A person struggling to breathe in a polluted city.

Can Air Pollution Trigger COPD Flare-Ups? What You Need to Know

Theo Raines in Health & Wellness November 2025 • 4 min read.

"A new study investigates the link between common air pollutants like benzene and toluene, and emergency COPD hospitalizations. Find out what it means for your respiratory health."

Chronic Obstructive Pulmonary Disease (COPD) is a major global health concern, significantly impacting quality of life and contributing to millions of deaths annually. While smoking is widely recognized as a primary cause, the role of air pollution is increasingly coming under scrutiny.

Most research has focused on the well-known criteria air pollutants. However, less attention has been given to volatile organic compounds (VOCs) like benzene and toluene, which are commonly found in urban environments. These pollutants often coexist, raising concerns about their combined impact on respiratory health.

A recent study conducted in Hong Kong aimed to investigate the short-term effects of benzene and toluene on emergency COPD hospitalizations, providing valuable insights into the potential risks associated with these often-overlooked pollutants.

Benzene and Toluene: Hidden Threats to COPD Patients?

A person struggling to breathe in a polluted city.

The Hong Kong study utilized a time-series approach, analyzing daily data on emergency COPD hospitalizations alongside air quality measurements. This method helps to minimize the influence of factors that don't change over time, such as smoking habits and socioeconomic status, allowing researchers to focus specifically on the impact of air pollution.

Researchers collected data on daily concentrations of benzene and toluene from Hong Kong's Environmental Protection Department, alongside daily counts of emergency COPD hospitalizations from the Hospital Authority. Statistical models were then used to estimate the percentage excess risk (ER%) of COPD hospitalizations per interquartile range (IQR) increase in ambient benzene and toluene. An interquartile range (IQR) is a measure of statistical dispersion and represents the range between the 25th and 75th percentiles of a dataset.

Benzene: A common industrial chemical found in gasoline, emissions from burning coal and oil, and tobacco smoke.
Toluene: Used as a solvent in paints, coatings, adhesives, and cleaning agents, also found in gasoline and vehicle exhaust.
COPD: A progressive lung disease that makes it difficult to breathe.
Emergency Hospitalization: Admission to a hospital for immediate treatment of a sudden and severe COPD exacerbation.
Time Series Study: A research method that analyzes data points collected over a specific period to identify trends and patterns.

The study revealed that increased levels of both benzene and toluene were associated with a higher risk of emergency COPD hospitalizations. Specifically, the ER% estimates for COPD hospitalizations after cumulative exposure of up to two days were 2.62% (95%CI: 0.17% to 5.13%) for benzene and 1.42% (0.16% to 2.69%) for toluene, per IQR increase. This suggests that even relatively small increases in these pollutants can trigger acute respiratory problems for vulnerable individuals.

Protecting Yourself from Air Pollution's Impact on COPD

The Hong Kong study adds to the growing body of evidence linking air pollution to respiratory problems, particularly for individuals with pre-existing conditions like COPD. While further research is needed to fully understand the long-term effects of benzene and toluene, taking proactive steps to minimize exposure is crucial.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.scitotenv.2018.12.015, Alternate LINK

Title: Effects Of Ambient Benzene And Toluene On Emergency Copd Hospitalizations: A Time Series Study In Hong Kong

Subject: Pollution

Journal: Science of The Total Environment

Publisher: Elsevier BV

Authors: Jinjun Ran, Shengzhi Sun, Aimin Yang, Lin Yang, Lefei Han, Tonya G. Mason, King-Pan Chan, Jinhui Li, Linwei Tian

Published: 2019-03-01

Everything You Need To Know

What did the Hong Kong study find regarding the relationship between benzene, toluene, and COPD emergency hospitalizations?

The Hong Kong study revealed that higher levels of both benzene and toluene correlate with an increased risk of emergency COPD hospitalizations. The percentage excess risk (ER%) estimates for COPD hospitalizations after cumulative exposure of up to two days were 2.62% for benzene and 1.42% for toluene, per IQR increase. This indicates that even small increases in these pollutants can trigger acute respiratory problems for vulnerable individuals with COPD.

Where do benzene and toluene typically come from, and how can I reduce my exposure to them?

Benzene is a common industrial chemical found in sources like gasoline, emissions from burning coal and oil, and tobacco smoke. Toluene is used as a solvent in products such as paints, coatings, adhesives, and cleaning agents, and it's also present in gasoline and vehicle exhaust. Reducing exposure to these sources can help minimize the risk of COPD flare-ups.

What is a time-series study, and how was it used in the context of research about COPD and air pollution?

A time-series study is a research method that analyzes data points collected over a specific period to identify trends and patterns. In the context of the Hong Kong study, this approach was used to analyze daily data on emergency COPD hospitalizations alongside air quality measurements of benzene and toluene. This method minimizes the influence of factors that don't change over time, such as smoking habits and socioeconomic status, allowing researchers to focus specifically on the impact of air pollution.

Did the Hong Kong study investigate the long-term effects of benzene and toluene exposure on COPD?

The Hong Kong study focused on short-term exposures of up to two days. While it demonstrated a clear link between benzene and toluene and emergency COPD hospitalizations, it did not fully explore the long-term health effects of these pollutants. Further research is needed to understand the cumulative impact of chronic exposure to benzene and toluene on COPD progression and overall respiratory health.

What does IQR mean, and how was it used in the Hong Kong study to assess the impact of air pollutants?

An interquartile range (IQR) is a measure of statistical dispersion, representing the range between the 25th and 75th percentiles of a dataset. In the Hong Kong study, the IQR was used to quantify the increase in ambient benzene and toluene levels. The study then estimated the percentage excess risk (ER%) of COPD hospitalizations per IQR increase in these pollutants, providing a standardized way to assess the impact of varying pollution levels on respiratory health.