HOUSTON—High levels of a cancer-causing chemical have been detected in air monitors in Houston neighborhoods near the busiest U.S. petrochemical port, according to a report issued on Thursday by city of Houston health officials and environmental groups. The report by the Houston Health Department and One Breath Partnership said they found concentrations of formaldehyde up to 13 times the U.S. Environmental Protection Agency’s minimum level for health threats. It recommended that permitting of plants and control of chemicals that contribute to formaldehyde formation be more tightly regulated. Formaldehyde levels appear to be increasing in Houston as the Texas Commission on Environmental Quality’s air monitoring sampling frequency is decreasing, the report said. Houston Mayor Sylvester Turner said the report is further proof of the impact of pollution on “high-poverty communities of color.” “The Texas Commission on Environmental Quality has the responsibility to take immediate action to strengthen existing rules to address …