Are China’s subways a shelter from pollution?

With a wall of wind and sand enveloping Beijing on Wednesday, many stranded commuters were left seeking refuge in shops and underground subway stations.  But is the air any safer in the subway?

According to a recent report examining the microclimate of Shanghai’s subway system,  only a small percentage of pollution makes its way underground.

Researchers from the State Environmental Protection Key Laboratory of Risk Assessment and Control on Chemical Process monitored temperature, humidity and PM 1, 2.5, 10 particles of the  subway tunnel in real time.

They found all particulates of air pollution were significantly lower than aboveground levels.

“Air quality in the tunnel was comparatively good, with 76% of PM2.5 and 91% of PM10  reaching relative standards,” the study said.

The average temperature when the data was collected in mid-November hovered at a comfortable 29.4 degrees celcius, while humidity was observed at 29.6%.

They also recorded a fluctuation in air pollution during peak and off-peak hours, something they partially attribute to the operation of more trains.

“This phenomenon might result from plenty of coarse particles generated by mechanical grinding in the process of train driving,” the study, Characterization of PM and Microclimate in a Shanghai Subway Tunnel, China, said.

As for the best day of the week to travel to avoid air pollution – Wednesdays apparently recorded the overall best environment.

Fridays, with a rush of people travelling throughout the city for the weekend, had the worse recorded particulate levels, followed by Thursday, Monday and Tuesday.

The study was published in Procedia Engineering and became available online on April 9.

Household mosquito repellant almost doubles chance of childhood leukemia in China

A study of childhood acute leukemia (AL)  patients in Shanghai has found household  mosquito repellants can potentially double the odds of contracting the cancer.

Tracking 248 newly diagnosed cases of acute leukemia  (AL)  and using 111 controls, researchers from the Department of Environmental Health at Shanghai’s Jiao Tong University assessed levels of  5 common household pesticides for the children.

From the data collected, they determined children exposed to household mosquito repellant had almost twice risk for AL, with a 1.9:1 odds ratio.

“The household use of mosquito repellent was significantly associated with an increased risk of childhood AL,” the study said.

Using  urine samples,  they tested for common pesticide ingredients  dimethyl phosphate (DMP), diethyl phosphate (DEP), dimethyl thiophosphate (DMTP), diethyl thiophosphate (DETP), and diethyl dithiophosphate (DEDTP).

Children suffering from AL showed higher urine concentrations for all 5 chemicals.

Measuring DMP,  known to be potentially harmful on the brain and nervous system, child AL patients were found with 13.2 micrograms per gram compared with just 3.6 for non-AL patients.

For DMTP, the results showed 31.3 micrograms/g for AL patients, versus 13.3 for non-patients.

“Childhood acute leukemia (AL) is the most common malignant tumor in children, but its etiology remains largely unknown,” the study,Household pesticide exposure and the risk of childhood acute leukemia in Shanghai, China, said.

“Our findings support the notion that the household use of pesticides may play a role in the etiology of childhood AL and provide some evidence to warrant further investigation of the link between household pesticide exposures and childhood AL in Shanghai.”

It was published in the Environmental Science and Pollution journal in April, 2015.