Experts say that rapid industrialisation coupled with weak enforcement of environmental laws have played a role in increasing pollution in the country.<br /><br />India has seen a lot of development in the past few decades, but poor industrial regulation means that factories do not follow pollution-control measures. Rapid construction has also contributed to rising levels of pollution.<br /><br />The report by IQAir said that India's average level of PM2.5 - fine particulate matter that can clog lungs and cause a host of diseases - was 54.4 micrograms per cubic metre.<br /><br />Globally, air that has 12 to 15 micrograms per cubic metre of PM2.5 is considered safe to breathe, while air with values above 35 micrograms per cubic metre is considered unhealthy.<br /><br />Delhi's air quality was worse than India's overall air quality with the city having a PM2.5 reading of 92.7 micrograms per cubic metre.<br /><br />Delhi struggles with bad air around the year, but the air gets particularly toxic during winter.<br /><br />This happens due to various factors, including burning of crop remains by farmers in nearby states, industrial and vehicular emissions, low wind speeds and bursting of firecrackers during festivals.<br /><br />Last year, the government shut schools and colleges for several days in a row due to the toxic air.<br /><br />Meanwhile, the northern Indian city of Beguserai and the northeastern city of Guwahati were ranked as the two most polluted cities in the world.<br /><br />Only seven countries met the World Health Organization (WHO)'s annual PM2.5 guideline, which is an annual average of 5 micrograms per cubic metre or less.<br /><br />These include Australia, New Zealand, Iceland and Finland.<br /><br />According to IQAir, this data was gathered from more than 30,000 air quality monitoring stations positioned in 134 countries, regions and territories.<br /><br /><br /><br />Delhi world's 'most polluted' capital: report<br /><br /><br /><br /><br />
