Hong Kong’s air pollution may today reach “serious” level, the worst rating, as light winds fail to disperse smog, the government said. The current health risk from pollution is “very high,” the government said in an e-mailed statement. A serious rating means pollution as measured by the Environmental Protection Department reached a scale of 10-plus. “Intense sunshine has enhanced photochemical smog activities and the formation of ozone,” the government said. “The ozone is also being accumulated due to light winds, resulting in higher pollution levels.” Poor roadside air quality represents the biggest daily health threat to Hong Kong’s 7.2 million people, according to the government’s clean-air plan published last year. Nitrogen dioxide, mostly formed from vehicles in roadside areas, has been linked to damaged lung function in children and asthma attacks. Air quality monitoring stations in the city were registering ratings from 6 to 10 as of 4:07 p.m. local time, according to data on the environmental bureau website. This will be the fourth time this month that air pollution reached the serious level. Air quality has worsened in the city between 2007 and 2013 because of increased emissions from vehicles and ships.