As spring comes to the Northern Hemisphere, people all over are hauling out the yard furniture and shlepping barbeques out of basements. Everyone loves a cookout — but in Houston, Tex., the massive popularity of barbequing is contributing to the city’s notorious air pollution. Scientists at Rice University have found that tiny particles of polyunsaturated fatty acids from barbequing meat are “a somewhat important source” of organic particulate matter in the Houston-area atmosphere. The particles can lead to respiratory disease and heart troubles. Matthew Fraser, the lead author of the study, said he thought many other cities would have the same problem — although he acknowledged that “Houston does have a reputation for being the barbeque capital of Texas.”