The impact of chlorine on atmospheric chemistry and air quality in the highly polluted Indo-Gangetic Plain

Delhi’s atmosphere contains the largest concentration of particulate chloride that has ever been observed. However, the ramifications of this for atmospheric chemistry and human health are only now beginning to be explored.

Under polluted conditions, chloride can be extracted from the particle phase and form gaseous nitryl chloride (ClNO2), which releases chlorine radicals on exposure to sunlight.

These chlorine radicals are highly reactive, leading to the formation of secondary organic aerosol and increased ozone concentrations. The aim of this project is to examine the consequences of chlorine chemistry across the Indo-Gangetic Plain.

I will use a combination of chamber-based experiments and fieldwork to understand chemical processes initiated by high atmospheric chlorine loadings, as well as to observe the extent of chlorine’s influence across the region.

The rapid development of field-portable mass spectrometers in recent years has vastly increased our capacity to observe precursor species that play a vital role in chlorine chemistry, in-situ and in real time.

I will use these state-of-the-art techniques, including chemical ionisation mass spectrometry (CIMS), in all experiments.

The outcome of this project will be an enhanced understanding of chlorine chemistry and capacity to model and predict chlorine impacts.

This can be used to inform policy in the Indo-Gangetic Plain, as well as being applicable to areas influenced by chlorine emissions across the globe.