New research shows that particulate matter deposits in the lungs more while walking, more in men than women. The least deposition of particulates occurs during the monsoon, followed by summer and winter.
Fine particulate matter (PM2.5) penetrates deeper into the lungs than PM10.
A five-year study conducted by researchers from Netaji Subhas University of Technology, along with a Noida-based consultancy, found that men have higher lung deposition of PM2.5 and PM10 than women.
This disparity stems from physiological differences, such as men's greater breathing volume and airflow. Respiratory deposition dose (RDD) analysis reveals that the maximum deposition of PM2.5 was observed in the Head airway region, followed by the Alveolar regions (deep inside the lungs), and the least deposition was found in the tracheobronchial region (neck areas and airways).
The study titled "Respiratory Deposition of Particulate Matter in Delhi: A Five-Year Assessment of Exposure Patterns and Health Risks" analysed data from 39 air quality monitoring stations across Delhi between 2019 and 2023.
The findings reveal a significant difference in lung deposition of air pollutants between men and women.
While sitting, men exhibited approximately 1.4 times higher PM2.5 lung deposition and approximately 1.34 times higher PM10 lung deposition than women.
When walking, men inhaled more pollution, resulting in lung deposition that was about 1.2 times higher than that of women for both PM2.5 and PM10.
Researchers attributed this difference to men's higher breathing volume and airflow, which allows more polluted air to enter their lungs.
Both PM10 and PM2.5 concentrations were lowest during the monsoon and highest in early November, coinciding with the onset of winter and widespread stubble burning in Punjab and Haryana.
Stubble burning, together with emissions from vehicles, industry, power plants, construction, and road dust, significantly contributes to the seasonal pollution peaks.
Their findings indicated that lung deposition of fine particulate matter among Delhi residents was approximately 10 times higher than expected under India’s air quality standards and nearly 40 times higher than levels estimated by the World Health Organisation (WHO).
The National Ambient Air Quality Standards set the daily PM2.5 limit at 60 micrograms per cubic meter and the PM10 limit at 100 micrograms per cubic meter.
On Diwali nights, particulate matter deposition in the lungs nearly doubled compared to pre-festival days, with elevated exposure continuing for several days afterward.
Area-wise analysis revealed that industrial areas recorded the highest lung deposition, followed by commercial zones.
In contrast, areas of central Delhi with higher green cover experienced lower exposure levels.
The study emphasised the urgent need for immediate policy changes to reduce everyday exposure, particularly for commuters and outdoor workers.