Forget free wine hours and on-demand workout videos. An increasing number of hotels around the world are now providing guests the option to book rooms with filtration and purification systems that minimize threats of air pollution and offer cleaner air.

“Interior air quality can be abysmal,” said Beth McGroarty, research director for The Global Wellness Institute, a nonprofit organization for the wellness industry. “Hotels are combating this by installing high-tech systems in some of their rooms that improve the air their guests are breathing.” The quest for clean air is part of the growing interest in wellness travel, Ms. McGroarty said .

Outside conditions could certainly be a larger factor. According to data released last year by the World Health Organization, nine of 10 people globally breathe polluted air. Many top urban destinations, particularly in developing nations, have been recognized for unhealthy smog conditions. Wildfires are becoming more frequent, affecting the air quality of hundreds of miles. And travelers with respiratory conditions or allergies may especially benefit from breathing cleaner air.

Most hotel properties generally charge a higher nightly rate for their clean air rooms, compared with their standard rooms, and while the amount varies depending on the hotel, a stay can be 5 percent to 7 percent more expensive.