The recent study titled ‘Insights on the biological role of ultrafine particles of size PM<0.25: a prospective study from New Delhi’ has brought to light significant findings regarding the toxicity level of certain particulate matters (PM) in human lung cells. This article explores the research, methodology, and results of said study with respect to airborne particle toxicity and its effects on human health.
Methodology of Study
The data for the research was gathered six times monthly between January and December 2017 through a cascade impactor measurement device installed at IIT Delhi. This device measures fine particle size distribution. The team collected airborne particles in five sizes – 2.5, 1, 0.5, 0.25, and below 0.25 micrometers (µm) through filters.
Findings on Proportion of Ultrafine Particles and Mass Concentration
The research showed that particulate matter below 0.25 micrometers comprised the highest share in the composition of PM2.5 when compared to particles of other sizes. This extreme proportion of ultrafine particles revealed a risk of over two-fold higher cytotoxicity, as compared to exposure to other sizes, indicating high levels of toxicity to lung cells.
The post-monsoon season displayed the highest cumulative average mass concentration values for PM particles, followed by the winter season. High levels of PM2.5, recorded annually in Delhi during these seasons, have formerly triggered officials to declare health emergencies.
Reasons for High Levels of PM
These trends in PM concentrations are attributed to several factors such as Diwali celebrations, agricultural residue burning in neighboring states, and meteorological conditions fostering secondary particle formation. Conditions of low temperature and high humidity during winter nights tend to amplify the fog-smog-fog cycle resulting in PM concentration increases by 2-3-fold compared to pre-monsoon and South-West monsoon season.
Health Impacts Linked to PM
The harmful health effects of prolonged exposure to PM2.5 have been previously documented, including stroke, lung cancer, and other heart and lung-related issues. However, the impact of differing size fractions within PM2.5 has not been extensively studied yet.
The National Ambient Air Quality Standard (NAAQS), notified by CPCB in 2009, has set a PM2.5 threshold at 60 µg/m3 for 24 hours and 40 µg/m3 annually. Yet, it lacks specific policies for ultrafine particles. Pollutants covered under NAAQS include Sulphur Dioxide (SO2), Nitrogen Dioxide (NO2), Particulate Matter (PM 10, PM 2.5), Ozone (O3), Lead (Pb), Carbon Monoxide (CO), Ammonia (NH3), Benzene (C6H6), Benzo(a)Pyrene (BaP), Arsenic(As), Nickel (Ni).
Way Forward: Monitoring PM Levels
The findings highlight an important correlation between PM<0.25 levels and human health, creating novel insights for policy changes. Particular emphasis should be on routinely monitoring PM<0.25 and consequently establishing exposure limits for PM<0.25, considering the significant health risks associated with high PM2.5 levels.
Last Modified: February 9, 2024