New Delhi: The stadiums have been renovated, the publicity posters hung. But not everything was ideal for players in the Under-17 World Cup being hosted in India, with air pollution beyond recognized safe levels in the six cities staging games.

In the hours before the first matches on Friday, levels of lung-clogging particulate matter known as PM2.5 hovered above 170 micrograms per cubic meter in New Delhi - or 17 times higher than what the World Health Organization deems safe, and more than four times higher than India's own standards.

Meanwhile, concentrations of PM2.5 in Mumbai were also considered unhealthy, registering in some places at 180 mcg per cubic meter.

The high levels are hardly surprising. At least 10 cities in India are among the world's 20 most polluted.

"If you apply World Health Organization standard as a measure, I think you'll find it difficult to hold any kind of international sports event in any city of India," said Anant Sudarshan, India director at the Energy Policy Institute of the University of Chicago.

Given the dangers air pollution poses to soccer players running hard on a field in 90-minute games, some of the six cities hosting games during the Oct. 6-28 tournament had plans for curbing pollution in the short term. The eastern city of Kolkata, which will host 10 matches including the tournament final, directed officials to monitor car emissions within 4 kilometers (2.5 miles) of the stadium and to police waste burning.

In New Delhi, where authorities warned that pollution would likely worsen over the weekend, environment ministry officials held a meeting to consider possible action.

Among the opening matches Friday, India was hosting the United States in New Delhi.

The air pollution menace, however predictable, raised little concern with officials at FIFA's headquarters in Zurich, Switzerland, according to Joy Battacharya, who heads local committee organizing the matches.

"We have not received any complaint from any participating player or official," Bhattacharya said in Kolkata.

Players and coaches appeared to be more concerned about preparations for their games than the conditions.

"Our full concentration is on football, and we do not get anyway affected with all this (pollution)," Colombia coach Orlando Restrepo told a pre-tournament news conference. "We do not want to give any excuses whatsoever. Nothing matters but just football."

India aims to highlight its potential to stage global events by hosting its first major international soccer tournament, hoping it will erase some of the embarrassment that overshadowed the scandal-plagued Commonwealth Games in New Delhi in 2010.

For the 24-team tournament this month, India spent 1.2 billion rupees ($18.5 million) in renovating stadiums in New Delhi, Mumbai, Kochi, Goa, Guwahati and Kolkata.

Those cities, however, "regularly break international standards" for air quality, according to a report by Greenpeace released Thursday.

The environmental group chronicled levels of coarse particulate matter known as PM10 during the same period last year, when air pollution starts worsening across much of India. Last year, it said, the capital averaged PM10 concentrations that were more than six times the recommended WHO limit of 50 mcg per cubic meter in October.

Levels of PM2.5 - even smaller particles that are particularly dangerous - spiked at times last October to 900 mcg per cubic meter - more than 90 times the WHO limit of 10 mcg per cubic meter, the report said.

"We're not asking for rescheduling or cancellation of the matches," said Sunil Dahiya, a Greenpeace campaigner who urged authorities to seek long-term solutions to clear the air. "Like the Chinese had during the Beijing Olympics in 2008, this can be our moment to seek comprehensive overhaul of our polluted air, on short-term and long-term basis."