Record breaking PM2.5 pollution levels in NYC in early June 2023 regular occurrence in over 350 cities worldwide

The first week of June 2023, New York City saw some of the worst air pollution on record as levels of harmful PM2.5 particles skyrocketed due to smoke from wildfires in Quebec, Canada. Within days, the air quality had returned to “good”, according to IQAir.

Data from the Centre for Research on Energy and Clean Air (CREA) shows that, globally, at least 350 cities have had at least one day of worse PM2.5 pollution compared to NYC this year due to the burning of fossil fuels. The most polluted cities have had more than 50 such days.

New York City’s record-breaking air pollution episode 

Last week, air pollution levels in New York City broke city records and exceeded guideline values set by the environmental and health agencies. On Wednesday, 7 June 2023, measurements of daily-average PM2.5 in New York City reached a record breaking 117 μg m-3. This value exceeds the previous New York City record (86 μg m-3), is three times higher than the guideline value set by the US Environmental Protection Agency (EPA) (35 μg m-3), and is over eight times higher than the guideline value set by the World Health Organisation (WHO) (15 μg m-3). 

Once inhaled by humans, PM2.5 can lead to a wide variety of health illnesses, including ischaemic heart disease, chronic obstructive pulmonary disease, and lung cancer, lower respiratory infections, diabetes, premature mortality, dementia, Alzheimer’s, and depression. Each year, exposure to this pollutant leads to over 3,000 premature deaths in New York City

New York City’s air pollution episode last week was due to wildfires hundreds of kilometres away. Wildfires in Quebec (Canada) lead to the emissions of PM2.5, which can persist in the atmosphere for 1-2 weeks. Due to the weather conditions, the PM2.5 from Quebec was transported southwards, where it affected air quality throughout the East Coast of the US. If humans continue to emit greenhouse gases, the risk of wildfires in the US could increase by up to a six-fold by the end of the century. 

New York City’s air pollution episode has captured the attention of the public, media, politicians, and scientists. Post-apocalyptic pictures of the iconic New York City skyline have gone viral. Discourse has been ignited among residents, including sharing methods for protecting themselves against pollution. The episode has been covered extensively by the media, both nationally and internationally. Scientists have run models to forecast the trajectory of the pollution plume from Canada. Government agencies, such as the state governor and health commissioner issued advice, including shutting down schools,  remaining indoors, and wearing a mask.

Overall, the huge response to the air pollution episode in New York is in-line with the severity of the public health crisis, and the general public, media, and political officials have rightly acknowledged the origins of this pollution, and how it is affected by human activity. Because of this, residents have been able to minimise their exposure to the pollution, and governments are able to address the underlying cause of this issue. However, this environmental and public health crisis is not only confined to New York City.

A global perspective of air pollution episodes

CREA’s research reveals that the daily-mean value of PM2.5 recorded in New York City last week (117 μg m-3) has been exceeded globally in at least 350 cities already in 2023. Figure 1 shows a map of PM2.5 measurement sites, where sites that have at least one day exceeding 117 μg m-3 are shown in red, and sites where no days exceed 117 μg m-3 are shown in blue. Most cities that have recorded an of exceedance of 117 μg m-3 in 2023 are in Asia, followed by Eastern Europe, the Middle East, and Africa. In these regions, one of the dominant sources of PM2.5 is the burning of fossil fuels. While very few exceedances are detected in some developing regions that are also reliant on fossil fuels, such as South America and Africa, this is largely a reflection of the lack of measurement stations, which are expensive to set-up and run.

Figure 1 – PM2.5 measurement sites
Sites that have at least one day exceeding 117 μg m-3 are shown in red, and sites where no days exceed 117 μg m-3 are shown in blue.

From CREA’s database of measurements, we calculated the number of days that the daily-average value 117 μg m-3 was exceeded, and the top 30 cities are shown in Figure 2. Cities in Pakistan suffered from the highest number of days that exceeded 117 μg m-3 , followed by Bangladesh, India, Thailand, Chad, China, Tajikistan, and Uzbekistan. In the cities in Pakistan for which we have measurements, the daily-average value of 117 μg m-3 is exceeded almost every other day.

Figure 2 – Top 30 cities with daily-average value of PM2.5 exceeding 117 μg m-3

While these cities suffer from air pollution levels even worse than those encountered in New York City, the response by the media and public officials is starkly different. Oftentimes, air pollution episodes in these cities are rarely covered by the national or international media. Scientists and public officials deny the presence and impacts of air pollution, including India’s Union Environment Minister Prakash Javadekar, and Poland’s Energy and Health Ministers.

A future free from pollution and climate change 

From this analysis, CREA has identified several responses to New York City’s air pollution episode that correctly contribute to minimising the health risks from this event, and preventing the event from occurring in the future. This analysis has also identified several places around the world that could benefit from implementing these responses in their air pollution episodes, namely Pakistan, Bangladesh, India, Thailand, Chad, China, Tajikistan, and Uzbekistan, and the responses include the following:

  • The public and media must not allow public officials to deny the impacts of air pollution, which have been established by decades of scientific research.
  • Environmental and public health officials must respond to air pollution episodes in-line with the severity of the health risk, and correctly identify how human activities have contributed to it, and how they can change in the future to minimise its frequency.
  • Media outlets need to expand their coverage of air pollution, recognising that it is both an environmental and public health crisis that is affecting millions of people worldwide.
  • Air pollution monitoring needs to be expanded so that the environment and health of low-income communities can also be protected.

As fossil fuel combustion is a major source of both air pollution (e.g. PM2.5) and greenhouse gas emissions, reducing this activity and switching to renewable energy can minimise the impacts of climate change (e.g. wildfires) and improve air pollution, therefore improving the health for all life on Earth.

This analysis was prepared by Jamie Kelly, Air Quality Analyst, CREA; and Lauri Myllyvirta, Lead Analyst, CREA
These graphs are based on CREA’s Air Quality Data Portal. The Air Quality Data Portal aggregates air quality from dozens of official data sources. Find the portal and more data products here.