Right now, people in many parts of the world are just starting to experience the soaring temperatures that have become so common in recent summers. Nowhere is this more evident than in Israel, which is already experiencing its second heatwave of the season, with more certain to be the horizon. While that’s nothing new, and certainly something most people have learned to deal with, this year’s climbing temperatures present a unique challenge. That’s because this time around, they’re happening right in the middle of a pandemic.

With the coronavirus (COVID-19) still infecting thousands every day, people in every corner of the globe are already being asked to stay indoors in an attempt to control the virus’ deadly spread. But recent research is beginning to suggest that the very air-conditioned indoor environments that we rely on in the summer months might be contributing to the continuing pandemic.

According to Harvard professor Edward Nardell, there’s emerging evidence of a link between some of the surges in the transmission of the coronavirus in the southern US states and the increased time people are spending indoors. He says “The states that, in June, are already using a lot of air conditioning because of high temperatures are also the places where there’s been greater increases in spread of COVID-19, suggesting more time indoors as temperatures rise,” and that “As people go indoors in hot weather and the rebreathed air fraction goes up, the risk of infection is quite dramatic,”

That might be an ominous development for Israel, which is now beginning to reintroduce lockdowns as new coronavirus cases begin to spike again. It could mean that sending potentially infected people indoors at a time when they’re all but certain to require air conditioning might create the perfect conditions for additional transmission of the virus.

The good news, though, is that for the first time since the modern air conditioner hit the scene in 1902, there are some options available to decrease the risk of virus transmission in the recirculated air. Even better, they’re available in the form of retrofits that can be made to various types of HVAC systems.

The first and most common option is the addition of a HEPA filter to an existing HVAC unit. In most cases, such filters are available as replacements for existing owner-replaceable filters and don’t cost much more than OEM equivalents. Or, for systems that can’t accommodate HEPA-type filters, the addition of a MERV-13 or higher filter should offer a decent reduction in the amount of airborne virus particles circulating through the system.

The next option is the installation of a UV-C disinfection system to the ductwork of an existing HVAC system. They offer a somewhat new approach to killing viruses within recirculating air systems but have shown promising results. In some tests, UV-C fixtures installed in existing HVAC systems showed up to a 99.9% kill rate of airborne viruses. While there’s still no data available on how well they work against COVID-19, there’s every reason to believe that they’d have a beneficial effect.

And for those with split-unit HVAC or window air conditioning systems, the same type of UV-C fixtures are available in a wall-mounted form, so they can be used to clean recirculated air already in a room. They’ve been used to great effect in medical and veterinary facilities, and are considered as effective as the in-duct versions. And since they’ve been around even longer than inbuilt models, they do have a track record which includes killing other types of coronaviruses, like SARS and MERS.

So, as the summer heat continues to rise, the confining of populations to indoor spaces doesn’t have to become the source of more outbreaks. There are ways to try and reduce the risks of virus transmission within such spaces, provided that people take action to put them in place before it’s too late. All that’s needed is some proactive action on the part of homeowners and building managers to upgrade their HVAC systems. And as the southern US states continue to present a cautionary tale of what might be soon coming to Israel, now would be a good time for Israelis to take heed and try to avoid suffering a similar fate as the mercury climbs.