Fewer first responders will be available for the usual spike in firework incidents and ER visits during July 4th weekend — one of America's most dangerous holidays

• On average, more Americans visit the emergency room on July 4 and 5 than any other day during the year, making it "by one measure, the most dangerous day of the year," according to the Pew Research Center.
• First responders are already stretched thin by the coronavirus pandemic, leaving some cities and towns worried about this year's Independence Day holiday, particularly when it comes to ER visits and the availability of first responders.
• In Houston, a reported 307 firefighters are in quarantine for COVID-19 on the morning of July 4, leaving the department close to 100 short of a usual holiday shift, according to the local ABC affiliate.

A double whammy of the coronavirus and a typical surge in emergency room visits around the US Independence holiday is leaving local governments with tough decisions in emergency management.

Both July 4 and 5 see the highest single-day ER visits in the US annually, according to data from the National Electronic Injury Surveillance System (NEISS).

Fireworks-related injuries stacked on top of the usual accidents that land people in the ER — not factoring in the coronavirus — have made the 4th of July "by one measure, the most dangerous day of the year," according to a Pew Research Center study.

Areas battling surges in the coronavirus are particularly vulnerable to this confluence of events over the holiday weekend.

In Houston, more than 300 firefighters are in quarantine because of potential exposure to COVID-19, leaving the department close to 100 short of a full force for the holiday shift.

Houston is seeing record numbers of new cases, with a local health expert warning it could become the "worst affected" city in the nation.

On Friday, the Houston Professional Fire Fighters Association sent out a news release indicating triage measures — such as closing down some stations — may have to be put in place for the holiday given the staff shortage.

A call to the Houston Fire Department's public information line from Insider went unreturned.

Other areas are bracing for a confluence of factors in addition to other variables, such as wildfires.

In California, fire departments are bracing for the knock-on effects of legal and illegal fireworks as the wildfire season kicks into gear.

"Nobody ever sets off a firework going, 'Hey, let's set the mountain on fire. Let's disfigure a child,'" Eric Sherwin, a San Bernardino County firefighter, told the local CBS affiliate.

The US Consumer Product Safety Commission has guidelines for firework safety to prevent injuries, which can mount to almost 5,000 just within the first eight days of July.