California cities need to more clearly communicate how and when to use masks consistently and effectively, including the use of N95 and high-filtration, or hi-fi, mask alternatives. As vaccines are expected to take several months to reach herd immunity, hi-fi masks provide interim protection from COVID-19 and its mutant strains, such as B.1.1.7, which are reported to be more transmissible and more deadly.

Los Angeles County residents are needlessly dying because hospitals lack intensive care unit capacity. The ICU scarcity is also happening in the Bay Area, but to a lesser degree, despite both areas being in the same state and having similar temperature and humidity, both of which have been hypothesized to impact viral spread.

Although statistics on COVID-19 testing are reported daily by municipal governments, even months after mask mandates the percentage of people wearing masks correctly in California cities is neither tracked nor reported reliably, as reflected by its absence in dashboard indicators for San Francisco or Berkeley. This means it is next to impossible to make intercity comparisons of mask utilization that are vital to slowing the spread.

In July, the Los Angeles Times found that only 42% of people walking in three Los Angeles and Orange County locations were correctly wearing masks. Using the same data collection method in the Bay Area and greater Los Angeles area, my organization Patient Knowhow, which researches hi-fi mask options, looked at publicly accessible street cameras in busy intersections to see how many people were even wearing masks. By counting more than 100 people in each area, in January I observed that 91% of people walking on Castro Street in San Francisco were correctly wearing masks compared to only 60% of people at Hermosa Beach in Los Angeles. Just as statistics on COVID-19 testing are reported daily, street level video cameras can be utilized to cheaply and systematically track compliance rates with mask mandates and nudge city residents to comply by making numbers public.

An underutilization of masks means that Los Angeles, and other cities with the means to measure it, have that much opportunity to flatten the curve with public awareness interventions to increase usage. In the next seven days, cities such as Los Angeles with a low rate of mask usage can kick off a vigorous public awareness campaign by publishing the daily percentage of community members using masks, setting a target of mask usage exceeding 90%.

San Francisco and other cities with high mask adoption can do more too. According to the Centers for Disease Control and Prevention, the main way COVID-19 is transmitted is via inhalation of respiratory droplets or aerosols, which are only known to be reliably blocked by N95 masks, better when worn with a good fit. San Francisco has a long-standing policy to distribute N95 masks to populations at the highest risk, such as unhoused residents, but only during wildfire smoke emergencies. Given that San Francisco’s infrastructure is already set up to support its residents by distributing masks and that herd immunity will take months to attain, cities such as San Francisco should expand the “N95 umbrella” to elderly people, essential workers and other vulnerable groups, as well as everyone in their bubble.

Experts have suggested that if everyone in the country wore N95 masks for four weeks the pandemic would end. Every elected official should ensure their residents are using N95 masks or hi-fi alternatives such as elastomeric or surgical masks with a fitter.

Cities must also inform residents to ensure masks are fitted properly. Without a proper fit, unfiltered air leaks around the edges of any mask without tight contact around the face. The fit of commonly used surgical masks can be improved with “fitters” such as Fix The Mask to enhance the filtration of viral particles.

Currently, disposable N95s are officially reserved for health care workers because of high demand since the start of the pandemic. Rather than being exclusively reserved for hospitals, demand for N95 masks from consumers can be complementary if this demand is fulfilled as a second priority in between hospital orders. This improves the resilience of the N95 supply chain by evening out the fluctuating demand from hospitals and keeping these manufacturers in business. However, N95 users need to be trained to achieve a proper fit.

In addition to disposable N95 masks, a National Institute for Occupational Safety and Health-approved class of N95 masks that is not in short supply is an elastomeric N95, or eN95, which several organizations, including the New York City Fire Department, are now using. In addition to being reusable, the eN95 has some distinct advantages such as stretchy surfaces and straps that can achieve a better fit and lower leakage, according to the CDC.

In the next seven days, the state of California and its major cities should immediately begin to do two things. First, cities should measure and publicly report mask utilization weekly (if not daily) by neighborhood to diagnose and target public awareness interventions where they are needed the most. Second, cities should ensure residents have access to readily available hi-fi masks. It is up to our community leaders to ensure better public mask usage in order to flatten the curve.