Main figures:

Fig. 1. Summary of fine particulate matter (PM2.5) chemical composition and source contributions. 
Figure 1b. The averaged relative mass contribution of different chemical constituents (here, EC is elemental carbon and OA is organic aerosols) to PM2.5 mass are shown for warm and cold period. Next, we represent the contribution of OA sources (CPOA- Cold season primary organic aerosol, BBOA- Biomass burning oragnic aerosol, UOOA- Urban oxygenated organic aerosol, COOA- cold oxygenated organic aerosol and HOA- Hydrocarbon-like organic aerosol) to OA. Further, contribution of different OA and elemental sources to oxidative potential (AAv, DTTv and DCFHv) are shown.
Figure 1c. The non-fossil fraction of diffferent OA sources, OA and EC in warm and cold period are shown.

Fig. 2. Spatial and temporal variation in fine particulate matter (PM2.5) and its species.
The right hand panel shows site-wise PM2.5, Nitrate, Sulfate, Ammonium, Chloride, trace elements and EC mass anomalies (averaged +/- 1 standard deviation) over the period of Jan- May, 2018.
The right hand side panel shows site-wise 10th, 25th, 75th and 95th percentile and median values of same parameters (as in right panel).

Fig. 3. Spatial and temporal variation in organic aerosol (OA) sources and oxidative potential (OP).
The right hand panel shows site-wise source-specific OAs (COOA, UOOA, CPOA, BBOA and HOA) mass and OP (AAv, DTTv and DCFHv) anomalies (averaged +/- 1 standard deviation) over the period of Jan- May, 2018. The right hand side panel shows site-wise 10th, 25th, 75th and 95th percentile and median values of same parameters (as in right panel).

Fig. 4. Near-molecular level organic aerosol (OA) source composition.
Figure 4a,b,d,g. It represents the carbon numer plot for BBOA, showing the relative intensity of dominant species containing CHNO and CHO in the specified OA source. These intensities are plotted against the number of carbon atoms (Nc) for different H:C ratios.
Figure 4 c,e,h. It represents the mass defect plot for CHNO containing species for different OA sources (CPOA, COOA and UOOA). The colors of the marker represent the number of carbon atoms and marker size represents relative signal intensity.
Figure 4 f,i. It represents the mass defect plot for CHO containing species for different OA sources (COOA and UOOA). The colors of the marker represent the number of carbon atoms and marker size represents relative signal intensity.

Fig. 5. Fig. 5: Drivers of fine particulate matter (PM2.5) and its oxidative potential (OPv).
Figure 5a. Spatially averaged relative contribution of different species such as inorganics, source specific OAs and elements to PM2.5 mass concentration and oxidative potential (OPv, DTTv and DCFHv).
Figure 5b,c,d. The comparison of PM2.5 mass and OPv in five different regions of the world (India, China, Spain, France and Switzerland).

The "India_Delhi2018_Rawdata.xlsx" contains the following:

• PM2.5 chemical composition sheet contains PM2.5 mass concentration, WSOC, OC, EC, inorganics (SO4, NO3, Cl - anions, Na, K - cations), inorganic carbon, TC_f (TC fossil), TC)_nf (TC non-fossil), EC_f (EC fossil), EC_nf (EC non-fossil), Oxidative potential (mass normalized: nmolDTT.min-1.µg-1,nmolAA.min-1.µg-1,DCFH nmol [H202] equiv per µg; Volume normalized: nmolDTT.min-1.m-3,nmolAA.min-1.m-3, nmol [H202] equiv.m-3 air), targeted Organic marker compounds measured by LC-MS and GC-MS, elements measured by ICP-MS along with sampling site details and date of sampling.
• The sources sheet contains mass concentration of OA and elemental sources (HOA,BBOA,CPOA,COOA,UOOA,Cu-Cd rich,Pd-Sn-Sb rich and K+ -Na+ rich).
• The AMS PMF input sheet contains signal intensity data and error matrix of all fitted ions (m/z) measured by LTof-AMS.
• The EESI PMF input sheet contains signal intensity data and error matrix of all fitted ions (m/z) measured by EESI-ToF-MS.

The cells containing "n/a" can be read as not applicable.