Table 8.

In vitro attempts to evaluate incense-combustion toxicity

Study theme	Salient observations	Conclusions	Reference
Effect of temperature, relative humidity, and air-exchange rate on emission of 13 VOCs and semi-VOCs amidst incense burning where the release smokes have mainly gaseous phase including highly volatile organic compounds and polyaromatic hydrocarbons	Studies were performed in an environmental test chamber at 20°–130°C, relative humidity 5%–95% and 0.1–2/h air-exchange rate. Inner walls of test chamber were made using electro-polished stainless steel to minimise surface area and potential effects of organic-wall losses. No material of the chamber was plastic. Inlet flow-rate was 30 L•min−1. Incense was placed on a shelf in the centre and ignited using a lighter.	Analysis revealed increased emission with increasing ventilation. Air-exchange rate was the most sensitive parameter affecting formaldehyde, benzene (both carcinogenic), and diisobutyl phthalate (all PAHs) emissions. Temperature was the most sensitive factor for chrysene emission. Continued exposure resulted in benzene and benzo(a)pyrene emissions to close to or higher than air-quality standards.	[83]
Quantitative profiling of PM generated from incense smoke in Kanpur temples	PM10 mass concentrations as high as 2184 μg•m–3 was estimated within temple premises, exceeding the CPCB-recommended threshold of 100 μg•m–3. PM10 for the temple with highest attendance was 2336 μg•m–3. Average PM2.5 in the estimated PM10 load was 75%–92%. Data from normal days, so risk could be higher. Majority in accumulation state, particularly in winters.	Incense combustion–generated PM2.5 is a significant contributor to air pollution, with unpredictable and increased risks aggravated by seasonal variations and poor ventilation.	[11]
Shape-, texture-, and packaging-based VOC-emission patterns of liquid, mat, and disc configurations of three incense brands	Analysis using GC-MS showed 7.760±4.724, 3.122±0.866, and 1.192±4.724 mg/m3 smoke release for disc, liquid, and mat configurations. 14 VOCs assessed in incense smoke. Most were alkanes, followed by aromatic hydrocarbons and esters. Other major constituents were TSPs, PM10, PM5, PM2.5, allethrin, phenol, benzene, toluene, and xylene, along with multiple aromatic and aliphatic hydrocarbons.	Surface area (disc configuration had highest smoke release) is a key factor affecting homogeneous distribution and combustion of constituents in an incense stick. Most critical effects of incense burning were respiratory complications, inflammatory disorders, impaired nervous system functioning, and DNA damage. Carcinogenic health risk via BTEX (benzene, toluene, ethylbenzene, and xylene) exposure was highest.	[84]