the air in Delhi has had an average PM 2.5 concentration of 230.9 micrograms per cubic meter. By contrast, the average in Beijing over the same period was 139.8 micrograms. The analysis is based on a comparison of data generated by IndiaSpend's #Breathe air quality monitoring sensor placed at RK Puram, Delhi with the one placed by the US government in its embassy at Beijing. The PM 2.5 concentration level in Delhi has been higher than Beijing for six out of seven days under consideration, based on a comparison of daily averages.

According to Independent, both cities have seen unusually high pollution levels recently, resulting in schools and businesses being shut down in Beijing as local authorities try to protect residents. Delhi and other cities do not have a similar alert system as Beijing - leaving schoolchildren and workers to bear the brunt of the pollution without much protection. The average annual PM 2.5 level in Beijing is around 56. That's still far higher than the World Health Organization's healthy rating of 25, but much lower than Delhi's annual average of 153.

According to the data, Delhi only sees two days of fresh air each year on average, while Beijing has 42 such days. Extreme pollution levels are recorded in Delhi for eight months a year, as opposed to three months for Beijing

India Today says that, on December 8, 2015, officials in Beijing ordered schools to close down and have also asked for a halt in the other outdoor construction activities from 7 AM on December 9 to noon on December 10.

During this period, cars will be allowed to drive only on alternate days, depending on their license plate numbers. A similar measure announced by Delhi Chief Minister, Arvind Kejriwal, is being debated by lawmakers and civil society, with doubts being raised regarding the effectiveness with which the formula can be executed. It is worth noting here that when the odd-even formula for private cars was enforced in Beijing for a two-week period starting August 20, 2015, the city's usually smog-filled skies had turned perfectly blue.

Greenpeace India, while releasing a survey on indoor air quality in Delhi schools recently, said that the pollution levels were found to be five times more than the safety limits. Another report by Kolkata-based Chittaranjan National Cancer Institute (CNCI), says that nearly half of the Delhi state's 4.4 million school children are growing up into adults with irreversible lung damage.  

Every time Delhi's worsening air pollution is discussed, China is often mentioned in the same breath. Although, WHO data reveal that Delhi has the world's worst air pollution with the highest PM 2.5 concentration levels among cities. Beijing, by comparison, is not even in the top 50 cities by air pollution.