Philadelphia's restaurants can expand indoor dining capacity to 50% starting Friday if their ventilation system allows enough air to circulate, city leaders announced Tuesday.

Restaurant owners will have to self-certify that they meet air quality standards - including replacing the room's air at least 15 times an hour.

"Now if they don't have an HVAC system they can still do this, what they need to do is put fans in the windows. We will be giving them guidance on how they can do that," Health Commissioner Dr. Thomas Farley said.

For the form, linked above, a restaurant employee or HVAC technician will need to measure the airflow of the restaurant's air system and submit it to the city. The city will allow restaurants to expand their capacity based on what they report on the form. The health department has a goal of responding within 72 hours after a business submits its documents.

"We do think this is a way to try to have restaurants get back on their feet economically, to provide service to customers, while also doing it safely. We're trying to come up with that balance," Farley said.

Besides the requirement of 15 air exchanges per hour, here are the other required air standards, according to the city:

• For HVAC systems, circulating at least 20%
• A MERV 11 or better air filter in the system
• An exhaust vent at least 6 feet from tables and chairs

For restaurants using window fans, they need only exchange the air 15 times per hour.

Restaurants that meet the air standards will be allowed to up their indoor capacity. The city will check those numbers if there is a complaint about the restaurant.

Farley called the air standards "version 1.0" and said they may be adjusted as the plan is underway.

11:59 p.m. Tuesday is the deadline for restaurants and gyms to apply for a city grant of up to $15,000 if they experienced hardship in the pandemic. More information is on the city's website here.