The Broken Jet Stream Behind NYC’s Smoke Invasion

Ethan Steininger
5 min readJun 8, 2023


Today, New York City was cloaked in a hazy shroud. The reason? Wildfires raging in Ontario, Canada. Usually, prevailing winds would carry the smoke eastwards over the Atlantic, but this isn’t the case now. The wind is blowing in a different direction, carrying the smoke southwards instead, resulting in the suffocating haze hanging over NYC. The unusual scenario can be traced to a disruptor high in our skies: the jet stream.

The Broken Jet Stream and Smoke Accumulation

Jet streams are fast-flowing, narrow air currents in the Earth’s atmosphere that help regulate the planet’s climate by balancing heat and cold and determining the direction of the wind. However, climate change has impacted this crucial system, leading to what scientists refer to as a ‘broken’ jet stream. This disruption has made the jet stream’s flow more erratic, resulting in weather extremes, and in this case, a significant redirection of smoke from Ontario’s wildfires towards NYC.

The ‘broken’ jet stream has been causing loops and waves in the air currents, pushing the smoke south rather than east. As the smoke travels, it carries with it particulate matter, hazardous pollutants, and gases, all of which significantly contribute to air pollution.

Impact on Air Quality Index (AQI)

The New York Department of Environmental Conservation measures the Air Quality Index (AQI) based on the concentration of pollutants in the air. The accumulation of smoke from Ontario has resulted in a significant spike in AQI levels, which have now risen to the ‘unhealthy’ range. This means that every New Yorker, especially those with respiratory conditions, are at risk.

Reduced Controlled Burns

Controlled or prescribed burns have long been a tool utilized by forest management to reduce the build-up of combustible materials and decrease the likelihood and intensity of wildfires. By deliberately setting small, manageable fires under controlled conditions, forest managers can reduce the accumulation of deadwood, leaves, and other flammable material that provide fuel for wildfires.

Unfortunately, in recent years, controlled burns have been significantly reduced in many regions, including Ontario. This reduction can be attributed to various factors such as budget constraints, potential risks, and public perception issues. Reduced controlled burns have led to an accumulation of combustible material that has transformed forests into tinderboxes, primed for ignition.

This build-up of dead wood, coupled with an increase in gases produced by decaying matter, has created perfect conditions for larger, more intense wildfires. These wildfires are not only harder to control, but they also generate considerably more smoke than smaller, controlled burns.

Mitigating the Impact with HEPA Filters

In the face of these conditions, one practical way for residents to protect themselves indoors is to use High-Efficiency Particulate Air (HEPA) filters. These filters can trap 99.97% of particles that are 0.3 micrometers in diameter, helping to clean the air inside homes and offices. It is recommended that those particularly vulnerable, such as the elderly, children, and individuals with respiratory conditions, stay indoors as much as possible and utilize HEPA filters.

Smoke Particles and Outdoor Protective Measures

The smoke generated by wildfires consists of a complex mixture of gases and fine particles produced when wood and other organic materials burn. The particulate matter, PM2.5, contains particles that are 2.5 micrometers in diameter or smaller. To put it in perspective, these particles are approximately 30 times smaller than the diameter of a human hair. The small size of these particles allows them to be easily inhaled, posing a significant health risk.

While staying indoors is the best way to reduce exposure to PM2.5, it may not always be possible. If you must venture outside during periods of poor air quality, wearing a mask can provide a measure of protection.

However, not all masks offer the same level of protection against wildfire smoke. Ordinary dust masks, bandanas, and surgical masks are not effective in filtering out the microscopic particles in wildfire smoke.

N95 and P100 masks, on the other hand, are designed to filter out 95% and 99.97% of airborne particles, respectively. These masks, when properly fitted, can provide substantial protection against PM2.5. Moreover, masks with the rating of KN95, often more readily available, can provide similar protection to N95 masks.

Hope for the Future

While the current situation may seem grim, there’s reason for hope. Climate scientists and meteorologists are working together to better understand and predict the behavior of the jet stream. This collaboration could eventually lead to more effective ways to mitigate its impacts on weather patterns and air quality.

Moreover, as our understanding of climate change deepens, so does our capacity to combat it. The ultimate solution to the broken jet stream and other climate change effects lies in reducing our greenhouse gas emissions. There is a global push towards cleaner, more sustainable energy sources, which can help us stabilize our climate and restore the natural systems, like the jet stream, upon which we depend.

The unusual southward drift of Ontario’s wildfire smoke serves as a stark reminder of the intricate connections within our climate system. The broken jet stream has shifted the direction of the smoke, turning a typically eastward problem into a southern issue. This unexpected change underlines the urgency for global action to combat climate change and protect the vital systems that maintain our planet’s equilibrium.