As of December 6, 2021, over 5.2 million people have died from COVID-19, which has infected more than 266 million people globally. The Centers for Disease Control and Prevention (CDC) has issued a list of recommendations to protect against this virus, including social distancing, vaccinations, washing hands, and testing. In addition to these tactics, public health experts have recommended and, in some cases, mandated wearing masks to decrease transmission via respiratory droplets. The American Chemical Society estimates that people use 129 billion face masks per month around the world. These pieces of personal protective equipment (PPE) are critical to decreasing the spread of the virus, which was a top priority globally as the pandemic began. As we conclude the pandemic’s second year, it is time to shift our focus to confront the externalities of our pandemic response. Despite their importance for public health, disposable masks are causing widespread environmental harm.
Ocean ecosystems are being hit hard by disposable mask pollution. OceansAsia estimated that 1.56 billion face masks entered the oceans in 2020 alone, accumulating to between 4,680 and 6,240 metric tonnes of face masks. Similarly, Ocean Conservancy found that 94% of volunteers at the 2020 International Coastal Cleanup found PPE on shorelines during the cleanups for a total of 107,219 pieces in the second half of 2020. Once masks enter the waterways, they can harm marine organisms through entanglement and ingestion.
Most disposable masks are made of polypropylene plastics and typically take about 20–30 years to decompose completely. As disposable masks degrade, they can break down into microplastics and pollute water, soil, or air. A single mask can break down into 173,000 fibers per day when exposed to simulated seawater and ultraviolet light. Microplastics can also cause harm to organisms that ingest them through chemical toxicity. Once broken down to 1 millimeter, nanoplastics may enter cells and cause even more harm to organisms and their ecosystems.
Reusable masks initially seem to offer a better and more environmentally friendly option than disposables. However, public health measures must balance environmental benefits against human health impacts. A cluster-randomized trial in Bangladesh found that their selected multi-layer reusable masks filtered only about 37% of particles while high-quality surgical masks filtered closer to 95% of particles. Depending on their material, some reusable masks may filter as little as 5% of particles. While other reusable masks may have significantly higher efficacy comparable to medical-grade disposable masks, these are frequently more expensive or harder to access, leading millions of people to rely on disposable masks to protect themselves and their families. A potential policy solution would invest funding to develop inexpensive reusable masks. Additionally, governments could subsidize effective but higher-cost masks to encourage their use among individuals who may choose disposable masks solely for cost purposes.
In addition to more effective reusable masks, biodegradable masks could help decrease the pollution problem. Researchers at the Korea Research Institute of Chemical Technology (KRICT) have created mask filters from polybutylene succinate (PBS), a plastic resin that decomposes in just four weeks, and chitosan extracted from crab shells. These filters were highly effective during their initial study and removed 98.3% of fine particulate matter. KRICT also found that humidity did not negatively impact these filters, unlike some traditional mask filters. As with improved reusable masks, these biodegradable masks need more funding for research and development before they become a widespread alternative.
Many people will always use non-biodegradable disposable masks due to accessibility, affordability, or safety concerns. Therefore, the most immediate area to focus on may be disposal methods. Around the world, several groups have developed creative solutions for recycling masks into garden chairs, benches, shipping pallets, and flooring surfaces. TerraCycle has created a system to collect disposable masks for these projects, but recycling costs between $88 and $219 per box of masks returned. Because consumers currently face this financial burden, it is unlikely that many individual families or companies will participate. Governments adopting and funding these programs would be a great way to remove this cost from the public, encourage recycling of masks, and keep masks from polluting the earth. Having additional recycled materials for construction could also benefit manufacturing companies by easing the supply chain issues currently felt across many sectors.
Working to end the pandemic will also help decrease the number of masks and other medical supplies that harm the environment over the long term. On an individual scale, ending the pandemic can involve social distancing when possible, wearing masks, and getting vaccinated. On a broader policy scale, vaccine and mask mandates may have positive long-term environmental outcomes in addition to their public health benefits. While requiring masks may increase their short-term production and usage, ending the pandemic averts long-term pandemic pollution and is vital to ensure both human and environmental health in the future. Therefore, the expanded development and deployment of high-quality reusable masks and biodegradable disposables can further public health goals while protecting the environment from pandemic-induced pollution.
Developing better reusable masks, improving disposal methods, and ending the pandemic are all necessary to reduce long-term environmental harm. However, many other pandemic impacts still need to be studied. For example, COVID-19 induced a shift to single-use bags, cups, and takeout containers; increased glove or cleaning wipe usage; and other unforeseen consequences. As the pandemic continues to change globally, it is imperative to begin considering environmental impacts as we work to implement more effective public health solutions.