In photos, it's hard to make out Hong Kong through the thick, gray haze.

Smog, made worse by winter weather conditions and wind, has blanketed the city. The coastal skyline is barely visible, and ships in the region's busy harbor appear veiled like ghosts.

According to World Air Quality Index, the city is experiencing unhealthy levels of air pollution. This assessment is based on hourly measurements of pollutants like particulate matter and carbon.

Conditions aren't expected to significantly improve until later in the week, but sensitive groups like those with chronic conditions or the elderly may still be at risk of respiratory issues.

According to reporting by news agency AFP, residents that venture outside are finding the air difficult to breathe in.

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